texts: Reasons behind placing power supply parallel capacitors in the correct order

texts:
I don't know if this was asked but I couldn't find a satisfactory answer in some related questions.

Imagine an IC or a sensor will be powered and some caps are needed to be installed in the vicinity. I know that the caps must be as close as possible to the chip/sensor.

But which way below is more proper for supply capacitor places? Dashed box is the sensor/IC.

Should the smaller or bigger capacitor be closer to the device supply pins?

I don't think the equivalent ESR will change by swapping them.

And most importantly how can the logic behind explained in an easy way?


texts: Making a Functional Computer out of an Arduino Uno

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Any Arduino enthusiasts out there?

Hey, I've been thinking about this and the more I think about it, the more I think I can actually do this. My idea is basically this: Make a functional computer out of an Arduino Uno microcontroller.

My only goal for this computer is the ability to edit and execute BASIC programs. That's all. I only want it for the programming, as that's just about the only thing I'm interested in right now :)

So the way I see it, I'll need three main hardware components:

some form of a display (VGA screen or something)
some way to register keyboard input, and
some way to store data to external memory.

Does anyone know of any way to do this? I know of ways to display to a screen, but I don't know a good API/hardware component to register keyboard input or to store external memory.

I'm going to need a lot of help on this. Can anyone help me out and offer ideas and useful tips and suggestions for good hardware / a good open source library, or two, or three, or ten?

Added:

Blog Making an Arduino Uno Computer for anyone who's interested.


texts:
I often see the block structure of NOR with source line for every pair of cells:

However, in this answer there is a design with source line for every cell. It confuses me because in this case I can see no resemblance with NOR gate at all.

Is it a different kind of FLASH NOR design or is it just wrong use of terminology?


texts:
I am designing a board with the ATmega328P and have decided to write my own bootloader rather than use Optiboot or Arduino, etc. I understand the logic of writing the boot code. Also that it resides in a specific area of the flash (max of about 1K). I am using the AVR Studio 6.

How do I target my code to precisely reside in that area? When I generate the hex file they always end up at 0x0000. How to locate them in 0x7000 or wherever the boot section is.


texts: How to use a Simpson 262 model 2 to measure voltage and milliamperage of solar cells

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In cleaning out my dad's garage after his death I found a Simpson 262 Model 2 meter.  As a hobby, I fix and upgrade garden and pathway solar powered LED lights. I have a box of miscellaneous solar cells --ranging in size from
In order to use them I need to know their voltage and milliamperage output.  To do that I would like to use that old Simpson meter of my dad's.  According to the manual, measuring the voltage should be straight forward --select the appropriate DC range, connect the positive and negative and read the meter.
However, the instructions for milliamperage says something about not simply connecting the lines but also something about needing a load in series and to never connect