texts: how to wire up LIS302DLH with arduino? (or similar, small accelerometer)

texts:
heads up: I'm new to electronics and have just started working with the arduino.

I'm trying to hook up a LIS302DLH accelerometer (spec sheet) with the arduino. I've successfully managed to get the adxl335 (e.g. link) to work but the adxl335 is too big for my application. That's why I was looking into the LIS302DLH. Unfortunately, I don't know how to hook it up.

Therefore my question: how to I hook up the LIS302DLH with the arduino? Do alternative small accelerometers exist that might do the job?

EDIT what want to know is how to connect (wire up) the LIS302DLH with the arduino. which pin needs to be connected to what?


texts:
I want to make a dimmer that would regulate the heating of an electric blanket using Arduino. I thought I'd use a Triac dimming circuit design for incandescent lights from the internet.

Are those the right type of dimmer to use with my electric blanket?

Here are some photos of the controller unit:


texts:
On a picture below, we have a scheme of an electronic (digital) circuit. What's the throughput of this circuit (Mbit/s)? What is the simplest way to increase throughput? Calculate this throughput.
8 means 8bit.

Finding throughput of this is pretty simple, 8/(11ns+8ns+4ns)=...

But what about the increasing throughput? How do I do that? And how would it be different, if the delays were in opposite order (i.e. 4->8->11)?

Edit:

What about parallel one?


texts: Does frequency equal the number of steps a stepper motor will do?

texts:
http://www.thorlabs.us/thorcat/ETN/ZFS13B-Manual.pdf

I am supplying a driving PWM signal to this stepper motor. However, I want to specify exactly how many steps to take with this motor.

Does the frequency of my signal = the number of microsteps it will take in one second (49,152 microsteps per revolution)? For example, if I have a 25 kHz signal, will the motor do 25,000 steps or approximately half a revolution in a second?

Also, I am unsure on how the amplitude (voltage) of my signal plays a role in stepping. Can anyone provide insight on this? Thanks a lot!


texts: Passive Voltage Divider attenuator design technique

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I want to build a passive attenuator which will attenuate an input signal. I want the to have 12 steps, starting with no attenuation and with each subsequent step having a 0.5dB attenuation (so down to -5.5dB). I will use a 12 way 2 pole rotary switch.

Because this is a passive attenuator the input voltage is unimportant, so for ease of calculation I will assume this will be 1V.

My work so far: I decided to have 13 resistors in a simple resistor divider configuration. I have worked out the percentage of Vin I wish to appear at each point. So 100% for the first point (direct connection, Vout = 1 V), 94.4% for the second point (Vout = 0.944 V), 89.13% for the third (Vout = 0.8913 V) and running down accordingly.

I was opting for 13 resistors to that the point under R12 will be 50% of Vin therefore R13 will equal the sum of R's 1-12

My question is: How I calculate the values of the resistors required because there are so many of them?

Do I just pick a value for Rtotal and work them all out from that, or can I formulate this mathematically and perhaps write some code to do this for me. Is there a way of exploiting the common resistor values to my advantage?


texts: Why does there seem to be a missing component in many PCBs?

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I've seen some PCBs were some components have been sketched, but they don't seem to be mounted on the board. See, this image (of a PlayStation 2) where the transformer has been drawn:

Why is this done on some circuits?


texts:
I, an inexperienced but curious and willing person, would like to have 4 LED spots managed together by 1 driver and a smart dimmer, but I would like to check if my plan is sound before turning $100+€ of LEDs in smoke because of a fundamental misunderstanding.
The spots I am interested in are 12V/3W (so 0.25A). They are sold with their own driver, but for aesthetical reasons I am thinking about using one driver only.
My understanding is that I should:

connect those spots in parallel after the driver (12V spots require parallel, not serie)
have a 20W, 12V DC, 1.67A driver (I understand that I need at least 12V, 4*3W and 4*0.25A, with some headroom). This driver could actually probably hold 6 of the spots I have in mind.
and a dimmer before the driver is the way to go (I am a bit confused about knowing if the dimmer should be before of after the driver. I understand that it is mostly before, know as primary). EDIT: I have been told by the seller that this dimmer is compatible. It is a 0-100W trailing edge dimmer, maybe it brings relevant information. But as I am looking for a smart dimmer it does not work for me.
EDIT: I understand from the comments that I need to keep the 4 small drivers to be safe. Fair enough, I'm glad I asked. Is it still OK to put the dimmer in front of this 4 drivers?

I am currently thinking about those spots (sorry, in Dutch, but basically small, dimmable, 12V, 3W), this driver and this dimmer (I specially like that one because it's thin, and fits in my design very nicely).
Questions:

is my plan sound? EDIT: no with 1 big driver. I slightly updated the question to take that in account.
is it stupid to replace the 4 drivers by 1 bigger? EDIT: yes
anything else I didn't notice due to my lack of skills/experience in this domain?


texts:
I have designed a buck converter and I am baffled with its comparator's functionality. The op-amp comparator does not give a PWM, instead it gives an amplified ramp.
What am I doing wrong?
Attached is my circuit schematic.


texts:
I am using ld1117v33 with Vin as 4.97v and trying to get Vout as 3.3v. I am actually getting this Vout without using any capacitors or resistors. The datasheet has suggested to use two capacitors, 0.1uf for input and 10uf for output along with a 120 ohm load resistor.

When I follow the circuit, I am getting Vout as 3.27v.

I can understand the usage of capacitors but not sure about the resistor used here. Could someone tell that if there is any advantage of using the resistor here? When I remove the resistor and leave the capacitors, it does go back to 3.3V.


texts: Low voltage disconnect with no quiescent current

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I'm a noob. Please correct my mistakes.

I'm making a circuit where I'd like to protect my Li-ion battery (3.7V, 3500mAh) from discharging too much. The batteries have a protection inbuilt which shuts of at 2.5V. I'd like to stop the discharging at 3V.

The battery connects to the PCB with a JST connector. The TPS78001 is a voltage regulator programmed to output 2.8V. I'd have a switch at the battery to turn the device on and off.

There's a lot of questions regarding this topic but I couldn't really come to any conclusions.

I feel like I have two options:

The EN pin is a shutdown pin for the regulator. I could drive it
    below 0.4V to shutdown the regulator or above 1.2V to enable it.
    Currently it is always on as it's connected directly to the battery.
    With a voltage divider certain setup (according to Dejvid this won't work)
    could achieve a shutdown of the regulator if the battery voltage
    drops below a certain level. This reduces the operating current to
    18 nA. But this still drains my batteries if the user forgets to turn off the switch.
Find a way to completely cut the power.

Should I go for option 1 because the 18nA draw is negligible (if the user forgets to turn of the device). Or should I go for options 2? If so how?

link full circuit


texts: Can someone explain how I turned on a circuit by touching it?

texts: I was just trying to learn how a transistor actually works by tinkering around myself. I have an Arduino running a flashing light program. I hooked up an NPN transistor to test out how I can make it into a switch by limiting the base pin with a potentiometer. So, I have the emitter hooked to ground, Collector hooked to the LED which goes to positive. Now I put a resistor in the base pin spot and when I touch the resistor, it turns on the circuit. From the little research I did, I learned that humans can emit a voltage? How true is this or am I just messing up a circuit somehow?


texts: Wien Bridge Oscillator - LT Super Low Distortion Variable Sine Wave Oscillator Debug

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I have been setting up a low distortion sine wave generator based on this design from LT (http://www.linear.com/solutions/1623):

For resistors R1 and R2 I am using a ganged pot so that both change together, however, I have found that when I change the resistance of my ganged pot the amplitude also changes which is not what I expected. Other simpler Wien bridge type circuits that I have seen use the same set up for changing the frequency so I'm a bit stumped as to why the amplitude changes in this circuit provided by LT. To make sure the ganged pot wasn't doing anything strange I replaced it with different values of fixed resistance and I still see the amplitude change with the frequency.

Can anyone offer some insight into why I'm seeing this behaviour?

Thanks


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I have a 4 layer PCB which has Analog ground, digital ground , AVDD as well as 2.8V and 1.8V. I think a 4 layer PCB is what I will use but I need to understand how to partition the power plane. For the ground plane I have it on Layer 2 and it is combined with AGND and DGND and I will minimize cross over on the top layer while routing.

But I am confused about the power plane. Does anyone have any suggestions? How do you handle multiple voltage levels on a power plane? Is there an alternative stackup?


texts:
I've recently become quite interested in building small breadboard computers. I've been reading a site that seems to be aimed for beginners, that builds a simple breadboard computer using the 6502 and some other chips.

When reading the above site I feel like I understand most of what's said, but I have problems with figuring out how to power my breadboard. It seems to be that I need to power the breadboard computer with a +5V DC power supply.

I've seen some single-board computers use USB as a power supply. As I understand it, USB outputs +5V. So I figured: I could probably try and mount an USB socket to my breadboard and use it as my power supply.

I don't have a background in electronical engineering (I'm in my final year on my CS degree, and I've only taken one very basic EE course), so I don't have any idea if doing what I suggest is a recipe for disaster, or a adequate solution.

So, is it possible to use a USB socket to power my breadboard? If so, how would I go about to connect it (schematics would be appreciated).

Thank you!


texts:
In control theory, an accurate transfer function of the components of your system, and some sort of guarantee that they are independent (low output impedance and high input impedances) are important for understanding your system, if you want to model it accurately.

Sometimes, this can be simplified -- when the frequencies of interest are far below the GBP of the components used for example, the component can be approximated as a component with a single pole and a large DC gain, both of which can be pulled pretty easily from the datasheet.

However, when you are trying to eek out all the performance you can out of a component -- ie using an op amp with a GBP of 3MHz and you want to use all 3MHz -- then an accurate transfer function might be helpful.

How do you find such a transfer function?  Can I just find all the points of the open loop Bode plot for an op amp and digitize it?  It is easier if I understand where the poles and zeros are, are there any tools to take something like this and turn it into a transfer function?  Is this done in "real life", or do people just work with approximations (or spice)?

As an aside, if this is something that is typically done, why don't manufacturers give the transfer function in the datasheet?


texts: Which is the correct voltage reference for a single supply instrumentation amplifier?

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I'm working on using the TI INA333 in a single 3v supply configuration.  I need to create a "mid supply" (half V+) for the REF pin.
I have thought of 3 ways to do this:

Voltage divider with resistors
1.5v Voltage regulator
1.5v Voltage reference

Here's the block diagram of the INA333:

It's going to be a battery powered device, so the solution that uses the least amount of current would be the best.


texts: Can I connect two power supply GND togheter?

texts:
Hi need to use a Raspberry PI in a project. I use a 5V power supply for it (by now a 2A phone charger), and it will controll a "power board" with some MOSFET, etc running at 12-24V. The power board is connected to an external 12-24V switching power supply.

Can/should I connect the two power supply GND togheter?


texts:
I've seen a video where the guy make a spot-welder using capacitors
https://www.youtube.com/watch?v=1SMUFSiaV-8
AFAIK shorting capacitor is harmful. The question is:
Are there any caps that can provide a high enough current needed for spot-welding still being within spec? Right now 70C 6A LiPo battery + arduino spot welder that shorts the battery for 0.2sec works well for me but I'm thinking about PSU + capacitors for the same purpose. Maybe supercapacitors?


texts: How to average output of current sensor to get smooth output?

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I am using INA138 current sensor with 100Hz, PWM duty 5%, 8-bit resolution signal load is a resistor,
I getting  zero readings while actual current readings also appear,
edited -
zero current sense output - this means when the current sensor detects OFF DUTY of duty cycle it gives zero volts on the output.,
the load is an LED,
controlling led brightness with a feedback loop,
I need to remove this zero by adding a low pass filter to the output of the current sensor
my sampling rate 255, cycles per second,
I need continuous measurement without going to zero, to make fast feedback control loop,
I get actual current reading 5-10 times per second while other readings are zero.
reading - 4.2,0,0,0,0,4.2,0,0,0,0,....
I have doubt,
What if I add an RC low pass filter on the output of current sensor?
I made small stimulation  100Hz 3.3V square applied to 50Hz low filter, (not 5% duty)

I see output voltage has averaged to 1.8V

how to avoid reducing voltage while low pass filtering?


texts: How to check if a high capacity, low voltage electrolytic capacitor is functional after long storage?

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I've found two 20 000 uF 50 V capacitors on a shelf, they've been sitting there for some 8 years. How can I find out if they're still good or not? I need them for a rectifier for my audio power amplifier. Additionally, I would like to check the capacitors that are currently installed in the amp to find out whether they all need replacement or if some are still OK. They have slightly varying capacities and voltages - 10000 to 20000 uF, 35 V to 63 V.

I don't have sophisticated lab equipment, all I've got is a DMM and a DC power supply with voltage source and current source modes (both V and I can be limited at the specified values).


texts:
I am doing a hobby project and I don't know much about engineering; therefore I decided to ask pros.

I have a 12v electric device that runs on Car battery only and I need to make it work if there is no power available. I need to get correct components that would make my plan work.

I need to:

add 8 x AA rechargeable batteries as a reserve power -- I bought this
add option to charge those batteries when there is 12V power available from the car battery [need help]
connect solar panel -- I bought this
add option to charge batteries when there is no power available, but solar panel is giving power [need help] I purchase this, not sure if it going to help
add option that prevents from draining the battery when car is not running [need help]

Problem: I do not have access to car ignition; and there is no way for me to do anything about it! Therefore only 2 wires are available: red and black. No access to harness or any other ignition-controlled wire.

How this solution should work:

When the can is on:

          `1. charge the 8x AA batteries`

          `2. continuously supply power to my electric device`

When the car is off:

          `1. cut the power from the car battery`

          `2. charge 8x AA batteries if power is available from the solar panel`

          `3. continuously supply power to my electric device`

When the car is not connected:

          `1. charge 8x AA batteries if power is available from the solar panel`

          `2. continuously supply power to my electric device`

Could you please advise which components I am missing and where to buy them to make my solution work?


texts: This is a solved  example from the book "Practical Electronics for Inventors" I did not understand how the voltages across the two capacitors  come to 9V when circuit is switched to A and then switched to B for the second time


texts:
I'm trying to build a 0 to 2A variable current source following the Linear app note.

Here's the schematic:

The circuit is a difference amplifier (LT1995) providing gain to the voltage developed across a sense resistor.  The amplifier output voltage is fed into a inverting integrator (LTI1880) with a RC network (R = 1k, C = 10 nF).  The output from the integrator is fed into a low pass RC filter (R = 100, C = 10 nF) and that voltage is placed on the gate of a P Power MOSFET (IRF9530).

The source of the IRF9530 is tied to the "low side" of the sense resistor (terminal going into the input P1 on the LTI1995 in figure).  The drain of the FET I have tied to ground for testing but I plan to have an inductive coil load in the future.

The output current in my measurements does not scale as \$\dfrac{V_{in}}{5 \times R_s}\$.  This is my goal for this circuit.

With no load attached (drain left floating), I provide voltage on the input (Vin) pin the amplifier output will develop a positive output as it should but the integrator will quickly integrate down to the negative rail (-15V).  The IRF9530 is operating with a very large (-15V) gate to source voltage in this case.

When the drain was tied to ground, and the voltage at the input was tied to ground the the FET gate voltage was -2.2V.

Can someone provide a better picture of the operation of the circuit and places where perhaps I'm assembling this wrong.  I have prototyped the circuit on the breadboard.

Datasheets
LTI1995:
http://cds.linear.com/docs/en/datasheet/1995fb.pdf


texts: Bidirectional DC motor driver from single analog pin

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I'd like to build about 12 units (too few to make custom PCBs, enough for time, cost and inexperience to be a concern) of a device mapping an analog (voltage, not PWM) input range of 0 to 5V to an output range of e.g. -12 to +12V, ~2W, with 0 output around 2.5V input. That probably has a name, but I have not found it.
Doesn't have to be exactly linear.

I can approximate such a device with a microcontroller (ATtiny85) and an H-bridge (L9110S), but with both input and output quantized at such a poor resolution (10 and 8 bit, typically), the result is too twitchy for what I'm driving (not motor, exactly, but a similar enough device using electromagnets).

Researching similar devices that are already being manufactured, I came across something almost perfect:digital audio amplifiers.
PAM8403-based boards are super cheap, assembled, efficient, have 2 H-bridges each, v.fast switching frequency, and drive stepper motors beautifully. And there are stronger amps available.
However, they achieve their functionality via AC coupling. So, a DC motor moves in response to voltage change, not absolute level. Without the input caps, they don't seem to work at all (at least, I couldn't make them)

What is the suggested solution? H-bridge-based motor driver + some magic on the 2 input pins? Modifying an amp's input? An analog circuit?


texts:
Which is the way to choose a resistor for a NPN transistor base?

I want to use P2N2222A as a switch, in a design as shown below. When I have voltage in base (1.8 V), I want a connection to be created between NODE1 and ground.

simulate this circuit – Schematic created using CircuitLab


texts: Lower maximum current rating on available motor driver .

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I am designing an arduino controlled autonomous bot with 2 DC motors to control.
The motors i have to use are 500rpm 12V Johnson DC motors with
Torque : 8kgcm and No-load current = 800 mA(Max), Load current = upto 9.5 A(Max) .

The motor driver i thought of using was the https://www.sparkfun.com/products/14451 TB66112FNG driver . The driver has nice standby and pwm control and really cheap too . While the application is going nowhere near 9A , still 4-6 A current can be drawn (as found while testing with multimeters on a single channel ) which can burn down my motor driver module .

I was hoping i could use a current limiter circuit to solve this problem . But i dont know how and if it will be possible to do so . Also please tell if there is any other way of solving this problem . I have already tried using power MOSFETS IRF540 , but it turned out to be a stupid idea as i had to use 8 mosfets to make a dual H-bridge all over again .

Any help would be of great value .


texts: This circuit is used in FXO.clarify what is the purpose of this circuit in fxo gateway.refer some link to know more about this circuit.


texts: How come rectifier diode current waveform is not distorted?

texts:
Shockley equation is non-linear but without any linearisation  effort such as in BJT small signal biasing, half wave rectifier passes almost an undistorted half sine wave.

In amplifier we bring the bias to a linear region for a small signal.

What confuses me in rectification theres no such thing as linearization  and we use the diode in non linear way but how come the current wave form is not distorted? Imagine a half wave or full wave rectifier with pure resistive load. The current looks not distorted. We have a non linear component yet the current is not effected from this nonlinearity it looks like. ?


texts:
For my work I have to install a linear screw motor from the company Igus.

It will be control with the constructor controller Dryve D1 (Dryve D1 Doc).

I understood how to connect the motor, the controller and the computer but they don't provide any power supply.

Have you ever used this king of motor?
Could you help me to find a power supply or a retailer?


texts: What do \$V_{TN}\$ and \$V_{T}\$ stand for in a MOSFET?

texts:
What is the meaning and difference between the symbols: \$V_{TN}\$ and \$V_T\$ commonly seen when talking about a MOSFET?

I'm guessing \$V_{TN}\$ is the threshold voltage, but what is \$V_T\$, and how do they relate to each other?

I'll give examples of equations where these symbols have been used in my course, and the context they were used in.

  e.g.1) When looking at the transfer function of MOSFETS, the NMOSFET is said to be in the saturation region if :
  $$V_{DS} \ge V_{GS}-V_{TN}$$

  e.g.2) When looking at the transistor as a switch, a PMOSFET is an open switch (off) if:
  $$|V_{GS}|>|V_{DD}-|V_{T}||$$
  Assuming source \$V_S=V_{DD}\$

What is the difference between \$V_{TN}\$ and \$V_T\$, and why is that last part an assumption? Is it not a given that \$V_S=V_{DD}\$?


texts:
I am interested in creating an LC oscillator circuit that uses a high voltage DC source. The DC supply is variable from 5-35kv. I have seen numerous posts about creating these circuits at low voltages, however none of them reference the use of a high voltage source. I am a little lost on what direction to look in (what parts to consider, what options exist, etc).

Sinusoidal high voltage and high frequency oscillations (Mhz range) within the tank are the goal with this project.

Thank you.


texts:
I found an example Verilog code as following:

module test #(parameter p=1) ();
    localparam [1:0] lp = ~(p)'(1'b0);
endmodule

I'm unable to undestand the localparam lp assignment.
Can you please explain the code?


texts:
I have read many website and forums about DIY reflow ovens for SMT soldering. I have also seen many solder profiles as specified by the solder manufacturers, component manufacturers, and other self-proclaimed experts.

I am having trouble understanding what is the best way to control the temperature. Unless I am mistaken, all of the recommended profiles that I have seen indicate the profile that the solder should undergo. But you cannot monitor the temperature of easily unless you have an infra-red camera which is difficult to obtain on a budget. All of the DIY projects that I have read about, including the nice pre-made controller from sparkfun, utilize a simple thermocouple to monitor the air temperature.

In my own reflow oven I soldered a thermocouple to a board and compared the board temp to a second thermocouple monitoring the air temperature. The two profiles were very different, as expected. The temperature of the board and the solder is going to vary based on many factors, including board size, which change the heat capacity of the board. Everyone is trying so hard to follow a specific profile as close as possible but if your feedback temperature is bogus then your controller is useless, right?

I have thought about putting a small piece of glass inside my reflow oven and attaching a thermocouple to the glass and using that to monitor the temperature because glass has a specific heat capacity very similar to that of FR4. But it would still not be perfect for every board of varying sizes. So what is the best approach to monitor the temperature?


texts: How to use SPI with DFRobot Beetle ESP32?

texts: Does anyone know if the Beetle ESP32 can communicate via SPI? I saw a project for a tutorial on SPI connection here, but it only mentions FireBeetle ESP32.


texts: Quiescent current on OFF/ON controller ICs seems high

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I want to improve an existing OFF/ON circuit in a project I have. Why do most off/on controller ICs have such a high quiescent current (approx 6 uA)? Their sole purpose is to manage an off/on battery circuit. The transistor I currently use has leakage of 100 nA.

I was looking at the MAX16054. I see they have a new lower power version (MAX16150) but it does not operate at the higher voltages. Other manufacturers seem to have the same limitations.


texts:
I am reading Arts of Electronics and they show these 2 circuits (p. 38):

Why \$V_{in}\$ has to be much larger than 0.6V?
How does the diode drop compensation work exactly? (I am looking for some really simple explanations, as I am new to electronics.)

Thanks.


texts: What is wrong with this PSpice simulation?

texts:
I am trying to simulate this circuit on PSpice as my first PSpice homework, I'm required to learn to simulate circuits on this software.

From calculations, we know that:

Ix = 16 A.
Current through 20 V source is 6 A.
Voltage across VCCS is 12 V.
Voltage across the CCVS is 8 V.
20 V source delivers 120 W.
10 A source delivers 200 W.
VCCS absorbs 192 W.
CCVS absorbs 128 W.

By going and simulating this in PSpice I got this, which is obviously a wrong simulation:
Error:
**** INCLUDING SCHEMATIC1.net ****
* source SDFGSDFGSDF
V_V1         N00310 0 20Vdc
I_I2         0 N00296 DC 10Adc
X_H1    N00596 N00608 N00608 0 SCHEMATIC1_H1
G_G1         N00296 N00596 N00296 N00310 0.8

.subckt SCHEMATIC1_H1 1 2 3 4
H_H1         3 4 VH_H1 0.5
VH_H1         1 2 0V
.ends SCHEMATIC1_H1

**** RESUMING kkkk.cir ****
.END

ERROR(ORPSIM-15142): Node N00296 is floating

What I double-checked:

Since there are multiple libraries providing the 0 symbol for the ground, I made sure SOURCE is the library providing ground.

For the the current controlled voltage source (CCVS), I made sure the PSPice library's symbol was G.

For the the volatage controlled voltage source (VCVS), I made sure the PSPice library's symbol was H.

Double checked all positive and negative signs.

Double checked all values

Simulation settings:

UPDATE:
It worked after changing the circuit to the following:


texts: An ideal op amp is given (with infinity gain), what is the current flowing through all the resistance for the given circuit?

texts: my problem is that do the output terminal of the op-amp behaves like short circuit of output terminal of the op-amp to its reference ground as shown in the ideal op-amp internal circuit?


texts: I need to use this GPS antenna on a model boat. As a result of placement, it will be submerged periodically (though I don't expect it to work while submerged), and damp often. What can I encase it in that won't degrade its performance while dry? I've considered simple two-part epoxy (the translucent kind), but worry about signal attenuation.


texts: R&S Spectrum Analyzer Voltage Measurement Error

texts:
I just got FPC1000 spectrum analyzer that goes from 5 kHz to 1 GHz. I didn't had any spectrum analyzer experiences before this one so everything is very new to me.

Among few things that I don't understand about it is also a significant error seen at SA when measuring a signal directly from function generator.

I applied 1,05Vpp/10kHz sine wave directly to input of SA (using BNC to crocodile connector cable since I don't have the real probe yet). 1,05Vpp approximately equals 4 dBm (power unit). But SA shows me exactly -2 dBm, which equals approximately 500 mVpp (which is approximately a factor of 2 smaller than the real value)!

Even if I set output function generator impedance to 50 Ohms, SA shows me 1.8 dBm, which is 760 mVpp.

Are the probes making an error? Or am I missing something here? I cannot find the solution for this case.


texts: Discovering operating power of a component without destroying it and without specification

texts:
I have a laser pointer component that I figured was a 9V pointer, and it worked nicely and shone very bright. I kept decreasing the voltage to see how low it could go, and it turns out it runs great on 3v!

I tried 12v also and it worked very well. How high can I go?


texts:
I have been doing some experiments on changing the medium contained inside a loop of wire from air to iron cores, and seeing the relationship between the potential difference established and the number of iron cores inserted inside the loop of wire. When I plotted the graph, the more iron cores I insert inside the loop of wire, the greater the voltage that was established in the circuit. Essentially I set it up like a transformer, and feed the primary coils with initial input voltage and see how the output voltage change in the secondary coils as I fill the transformer with iron cores instead of air.

My experiment Set up : I have no image but if I were to explain it, I have a long 30cm hollow rectangular cardboard, and coils wrapped around each end as primary and secondary coils. Then start the experiment by giving it initial input voltage, and slowly filling the hollow rectangular cardboard with iron cores.

But here is the problem, I expected some kind of linear relationship but when I graphed the voltage output (y a-xis), against the number of iron cores inserted (x - axis). However there seems to be a square root relationship. Now this is confusing to me because within my knowledge of physics and the mathematical equations, I cannot seem to explain this square root relationship.

Does anyone have an explanation for this square root relationship I am observing in my experiment?

(EDIT: Basically my question is why is there a square root relationship between the output voltage in secondary coils when graphed against the number of iron cores I used when I fill the transformer set up with iron cores instead of air (increase in magnetic permeability). Is there a mathematical relationship, or is it just my experimental error?)


texts: Using a fully differential amplifier as a differential ADC driver

texts:
Regarding my previous question, I decided to use a “fully differential amplifier” to obtain a voltage gain of 10. The source and ADC are also differential. The source is unipolar and its output resistance is given as 100 Ohm. I want to amplify the +/-200mV source voltage by gain of 10 or more. ADC input can be set to +/-5V or +/-10V. Below I have drawn the schematics:

Above ADC and the amplifier are just representative. ADC is actually a channel of a differential ended data acquisition board. OPA 1632 represents a fully differential amplifier but it is designed for audio. My freq of interest is not audio, it is actually DC to 150Hz and need low noise as possible.

If this topology is correct, before I start to build this I noticed I have some inexperience about some critical decision.

I summarized the questions for clarity:

I want to use 5 meters of STP cable between the source and ADC. Should the amplifier be right after the source or right before the ADC?
As far as I understand the voltage gain is 1+R3/R1 = 1+R4/R2 where R3=R4 and R1=R2. But what values of resistors are reasonable?
R1, R2, R3 and R4 will have tolerances. In that case how can matched resistor arrays be configured to obtain better CM noise immunity?

(Schematic does not show an anti-aliasing filter)


texts: Flyback transformer - ambiguous schematics and other issues

texts:
I'm currently using this schematic for a flyback transformer:

(source: eleccircuit.com)

As you can see, there's a big problem - neither the schematic, nor the website describing it, give the value of the capacitor. It says ".01", but gives no units.

http://www.eleccircuit.com/efficient-flyback-driver-circuit-by-ic-555-irf510/ Is the website. Anyone have any ideas what the unit could be? I used a 100pF capacitor in place (since I don't have a 10mF/nF/pF). I don't know if this could be a cause.

Since I don't have any 10K potentiometers, I used 2 10K resistors instead. Not sure if this could have affected it either.

I used a large steel screw (about 8mm diameter, 8cm long), wound bifilar, for the core. I do recall something about using something straight for it, maybe I'm wrong.

The only other possibilities I can think of could be poor assembly (bad soldering or unintentional shorts), defective components, or a bad schematic.

FYI, despite my tests, it hasn't worked at all (as in absolutely no arc, not just a small one, which to me suggests the type of core isn't the cause), although there is some current flowing in it since some components have heated up (but not melted).

Anyone know which of the above factors could be the problem?


texts:
simulate this circuit – Schematic created using CircuitLab

The control input may vary. What I want is, the relay will only switched on if the input voltage on R1 is at least 5 V. It works but the relay produce "buzzing sound" (like in the middle of switched OFF to  ON but not enough voltage).
Do I need more than this simple schematic ? Any suggestion would be appreciated, including op-amp voltage comparator example very welcome.


texts:
Please excuse my ignorance, but I am relatively new to electronics.  Sorry, also, for using the LED schematic.  I could not find one for a CFL lamp.

I am using a solid state relay (SSR40DA http://www.fotek.com.hk/solid/SSR-1.htm http://www.datasheetspdf.com/datasheet/download.php?id=789332) to control a CFL lamp.  I have measured voltages across 3 points in the circuit (AB, AC, and BC).  I did the measurements in various states (VDC applied/not applied, lamp on/off), and I got a surprising (to me) result.  When the lamp switch (D) is on and the relay is off, the voltage across it goes to 28V.  Can someone please explain why that would be?

Thank you very much in advance,

Fed


texts:
I have a question related to the Rds(on) property of a MOSFET (IRF630N).

Once the MOSFET is turned on (Vgs > Vth) will Rds(on) vary with the increase of Vgs? Or it is not affected by the gate voltage once the MOSFET is on. Will it be affected only by the junction temperature? How is Rds(on) related to the Drain current?


texts:
I designed a 50,000 volt power supply, that I am having problems with on grounding the HV side of the output. The HV appears to be injecting HV into my logic sections through the ground, damaging the drivers & square wave generator circuitry from time to time.
My requirements are a DC voltage that has a selectable output of +/-. Therefore, I have to ground the secondary side of my Fly-back transformer. My power supply's regulator and logic are all tied to a common ground.
I have been unable to locate any papers or info on how ground or isolate grounds for high voltage DC outputs relative to the logic or pre-driver analog sections of the circuitry.
Also, I should add that everything works very well without mishaps or otherwise, when the HV output is floating.
Schematic below:

My last thought was to isolate the grounds circled above. But if I do this, it may affect my 70V regulator's performance (I don't know).
Regulator section of schematics below:

Logic section of schematics below, ignore BJT:

To: Kyle B.
Yes, I have the HV ground return going back to the bridge rectifier’s GND. And it’s true all schematics does not show actual wire routing. I agree with the star method of returning grounds to their particular voltage source GND. I have used this in many designs on stepping motor drive circuitry in the past, and it works very well, even with active currents locking the motors on point.
But I have never worked much with voltages over 220 AC/DC. I don’t like using fly-back transformers (FBT) as high voltages source, but they will provide a semi-constant voltage to the load that I need. FBT are also a source of harmonic noise that has to be dealt with using chokes, snubbers, etc. I would rather use something like a Mark’s Generator, if it could keep a constant voltage to the load. Still working on all this.
Thank You Kyle B. for your thoughts, if you think of anything else, that would be welcomed.


texts: I am having some trouble to put things together into one picture. Can a modulated carrier wave be a square wave? If yes then How? Because at resonant frequency at the transmitter, the current oscillates between L and C. It takes time to charge and discharge and not abrupt. So how a square carrier wave is achieved? If No then can I ever generate a (say) FSK modulated square carrier wave? Also will there be any advantage/disadvantage (in terms of say transmission loss, energy per bit, suppression of higher order harmonics) of using a square wave over sine wave?


texts: Industrial electronics layout and design

texts: Why do industrial panels for oil and natural gas compressors or other industrial equipment use  terminal blocks for wire management? I have been doing some repairs for companies and was wondering why they chose that layout. I was thinking instead of all these wires going to different terminal blocks why not make a industrial PCB? Is this possible? Is it considered bad practice?


texts: Stepper Motors getting very hot after use

texts: I have a hobby CNC machine running with three cd drive stepper motors in it using a 2amp supply for all of them, it is run by Arduino uno and EasyDrivers. Suddenly I noticed them getting very hot, I am worried it might get damaged, please help I am new to this and cannot seem to find any answer. Also my old pc power supply got damaged which I was using to power the setup with I replaced with a 12 volt 2 amp power adapter, could this change be the reason for the overheat ?


texts: Determining width and length from CMOS inverter layout

texts: How do I determine the width and length from the following cmos inverter layout, given that lambda=0.25um? The answer is Wn=1.0um, Ln=0.25um, Wp=0.5um, and Lp=0.25um. I know that the length is equal to 2 x lambda, but I do not understand how to get width from the layout.


texts: Please help me solve the below Directional coupler problem

texts: I have tried and my answer keep coming 0db.I am not sure this answer is right as this is only kind of problem I have seen where port is short circuited.


texts:
I have an Atmega644p which is connected over SPI to a MCP2515 can-controller. In the MCU I use time based interrupts to send messages to the can-controller, which he translates and sends onto the canbus. I also use an external interrupt to tell the MCU when a message needs to be read out of the can-controller.

What I wish to do now is, generating with the same MCU a PWM signal.
My question is following, is there another way then time based interrupts to create one PWM output on the MCU? Aswell the other interrupts may not stop the PWM output.
Is this possible? or should I use some kind of PWM driver for this?

Kind regard,
Toon


texts: Which is the phototransistor in Lesson 11 Evil Genius?

texts:
My son and I are on lesson 11 on page 39 in Electronic Circuits for the Evil Genius second edition by Dave Cutcher. We have run into a problem in lesson 11. It uses an infrared LED LTE 4206/IR 3mm 940nM and an NPN phototransistor darkened glass LTE 4206E/IR 3 mm 940 nM in System 2.

The Green LED at i18-ground is supposed to be the output for System 2. The Red LED at d24-g24 is just letting you know that the clear glass IR LED b26-e24 is getting power.

What should happen? The IR LED (clear glass at b26-e24) is supplying light to the base of the NPN phototransistor (darkned glass at b10-d11), which should allow current to flow from collector to emitter and thus supply power to the Green LED output i18-ground.

What is happening: The Green LED output for System 2 is always on. It stays on when I block the beam from the clear glass LED. It stays on when I turn off the lights in the room.

The Red LED d24-g24 is acting as the output instead. When I place a barrier between clear glass and darkened glass the Red LED goes out and the Green LED stays on. When I remove the barrier, the Red LED comes back on.

The Red LED is not supposed to be the output. So the clear glass LED is bahaving as the phototransistor instead of the dark glass one.

Also, the Red LED is very faint when it's on. You can see this in the images below where I turned off the lights in the room. The clear glass LED is consuming over 7 volts so there's not enough voltage left to make a bright Red LED.

More details:

I have Q1 processor (NPN phototransistor with darkened glass) with the anode in b10 and the cathode (shorter lead and flat spot on lens) in d11. The IR LED (clear glass) for input with the anode in b26 and cathode (shorter lead and flat spot on lens) in e24.

I have also tried the other LTE 4206 and LTE 4206E that came with the kit with the same results.

Why is the Green LED remaining on and the Red LED is behaving as the output? The darkened glass phototransisto is supposed to be Q1 while the clear glass LED should supply IR light. It seems to be happening the other way around though.

[ED: jonk]: I have the 2nd edition. A fair use selection of Lesson 11 from the book follows:


texts:
I have been reading about the buck converter and have also referred to the various online resources like here.

In the above circuit, as I understand, when the switch closes, current starts to increase across the inductor linearly with time. What is the voltage at the output?

Current increasing would mean that the current across resistor would also increase linearly, and hence the voltage should practically be increasing, and not be stable, so how does it become stable/constant?

What exactly happens when the switch is opened?

The capacitor would cause ripples to pass through, but what about the resistor? From what I understood, the current decreases linearly with time and is due to the inductor (energy stored previously). But since it's decreasing, wouldn't the voltage at the output also decrease linearly with it?

So how do we get a stable output?

I guess the timing /duty cycle of switch would play a major part, but I still couldn't figure that out.


texts: 12v DC brushless PWM fan burnt out via Arduino Uno

texts:
I’m working on a project where I want to control the speed of a fan using a microprocessor.

I read several posts about using an Arduino Uno to control the PWM function on a 4 pin fan you find in PCs, and as I had the parts lying around I thought it would be a good place to start.

The fan is a Foxconn brushless 12V DC 0.6A – model number PVA080G12H-P01

My power supply is a 12V DC 1000mA probably from an old 3COM switch – model number 3c16741a

The supply has a barrel connector that fits the Uno so I thought this would work out perfectly.

I know the correct way to wire it would be to connect the fan’s power directly to the supply’s output and only have one control wire to the Uno, but as I was only at the ideas stage I didn’t want to hack into the cable just yet.  The Vin on the Uno can handle 1A, so I thought for an initial test I would be fine to use the GND and Vin on the Uno to power the fan.

Briefly turning the supply on made the fan turn very fast, as expected.  The Uno survived but there was a distinct electrical smell from the fan.  It’s likely the fan has never been used before, and almost certainly not at unlimited speed, so I thought it would be fine to move on and work on the PWM side.

I used the code by dlloyd here https://forum.arduino.cc/index.php?topic=415167.0 and connected the fan’s control pin to the Uno’s 3 pin.  Powering it over USB, it ran perfectly at three speeds for 5 seconds each, although at a low overall speed due to the limited voltage.  I modified the code to add 0% and 100% tests, unplugged the USB cable and plugged in the 12V supply.  The fan behaved erratically, spinning up, clicking, and slowing down randomly, before quickly going “pop” and stopped working all together.  Connecting it directly to the supply does nothing so it’s definitely dead.  The Uno continues to fun fine.

Due to the smell in my simple test, I’m assuming just connecting the fan to the supply would have resulted in the same death, but everything I’ve read suggests connecting a 0.6A 12V fan to a 1A 12V supply should be fine.  Can anyone explain how it could have happened so I don’t make the same mistake again?

Many thanks


texts:
Can you please help me find datasheet for this 2.2 ohm variable resistor. I want to know if it can tolerate 20 amps.
If you recognize the logo that would help a lot.


texts: Is the logic level of a MCU the same as the operating voltage?

texts: The Atmega328 has an operating voltage of 1.8V to 5.5V. If I was operating it at 3V (by supplying 3V to VCC) and set a pin to high, would that pin be at 3V?


texts:
I am trying to determine the shelf life of a typical Li-Polymer battery.  I have Googled but can't find any definitive view on the matter.

There are two questions regarding the battery shown:
1. What is the likely useful shelf life of an unused (from factory) battery
2. Referring to the image, clearly we have + and -, but what might the T terminal be for.  The voltage between +/T and also +/- is the same at 3.78v.

Many thanks


texts: Can I use a double insulated power supply with a metal framed sculpture with LEDs

texts:
I have built a tree shaped wire framed sculpture with LED lighting. The LEDs each have a positive supply to the anode via an insulated wire and resistor, and the cathodes are connected directly to the metal frame of the sculpture.

I have powered my sculpture basically using an old laptop power supply, DC+ connected to the supply leads and DC- connected directly to the exposed metal frame.

This is fine for me but I now want to make a few more similar sculptures to sell. I'm planning to find some suitable power bricks with 5V output and suitable current rating (no more than a couple of amps)

My question is: is this configuration safe in the event of a power supply fault, and can I sell a sculpture built with such an electrical configuration?

Thanks :)


texts:
In SSD1306 the segment current sets with resistor at IREF pin, and the current depends on VCC.

I have no stabile VCC, because it powered either directly from 9V alkaline battery or external 12V source, and I don't want create my own DC/DC or use internal charge pump (it too big consumption according the OLED's datasheet).

But I already has 3.3V stabile power source. So, can I use the following solution to create stabile IREF ~ 12.5μA (and therefore stabile brightness)?

And second question. Can I get any other trouble because of using not stabile VCC (but in the range from the SSD1306's datasheet)? VDD for logic is stabile 3.3V.


texts: Why does turning on/off one appliance make the other turn on/off on a power board?

texts:
I have a pedestal fan, and an elliptical machine (gym equipment) both connected to the same 4 outlet/port power board. I.e. a board you plug into a single wall socket and now have 4 sockets to plug things into.
The fan is next to my bed so I can adjust it during the night if I am too hot/cold.
I have noticed whenever I turn the fan on or off during the night, the elliptical machine starts itself up (the lights come on, the sound comes on, the magnets engage in the wheel). FYI the elliptical machine has a self off-timer, so its actually turning back on each time this phenomena occurs.
What could be the cause of this? Why does one appliances function somehow reset or trigger the other appliance on the same power board?


texts: help with microphone connection in TRRS audio jack

texts:
I have the following TRRS audio female socket meant for audio/stereo headset. As i understand the tip(2) is for left channel, the ring(3) is for right channel, the sleeve(1) is for ground.
Now which connection 10 or 11 is used for microphone?


texts:
First of all, just a caveat: I am a complete newbie with electronics, computer software is more my thing!

I have bought a (used) car this morning and it came with an old TrafficMaster Satnav installed which I have now removed. It seems that a power jack has been installed in the dashboard to power it.

I usually have my phone in a dock and run a long micro usb charging cable to a cigarette lighter USB charger so I can charge my phone while driving.

It would be nice to utilise the power jack that has been installed, to charge the phone as it will be a neater solution than running the long USB cable.

The old Trafficmaster is powered through a 2.5mm audio jack, the other end is moulded to the unit. Therefore the power jack installed in the car is the female end. This all works and the Trafficmaster recieves power.

The TrafficMaster is pictured here

What I want to do if possible is make a cable that has the 2.5mm jack at one end and a micro USB on the other.

Is it possible to take a spare USB charging cable cut the micro USB off, cut the 2.5mm off the trafficmaster and solder the ground USB wire to the ground audio jack wire and the 5V USB wire to the 5V wire in the 2.5mm connector? (Is there one!?)


texts: Again about four-terminal MOSFETs and relays

texts:
First of all, I'm a real noob at this, I was driven by a need I'll explain afterwards, but I'd like to start with the general question. This is exactly what was done in previous question (MOSFET with *actual pin* for body), but the answers don't really address my issue (or I cannot understand them).
I seem to understand that a MOSFET is actually a four-terminal device, where the potential between gate and bulk establishes the field that enables current to flow in the channel between source and drain, and it could be used like that (here my confirmation) but... it is (or rather has become) almost impossible to find a MOSFET that has been manufactured without linking two terminals (say gate and source) making four independent pins available (Why are discrete four-terminal MOSFETs so hard to find?)
My idea is that, if I could find such a MOSFET I could use it, without further  tricks, as a relay. I don't want source nor drain to be connected to the gnd, and I need to have no power consumption if I keep the relay on (MOSFET: When can we not assume that the gate current is 0?). Gate and bulk act like a charged capacitor with no further current flow.
How to use MOSFETs as relays has already been asked (How to replace a relay with a MOSFET? and How can I replace a relay with a MOSFET Transistor?), but again I couldn't find an answer satisfying my requirements.
So, to sum up my questions:

would my naive idea just work fine? In addition to the confirmation in the link above, further and more specific opinions would not harm!
is it really impossible to find a four-terminal MOSFET (independently from the answer to the first question: it would be anyway an interesting device)
is there a different way to realize what I need? I've looked for "MOSFET relays" and "solid-state-relays", but I seem to understand that they usually do absorb power for just being activated

Thank you!

Ok, I understand that even if I had my 4-terminal relay it woudn't be able to mimic completely the behavior of a mechanical relay with the benefit of close-to-zero absorption when only activated (dissipation while conducting was expected and not an issue). In particular it won't be like a simple switch being open or closed insensitive to applied voltages and thus able to let any kind of current pass. So let me add a couple of details of my purpose, because I still think that in my simple case they could do the trick in the easiest way.
A certain number of MOSFETs would be linked in series (source of the first going into the drain of the second, and so on). Each of them can or not be activated by the same voltage levels (say "vcc" and "gnd"), and they may be waiting relatively long times (thus the no-absorption requirement). Sometimes vcc will be applied at the beginning of the chain and gnd to the end, and if all the MOSFETs are activated current will flow. If I had the source of an intermediate MOSFET shorted to gnd, that would provide a path for the current to flow making all the subsequent MOSFETs useless.
I've read that 4-pin MOSFETs are becoming increasingly hard to find, but maybe it's not yet impossible! I'd like to know if the are still available in any case, but for this particular purpose they'd provide me an easy solution without the need to look for alternatives ("AND" gates?).


texts:
I have a DC switch rated at 2A at 36VDC, if I were running the switch at 4VDC what would be the maximum current I could safely run through it?

I'm assuming I can't simply use the wattage to calculate and I can't find a straight answer. Thanks for the help!

EDIT TO CLARIFY: It is a momentary spst on/off switch rated at 2a 36vdc being used on a high amp low voltage DC circuit.


texts:
Why is not doing any pulse shaping of a sequence of digital data  equivalent to a rectangular pulse shaping (as mentioned in some texts)?

I kind of see that no pulse shaping is rather equivalent to rectangular windowing of the whole sequence of data and that is not filtering (to my understanding at least)
Can someone help me understand this issue please?


texts: How does rewinding a smart card antenna into a smaller coil leave it operational?

texts:
Here is a description of how one guy extracted the electronics from a smart card and then embedded it into a ring wearable on a finger.

The card in question is more or less similar to the card in another question, the minor difference is that the card in the current question uses a thin (presumably copper) wire as antenna and the card in the linked to question uses wide thin flat traces. The wires run along the card perimeter. The card is credit card size, so the antenna is more or less an ellipsis.

So that guy uses solvent to soften the card plastic, strips the card and extracts the electronics. Then he rewinds the antenna wire so that the antenna coil can be embedded into the ring.

The resulting coil has several times smaller diameter yet the electronics work.

How does it happen that rewinding the antenna into a smaller loop does not break the card operation?


texts: What would it take to make a PS/2 keyboard interface hot-swap?

texts:
A long time ago, I had to service some of the early Compaq Desktop PCs. They used to have fuses on the motherboard that blew when a customer hot-plugged a keyboard.
I found this when googling on the topic:

The keyboard or mouse should not draw more than 275 mA from the host
and care must be taken to avoid transient surges.  Such surges can be
caused by "hot-plugging" a keyboard/mouse (ie, connect/disconnect the
device while the computer's power is on.)

Somehow, un-plugging or plugging in a keyboard can cause a surge.
I don't recall having these issues with serial ports (RS-232, Appletalk, etc), parallel ports, VGA, etc.
I've always wondered. Why is there a surge risk here?
What would have to change to make a PS/2 keyboard interface capable of hot-swap?


texts: Safe to turn off power by removing a plug fuse indefinitely?

texts:
I'm trying to turn off the power for my dining room light and as I live in an old apartment, my fuse box only has plug fuses (and a main fuse you pull out).  My plan is to cap the AC wires in the ceiling as I am going to use a 5v 2A adapter for an LED pendant I designed.  So my question is, is it safe for me to simply remove the plug fuse that powers the dining room and leave it out, with the socket exposed?
I have experience with wiring and working with micro controllers and LED strips, but not AC and fuse boxes.  In terms of safety equipment, I have rubber gloves (not thick though) and leather gloves, safety glasses and a voltage tester.  Please let me know if there is anything else I should know regarding proper equipment.
Thanks and I appreciate your help
panel


texts:
I'm brainstorming an electronics project where an Arduino (ATMega32U4 chip) will control this Noctua NF-A12X25 5V fan. I thinking of getting the 3-pin non-pwm version over the 4-pin pwm version and pwm the 5V signal to the motor instead. However, I'm not too sure whether to use a BJT or a Mosfest between the motor power line and the Arduino signal line. Below is a schematic of the two option I'm looking into:

Based on the specs of the fan, the motor will draw a max current of 0.35A so both the BJT and MOSFET should be able to handle it. But, I want the "transistor switch" to have as low of a voltage drop (i.e power consumption) as possible between the collector/drain and emitter/source when the motor is on. Thus, there should be more available power to the motor.
My electronics knowledge is still very limited and I looked at the datasheet for both the BJT and MOSFET. The BJT datasheet had a On-characteristic Vce(sat) of 0.2-0.3V while the MOSFET datasheet had different Vds values. This left me a bit confused.
If someone can explain which option is the better one and why, that'd be great.


texts: is it possible to make asynchronous down counter modulo 6 with 3 JK flip-flop?

texts:
in last week lab classes with my lecturer, we were asked to make an asynchoronous down counter mod 6 using jk flip-flop, but no one could make it until the end of the class. all of us has the same opinion, that the ff must be reset when the output is 111 (desired output: 101 100 011 010 001 000) by using NAND 3 input gate (input is QaQbQc where Qc is LSB) and output of NAND connected to CLR' of second ff. but our output is all the same, it stuck in 100 101 100 101 100 101 ...

so after i go home i tried again using proteus. and after analyzing, i understand that:
when switching from 100 tp 011 what happen is:

out comment
100 clk down Qc next=1,Qb next=hold,Qa next=hold
101 Qc' down Qb next=1,Qa next=hold
111 NAND gate is false, thus Qb reset
101 so the next state of 100 will never be 011

i think the third flip flop will never catch clock (Qb' from previous ff) since the previous ff is forced to reset before the third flip flop could "read" the inputed clock.

so is there really a way to make asynchronous down counter FF using 3 JK flip flop?

the circuit we designed:

https://i.stack.imgur.com/DrYjD.png


texts: Relation between attenuation and loss tangent in EM wave propagation

texts:
I was studying EM wave propagation in lossy dielectrics and came across two seemingly conflicting parameters of a medium. The loss tangent is defined as:

tanδ=σ/(ω*ϵ) ;

which clearly is inversely proportional to the frequency of the wave. So for a high frequency wave, the conducting medium would behave as an insulator to the propagation, and the power loss would be low.

Whereas the wave attenuation constant is defined as:

α= √(π* f* μ* σ);

which displays proportionality with the square root of the frequency. So at a high frequency, the wave would be greatly attenuated i.e. lose amplitude with propagation through the medium. But isn't this contradicting with the concept of low loss tangent thus low power loss? Am I missing something in the relation between attenuation and power loss?


texts:
I want to create small blocks (lego 2x2 bricks) that contain a small circuit that allows them to be recognized when stacked.

I have about 25 different colors. Of each color, I have 10 blocks. Each block contains a small circuit (slightly different per color) that has X connectors at the bottom (let's call that input) and X connectors at the top (let's call that output). Then I have a base plate that also has X 'output' connectors. When stacking those blocks in a small tower on the base plate, the input connectors of each block, connect with the output connectors of the block below it, of with the base plate. For the sake of the example, let's limit the tower height to 10 blocks.

What I want to do is connecting some device to the base plate (Arduino, for example) and in that device I want to be able to tell which colors of blocks are in the tower and how many of each color.

Is this even possible? And how?


texts: How come 2 MOSFET chips are needed in protection circuits?

texts: Like those here, the protection boards have at least 2 MOSFET chip (AO8814). Does anyone know why so many (4 fets) are needed?


texts:
I am trying to use OLED display in a dspic33f microchip. I've successfully initialized and sent data using I2C to OLED. I managed to display a small font(8pt) on the OLED. However, when I tried a bigger font, part of the font is being obstructed(can't show the whole part of that font).

The code is as the following.

static unsigned char buffer[1024 ] = {
    // @18 '2' (5 pixels wide)         //generated by using The Dot Factory
    0xC0, 0x80, // ##      #
    0xA0, 0x80, // # #     #
    0x90, 0x80, // #  #    #
    0x8D, 0x80, // #   ## ##
    0x87, 0x00, // #    ###

    // @9 '2' (4 pixels wide)
    0x00,
    0xC1, // ##     #
    0xA1, // # #    #
    0x91, // #  #   #
    0x8E, // #   ###
    0x00
};

void Oled_init(void){
    command(0xAE);  //display off
    command(0xD5);  //display clk div
    command(0x80);  //ratio -- continuation of clk_div
    command(0xA8);  //mux ratio
    command(0x3F);
    command(0xD3);  //display offset
    command(0x0);   //no offset- continuation of display_offset
    command(0x40 | 0x00);   //display starting line
    command(0x8D);  //charge pump
    command(0x14);  //internal vcc
    command(0x20);  //memory mode
    command(0x00);
    command(0xA1);  //remap columns
    command(0xC8);  //remap rows
    command(0xDA);  //com pins
    command(0x12);
    command(0x81);  //set contrast
    command(0xCF);
    command(0xDB);  //set Vcomh
    command(0x40);
    command(0xD9);  //pre charge
    command(0xF1);
    command(0xA4);  //entire display on
    command(0xA6);  //normal display
    command(0x2E);
    command(0xAF);  //display on
}

void display (void){
    command(0x21);  //column start address
    command(0);
    command(0x7F);

    command(0x22);  //set page address
    command(0x00);  //min
    command(0x07);  //max   //128x64resolution

    unsigned int i = 0;
    unsigned char x = 0;

    for(i = 0; i < 1023; i++){
      OpenI2C2(I2CConfig2, I2C2_BRG);
      IdleI2C2 ();
      StartI2C2 ();
      while(I2C2CONbits.SEN);
      MasterWriteI2C2(0x78);
      MasterWriteI2C2(0x40);      //Co = 0, D/C = 1, last 6 bit = 0

      for (x = 0; x < 16; x++){
         MasterWriteI2C2(buffer[i]);
         i++;
       }
         i--;

      StopI2C2 ();
      while(I2C2CONbits.PEN);
      CloseI2C2();
   }
}

This problem has been troubling me since the last few weeks and I still couldn't find any solution to it. Thanks for any solution in advance.


texts: Does the stability of a circuit depend on its feedback topology?

texts:
I am reading an article entitled "A Comparison of Two Approaches to Feedback Circuit Analysis" here.

If I understood the author correctly, we use return ratio instead of two-port loop gain analysis for stability analysis because return ratio doesn't depend on feedback topology.

As you can see in figure 4 and figure 5  from the article, there are two feedback topology with the same free-input source:

The first one is shunt-shunt feedback and the second one is series-shunt feedback.
The return ratio calculated for two cases are exactly the same and equal to 119.
However, the two port analysis results in different loop gains.

shunt-shunt feedback: loop gain = 28
series-shunt feedback: loop gain = 66

For that reason we use return ratio instead of two port analysis for
stability analysis.

My question is does the stability of a circuit not depend on its topology?

For example, the figure 4 and figure 5 are exactly the same if we set input sources to zero (Iin = 0 and Vin =0).

Should the two feeback toplogies have the same stability characteristic?

I mean if one is stable then the other also stable.

Thank you.


texts: Converting Short circuit solar cell (5v to 50mA)

texts:
How to convert solar cell short circuit current to Voltage. Because i need to display it to a 10bit micro controller. The voltage must within 0-5V.  I'm using a 3V 50mA (max output) solar cell.

Solar cell produce current when short circuit and produce voltage when open circuit.

i have tried so many methods but fail.

I tried transimpedance amplifier. but fail since it can only work for current that is in microAmp. i get negative value. for example 20mA gives me -2V. but if i go more than 25mA the value turns positive. Im tried using LTC1050, Tl081, LM741. i use 100ohm as rf. Inverting input. the non inverting is grounded and he solar cell + is to te -ve input and + to ground.

I tried using transistor but fail again. i used BC108, BC557, BC547, BC327, BC337, 2n5551.

I tried using hall sensor ACS712 which can sense up to 5A with sensitivity of 190mA. but fail because the Vo for 0 current is equal to Vs/2, which is 2.5V. the max value that i get didn't even reach 2.6 V. Which is too small.

I spend the last 2 months trying to think of a solution. So much time spend, energy and wacking my brains off but always meet a dead end with every method i tried.

Please, Please help me. I'm running out of time here. I have less than a day to figure this thing out or else i'm doom. Your help is really appreciated.

EDIT

Hi, sorry about the stupid comment. I'm new to proteus and circuit design. So as a newbie, i tend to ask weird question.

Anyway, i tried simulate your circuit from 0-55mA(my solar cell max current)  and it works.

But im wondering,

1) Will it works on Solar cell?
2) Will the result still the same using single supply?
   (a few voltage drop would be fine since its a simulation)
3) can i use voltage divider to reduce the V? cause i tried and the output is "nan".
4)I look up the data sheet of the ic and its a dual op amp. How do i connect it?

5) can you teach me how to do the calculation?
6) can you please provide a circuit with (0-55mA) range that does not exceed 5V because my Microcontroller can only take 5v. eg. 55mA-4.93 V.
And Thank you so much for your effort to help me. Really Appreciate it.


texts: Is there any accurate Temperature, Moisture or pressure reading strip?

texts:
I was wandering if there is any such sensor, that would read pressure, temperature or moisture ( approximately 12 inch long strip)? I want to be able to dip this sensor into water and have it be able to give me a reading of how much of the sensor is under water out of the total length of the sensor? So essentially I need a sensor that can take many readings along it's length telling me at each whether it is above water or below water by using any of the above methods.

If possible I would like for it to be able to adjust on the fly as well. I don't want to have to dry it off every time a depth changes.

Is this possible? Do you know of any place I could buy something like this?

Edit:
Thanks for the input guys. I found this : http://www.milonetech.com/Purchase_eTape.html
Do you think that will work with the accuracy I need? I think it would be easier to buy something like this than build it, but I may be wrong. Please tell me what you think. Thanks.


texts: Using RF for relative direction finding for short ranges (sub 10m)

texts:
I'm considering building a short-distance direction finder to determine the relative position of two objects.

I want to be able to determine direction through other objects, which eliminates IR or ultrasonic detectors. This leaves RF.

Antenna design I've seen seems focused on long distances and on quality of signal. However, my goals are short range (less than 10m) and direction. I don't care what gets transmitted, just where it comes from.

I expect that one of the objects would have an omnidirectional beacon and the other object a directional antenna. An angle slot of 15 degrees would be acceptable. I can deal with multiple antennae.

There's various antenna configurations that look like they'd be sufficient for directionality. They are: Yagi-Uno, dish and HB9CV-Beam. However, I don't see how to shrink them, or which ones are suitable for shrinking to short distances and small receiver sizes.

I expect I'll have to build custom mechanical and electronics hardware, although off-the-shelf parts would make my life a lot easier.

Here are some specific questions:

Which antenna configurations are suitable for shrinking?
I think I need a very small wavelength, so would be looking in the 2Ghz range.
Is that right?
What power output should I be considering? Is this at
all possible? Are there examples of this?

I have knowledge of electronics but am obviously new to antenna design. I appreciate any answers you might have.


texts: Need basic info about Programming microprocessor and its principle of operation

texts:
I have a a very basic question about how to design a microprocessor based system in contrast to a microcontroller based system. To have a better understanding of what i mean, i am presenting a general example.

Lets say I want to design an embedded system with 32 bit processor having ROM of 1MB and 1MB RAM @500MHz clock.

In micrcontrollers based system what i understand is, we simply burn our program into the internal ROM/Flash, when we power up, it starts with a reset PC(program counter)/IP(instruction pointer) which always indicates to the first RAM address from where the ALU unit begin fetching data from internal ROM/Flash and hence the execution of program starts.

In contrast to that, i assume we can not burn our program into the microprocessor chip as it doesnt have internal Flash for that purpose, so we burn the external ROM with our program, but than i dont understand how we tell the microprocessor to start the execution of the program written into the ROM etc.

As I mentioned my knowledge of digital world is not very limited, i have just used microcontrollers and that's it. I don't know the whole story inside microcontroller/microprocessor.

Can some one explain how the microprocessor starts its execution and how we program the discrete embedded system composed of microprocessor, external ROM and RAM ?

Please also provide some related material to study related to the topic.

I thank you all.
Regards,
Iftikhar


texts: Connect a microSD reader to a LilyPad USB, where are the digital ports?

texts:
I am attempting to connect a microSD breakout board to a LilyPad Arduino USB.
The microSD board has previously been connected to an Arduino Duemilanove.

In the Duemilanove setup, the following connections were made successfully:

(SD) -> Duemilanove

(CS) -> Pin 10 (SS)
(DI) -> Pin 11 (MOSI)
(DO) -> Pin 12 (MISO)
(CLK) -> Pin 13 (SCK)

Plus 5 V and ground.

I have attempted to replicate this with the LilyPad USB, following the schematic.

(SD) -> LilyPad USB

(CS) -> Pin D17 (SS)
(DI) -> Pin D16 (MOSI)
(DO) -> Pin D14 (MISO)
(CLK) -> Pin D15 (SCK)

However, the problem is, I cannot locate this digital pins physically on the LilyPad USB. I believe they are the six pins in a rectangle formation next to analogue port A2, but I do not know which are which. Following the forum post LilyPad USB v1.1 and SPI, I have tried that combination, but I have not had any results.

What is the order of the six pins? Also, where is the SS pin (that doesn't seem to be included there)?


texts: Significantly reducing speed of single-phase AC motor

texts:
I have a 1/3hp single-phase AC motor spinning my drill press.  With the maximum reductions available through pulleys it still runs 10x too fast for one of my applications (i.e., the chuck turns at 360rpm and I need it around 30rpm).

I'd be happy to cut the output torque proportionately to the speed reduction, but I've been reading about this for hours and I can't even determine:

For what types of small AC motors is sustainable speed reduction possible?
By what means?  Triac?  PWM?  VFD?
To what extent?  Is 10x speed reduction possible?

And then there's the problem that I can't even tell for sure what kind of AC motor I have.  I can see that it has a 16µF (run?) capacitor bolted to its side.  And here's a picture:

I'm further bewildered because typical hacks for this problem involve hundreds of dollars in gearing or special motors.  This entire drill press is $100, so I have a hard time believing there's not a sub-$100 solution.  E.g., I'd be happy to replace the motor with one that runs on household current at something like 200rpm instead of this one's native ~1800rpm.  But I haven't been able to find even that.

Am I missing some fundamental limitation to producing torque off of household AC at very low rotational speeds?


texts: Can off-line SMPS magnetics be used for wideband isolation of power line waveform measurements?

texts: As a corollary to this, can an off-line switching power supply's transformer, say the one from a switching wall-wart or laptop supply, be used as a substitute for the linear mains transformer in the linked question when making isolated waveform measurements?  Or would feeding it with a voltage that has low-frequency components in it damage the transformer somehow?  It seems like the bandwidth (tens to hundreds of kHz) and isolation (several kV) on such a unit would be more than adequate for the application...


texts: How to draw/include ESD susceptibility symbol on my designs?

texts:
I am using Allegro 16.6V.

I want to draw/include ESD susceptibility, non-recyclable and recyclable symbols on my design.

How can I do this?


texts: Calculate output impedance using negative feedback theory

texts:
This is a cascode amplifier. I would like to calculate output impedance of this circuit using negative feedback theory.

I have heard that there is a negative feedback here but I don't see where is the feedback so I can apply it to calculate output impedance.

Rout = rds1 (1 + loop gain) ≈ rds1*gm2*rds2.

Hope someone could help me out.

Thank you.


texts: Don't understand power relationship circuit analysis problem

texts:
I had this problem that I think involves Kirchoff's Current Law that I don't quite understand, unless this answer key is wrong.
My thought process is that P=IV, so why would R3 make a difference? If there's R3 there, the change in current and voltage would just be greater, but there wouldn't be a difference in negative and positive changes, would there?
So shouldn't S2 open be decrease? Since current through R1 would decrease, and the voltage wouldn't change, so power would decrease.
Am I missing something, or is the answer key wrong?


texts:
I design a DAQ to collect data from different sensors. The data are written on an SD card by a microcontroller, dsPIC33FJ256GP710A. The data are stored without a file system for speed reasons. Now I need to read the data acquired, store it on the SD card, with the PC. Are there programs for Windows that allow to convert the data on the SD card without the file system, sector by sector, in a txt or other type of file?

Thanks for the answers. I tried to use RawCopy64 because my OS is 64 bit, but this function allows me to copy files only between NTFS disks. This is not what I want.

Are there other parameters for this function that allow to read data from an SD card without a file system?


texts: What are these hardware components, and how do I control them?

texts:
My father received a video card in the mail last week. He gave it to me and I dismantled the card to get to just the video player and other components.

The labels here are based on my experience tinkering with it. I don't have any hardware experience to speak of. I plugged this into my Mac through the USB and found one folder, VIDEO, within which was the video played through the card. It was a .mov file. I tried replacing it with a random .mov file on my drive, but I got a Incompatible File Type message on the screen.

There are no other files or folders on the device (hidden or otherwise), beyond what Apple put in for Finder's indexing. It shows up as a FAT-32 drive.

I've been trying to figure out how to access the chip to change what filetypes it accepts or to put in some custom code, but how would I get into it? All I can see currently is the flash-drive section, not any executables to tamper with.

The three main black areas (I could use some proper terminology here) of the CPU (?) are:

"hynlx" 512A KOR (I guess Korea)
SAMSUNG 031 PCBO
ATJ2273B-C

Update: Here is the data sheet, but this doesn't get me any closer to accessing it.


texts: Phase Frequency Detector without dead zone

texts:
How does the two inverter delay stage in Figure 6.14 on page 265 of Design of CMOS RF Integrated Circuits and Systems helps to eliminate dead zone in Phase Frequency Detector ?

How does the PFD deadzone-free circuit ensures that the SR latches will NEVER enter metastable state ?


texts: What can I use instead of a CD4007 transistor?

texts:
What can I use instead of a CD4007 transistor, or how can I simply design a "20 watt or larger" speaker using a "TBA810" or any available widely available and used IC?
I found this circuit: Touch Volume Controlled Amplifier Circuit, And I can't seem to find that kind of a transistor.


texts: {enc28j60} Is the 50ppm crystal good enough

texts: I have some 25MHz 50ppm crystals but I am not sure if they are good enough to be used with ENC28J60.


texts: Monitoring distance between two moving objects

texts:
For a new product, I'd like some help in understanding what technology would be best for creating a wireless connection between two moving devices and having them constantly monitor the distance between the two.

I only need accuracy down to 1m or 1ft and then would love to know the max that it could go up to. Preferably, I'd like one of these devices to be a smartphone so if possible can this be done through wifi/bluetooth without any additional hardware? If not, what other technologies would be ideal for this type of measurement?

Assume the objects are both constantly moving in the same direction but only at about 2-6 mph.

Essentially I'm looking for one to be the master and for it to monitor how far the other object is away from it.

This question is along the right path: Options for short range distance determination between two objects


texts: So, I'm curious if there is a way to make a single-supply transimpedance amplifier op-amp circuit that uses a single supply. One thing that is important to me here is that it does not use a dc offset. This is because, if I were to ever use the circuit, it would be amplifying a steady dc signal! Just to clarify, I have no specific purpose for this at the moment. But I have certainly had one in the past!


texts: Tesla Car "maximum torque at 0 RPM" - is this correct?

texts:
Tesla Model S Wiki

I've been watching youtube videos on this car, and everyone states that the crazy accelleration is due to maximum torque at 0 rpm. Doing further research, this car uses an AC induction motor, not a DC motor.

From my old lecture slides, I remember that the torque curve of an induction motor is not this, but can be shifted (by varying the voltage/frequency, I can't remember).

Is the "maximum torque at 0 rpm" misinformation going around?


texts: Testing Amps And Resistance On PC Case Fan

texts:
Context: I'm wanting to tinker around with some mini solar panels to power some old PC case fans I have laying around. I know that case fans are generally 12v so I was thinking of running some 3v panels in series. I know some basics from college but I'm pretty much a noob. I decided some experimentation was order.

My fan connector has 3 pins, so I identified the center one as the 12V and one on the side as the ground (the other goes to the tach, which I don't care about in this case - the power supply connector doesn't connect to this pin anyway).

First I measured the resistance. I get a reading of 14.48 on the 20kOhm scale which should be 14,480 Ohms. That seems very high to me because that would mean the fan runs on 0.83mA which seems very low.

I had an old computer power supply laying around so I shorted the power on pin and hooked up the fan (so nothing else is hooked to the power supply besides the fan). I confirmed that the voltage is right around 12V and when I hooked up the multimeter in series I get a current reading of 0.18A which is much more inline with what I would expect, but that means I should've gotten a resistance reading of around 66 Ohms.

I know I'm missing something obvious here, but I'm not sure what it is. Any help? Thanks!


texts: Need assistance with current limiting resistor for LED

texts:
I am seeking some advise on a making an infrared light source.  I am using IR LED SE-5455-2.  I have found some calculators on line but the results vary.  I have also read many threads here.  I am still somewhat confused.

LED specs are Forward voltage drop = 1.7, reverse breakdown = 2, Peak wavelength = 930, forward continuous current = 100 mA.

I want to run 7 LEDs in series and power them with a 12VDC power supply that can deliver 1 amp.

How can I determine what I need for a current limiting resistor?


texts: ADC input circuitry and source impedance

texts:
I'm using a maxim ADC in my application from this family: http://datasheets.maxim-ic.com/en/ds/MAX1304-MAX1314.pdf

The devices have relatively low input impedance. If you look at Figure 5 in the above datasheet, on page 19, you can see the equivalent input circuit. My ADC is 0-5V range. My input signal however is in 0-10V range, so i have to reduce it to match the ADC.

If I use a resistive divider at the ADC input, it seems to me that I can not get a proper reading from the ADC due to the interaction between my 2 resistors, and R1 and R2 in figure 5. For example:

|                      Vdiv
|   Vin------Rdivider--------Rdivider---------> GND
|                       |
|                       |
|                       |
|                       R1 (3.33k)
|                       |
|                       |             Csample
|                       |-------/ ------| |-------
|                       |
|                       R2 (5K)
|                       |
|                       |
|                       |
|                       v
|                     0.9V

In the above figure, no matter what Rdivider values I chose, it seems to me that Vdiv will not be Vin/2.

Do I have to use an amplifier in the input for this case?


texts:
I have a processor which accepts MIPI data. However, the problem is I want to perform some processing on this data and the IMX6 is not fast enough to do this in real time. I was wondering what is the best way to have the FPGA operate on the raw pixels in my image.

One of the options was getting the MIPI data into the FPGA, decod the MIPI data using a custom core(which is rather hard), and then convert it back into MIPI and send it to the IMX6 processor.(https://www.nxp.com/products/processors-and-microcontrollers/applications-processors/i.mx-applications-processors/i.mx-6-processors:IMX6X_SERIES)

However, this means the FPGA has to be large to handle the MIPI logic. Is there any other way I can get the chip to communicate with my FPGA? Sharing a RAM(DDR) is rather complex and I dont want to go that way .

Is there anyway, I can have 2RAM and get the IMX6 to write image data into one RAM and then get the FPGA to read data from the RAM? If so how would I do something like this?

What is the way to get my FPGA access to image pixels without adding too much complexity?


texts: Are higher rated capacitors interchangeable with lower rated ones?

texts:
I have the follow capacitors that I need to change:

I can't find these specific ones on mouser or digikey and I can't buy in such huge quantities neither if they did have. I was told that I can use the following replacement for the Pink ones:
https://www.amazon.com/gp/product/B07RBC8F62/ref=ox_sc_act_title_1?smid=A1BBEKKND9EC89&psc=1
EKZE250ELL821MJ25S, Cap Aluminum Lytic 820uF 25V 20%(10 X 25mm) Radial 5mm 2150mA 4000h 105°C Bulk (50 Items)

But would I be able to use these same ones to replace the smaller blue ones too? These caps are both 16V, but the uF is different only, 470 vs 270. The replacement ones are 820uF and 25V much higher numbers.
I'd like to know why would these high rated ones work aswell?
What if I purchased or extracted caps from other boards that are greater than 470uF and 16V would those also work too?
Even though they do not look the same?


texts: Signal conditioning for 2SMPP-03 Pressure sensor

texts:
I am wanting to develop a circuit that accurately measures 15 Omron 2SMPP-03 sensors within its full range of -50KPA to 50KPA. Could someone give me a head start or refer me to some information on how to design an applicaiton circuit that conditions + measures 15 of these reliably at the same time?

I understand the sensors needs to be driven by a constant current source but there is not much information or any examples online or in the datasheet.

http://components.omron.eu/Product-details/2SMPP-03

Thanks


texts: How to filter hum from transformer for audio rectifier

texts:
i´ve just build a prototype speaker from a TDA7293 (http://www.ebay.de/itm/TDA7293-85W-100W-Mono-Audio-AMP-Amplifier-Board-AC12-50V-Update-vision-TDA7294-/201478109342), the circuit is quite straightforward. To avoid the noise of a switching power supply, i bought a toroidal transformer. While the music sounds astonishing good, in the quiet parts, or when there is no music, the system is humming in a quiet way but it is loud enough to be heard. I think, it is the 50hz.

So, how to filter the hum, since it originates from the toroidal transformer? But the transformer is giving AC, so i can´t filter it away. Does someone know, if this is a drawback of there cheap china rectifier? Should i buy a better one? And if yes, which one?

Or is there a possibility to filter the hum?

(I appended a photo of my prototype)

Ok, can´t attach a photo to a comment, (a little confusing because it seems, if i rather should edit my question than to add another answer), so i attach a new photo, i´ve already answered a question to stephen, maybe it is now all upside down...)

Hmm, it seems, if my comment were not added, so i type it here again. I´ve changed the setup but i can´t attach more than 1 photo (under 10 points), so i attached only the screenshot. I rearranged the setup, soldered most of the connection, but the hum is still there if i connect something to the input. I´ve feed some frequencies with a signal generator, and it is a little curious, the input signal seems to have more noise than the output. The hum is still there, but the music is rather good, if i can judge it on 30 year old blaupunkt car speaker chassis...


texts: Why is my guitar amplifier acting like a radio when I touch the volume knob?

texts:
I just bought an acoustic/electric mandolin (Ibanez M511SE-DVS) that I decided to test out with the only guitar amp that I have (a Baja BG-10). It works fine, but I noticed that when I have my finger on the volume knob, I receive (what is most likely) an FM signal to a local radio station.

Given that I don't have a background in electrical engineering, in layman's terms what are the reasons that a guitar amplifier would pick up a radio signal and feed it back through the output (speaker)? This behavior only happens when I touch the volume button.


texts: What are these two DIN-mounted components in my conveyor belt control panel?

texts:
I am inspecting inside my conveyor belt's control panel.
What are the components circled in blue? It reads "SF-10" on the transparent case, and appears to have a resistor (?) in it.


texts:
I have a boost converter that will convert 12V and 11A to around 20V and 6A. Since I didn't find any inductors (in my local stores) capable of such currents and frequencies and the correct inductance I decided to build one myself.

I've calculated the required inductances to be around 3uH for 11A and a couple of 710uH (for a low pass filters in 'boosted' section) for 6A, but am having doubts about saturation current.

I've seen an anwser on this site showing how to measure it, but I would like to calculate it prior to actually winding them.

I've seen some ferrite cores with 'air gapes' to achieve high saturation currents, I've seen toroidal and cylindrical cores with and without those air gaps. But I havent seen any specific numbers in their datasheets about the saturation current. So I am completely lost here...

So is saturation current dependent on core material/type/dimensions? If I know these values how can I calculate it?


texts: Capacitive distance sensor - humidity influence?

texts:
We are using a capacitive sensor to measure displacement (from here: https://www.micro-epsilon.com/displacement-position-sensors/capacitive-sensor/?sLang=en). However, we seem to notice a significant dependence on the humidity of the air on the result (temperature in the room is controlled and almost constant, humidity varies over the year from about 20%-50%).
The obvious cause would be a humidity dependence of the relative permittivity. However, I cannot seem to find any data of this dependence (except some for the static case). On the other hand, this surely has been measured.
So the question is: Is there data available for the humidity dependence of the relatve permittivity of air at frequencies from 20 Hz to e.g. 10 kHz?


texts: how to prove that TE modes cannot exist in microstrip structures

texts:
I kow that the modes in microstrip are TM modes.
I know that we have boundary conditions to see if the mode exists.
What boundary condtions i need to use for TE and TM?
Where do i put them in the equation bellow?
I know that for TM ,Hz=0
for TE Ez=0
How do i see that that is no TE mode in microstrip?
Thanks.


texts: Can I charge a 42V SLA battery pack using a 48V SLA charger?

texts:
I have a 36V 500 watt E-Bike and 3 12V SLA batteries. I just added in series a 6V battery bringing the voltage to 42V. Adding 12 volts more would fry the regulator but adding 6V from 36V was a handy hill climbing boost.

But now I need to charge a 42V battery pack but I cannot find a SLA charger at that exact voltage, however I can find a 48 volt SLA charger but I wonder, is too much difference in voltage?


texts:
I am trying to make an indicator that shows whether or not there is a load in the circuit, and if the mosfet is working properly.

I have come up with the following circuit, but I am not sure current will continue to flow through the LED if the MOSFET opens.

R9 may be an inductive load (with diode of course) with resistance about 100 Ohms and R10 should be lower.

I think when the MOSFET fully opens it will short-circuit the LED.

Will current still flow when the MOSFET is fully turned on?


texts: The logic schematic which can change the duty cycle of input

texts:
Is there a logic schematic can change the duty cycle of input ? I mean if input is a square wave with duty cycle is equal to 50%,and the output is also a square wave but its duty cycle become lower or higher.

I have found 555-timer,but it's too hard for me.so I still have no idea with it,i want to find a easier way to make it.can anyone give me some suggestion?


texts: Drive signal (duty cycle) calculation for PI compensator

texts:
I am trying to simulate an inverter with 4 ideal switching devices in LTSpice. I have the compensator working, however I don't the correct equation in terms of calculating the duty cycle.

What I have tried is this:

V=limit(abs((V(V_OUT))/391 + 1.1*V(Icomp)/391) ,0.01,0.99)

Which is essentially limiting the duty cycle from 0.01 to 0.99 and adds sinusoidal voltage output scaled down by 391 and the compensator signal.
Is there a problem in the way I generate the duty cycle signal, because it has distortion and reduction in amplitude of the output signal when inductive load is simulated.

NOTE: ADC range is from 0-686, 391 is just a fixed scaler.

I could provide more details, but I just want to find out the correct way of calculating the duty cycle. Nonetheless if more information is needed I will post it.

Simulation for PI controller is as follows:


texts: Which replacement Zener Diode should I use?

texts:
I am repairing a television power supply and have found a couple Zener Diodes that are bad. The service manual gives only a part number of VZMTZJ30DT. I have searched online for hours and cannot find any information on this component. Any help would be great.

I am working on a Panasonic power supply ETX2MM-806-AEL, and the component location is ZD501 and ZD503.


texts:
Does anybody know how to calculate this wave RMS value?
The answer is

I use Mathcad to prove it but I still can not get the answer.
Hope someone can give me help.


texts: Can I use a current transformer to measure voltage and current?

texts:
I am trying to make a very basic energy meter that is basically an Arduino (a random microcontroller) attached to a Current Transformer (CT) that I can clamp around an electric cable in an electric board (one for each phase).

For what I've understand I will have a function that, according to each CT specification, will translate me the current Arduino is measuring in one end of the CT, with the current the CT is measuring in the other end (the electric cable I want to measure).

I can estimate energy consumption over time if I assume that the voltage is constant (240VAC for eg.). However this is not always true and I want to be able to measure voltage as well, using this same CT.

How can I do that with a CT? Does the CT voltage outputted to Arduino vary in a way that I can correlate with the voltage on the measured cable?

The connection diagram is the following:

simulate this circuit – Schematic created using CircuitLab


texts:
I want to make multiple AND gate input device.
I have 4 locks (3 wires each; common, lock and unlock state) I want to monitor those states from locks and connect them to inputs (IC inputs) so when I have all 4 locks in the same state (all lock state or all unlock state).

This is what AND gate is for, to have one active output if all 4 conditions are same.
Basically I need two IC, (AND groups) one for LOCK, and another group for UNLOCK.
I want to make it as simple as possible.
If anybody can suggest how to connect it, drawing, power supply is 12V and I output needs to control small 12V relay.
What IC is the best for this?

Thanks in advance!

Table 1. Truth table for relay logic. OP to edit.

A  B  C  D  | RLY1  RLY2
------------+------------
0  0  0  0  |   1     0
0  0  0  1  |   0     0
0  0  1  0  |   0     0
0  0  1  1  |   0     0
...
1  1  1  0  |   0     0
1  1  1  1  |   0     1


texts: Relay contact sticking while driving a capacitive load

texts:
I am using a Panasonic relay (ALQ105) rated for a resistive load of 10 amps 5A at 250V to drive LED bulbs. These LEDs have capacitive circuits in their ballasts and hence draw high inrush current when switched ON. Steady state current is quite low (less than an amp at 220 Vac).

This inrush current (and possible spark during switching) is causing contact welding in the relay. I cut open one and found the contacts stuck together. A gentle prying with my finger nails separated them together. I couldn't find any black deposits (which I suspected would be there due to sparks). The value of capacitance in the circuit is unknown and different in different cases. As such I am looking for a general method to get rid of this issue. I could think of these three possible ways:

1) Use a series resistor and possibly an inductor to limit the high inrush current - Possible negative effects would be steady state power dissipation in resistor. Also, I am not sure about what values of R and L should I choose.

2) Use NTC thermistor like this - http://www.cantherm.com/media/productPDF/MF72_JUNE_2016_1.pdf

This looks a better idea as compared to L-R circuit but I am not fully sure of the calculations that I need to do for selecting the correct part.

3) Switching to solid state devices like triacs. Since there won't be any mechanical contacts, there won't be any welding. I am currently using BTB-16-800-BW triac in other applications. (ST BTB16 Triac datasheet)

This has a steady current carrying capacity of 16A which is much more than what my requirement is. It also has a surge current limit of 160 A. However I am not sure whether 160 A is good enough for the load I am dealing with.

Please help me selecting the best feasible solution for this issue.

[Updated relay contact rating to correct value of 5A at 250VAC]


texts: Do enclosed switching power supplies follow any standard for their chassis size and mounting hole distances?

texts:
Do enclosed switching power supplies follow any standard for their chassis size and mounting holes distances?
or each manufacturer has its own conventions?


texts:
I want to know how to measure this components in the attached picture. If I'm right they are beads. The second one the brown one I thought at first that it is a capacitor but I can't measure its capacitance so I think it is a bead too.

How to measure their values and what are they called?


texts: Interfacing PS/2 Keyboard to 3.3V inputs

texts: I have had wonderful success with my new Mojo FPGA, so I decided to try something more difficult, interfacing with a PS/2 keyboard, but I cannot get it to work. Of course, I took the proper precautions in going from 5V signals to 3.3V signals (I am not currently trying to drive the lines, just read off of them), but my simple approach, a voltage divider (safe, but not always appropriate) did not produce the intended result. I believe this is because the lines on the keyboard are open collector, having a low state and a high impedance state. I can think of ways to potentially solve this problem, but I'd like to get a second voice on the matter. My key design goal is simplicity, so solutions with discrete components like transistors are prefered over solutions with ICs, such as op-amps.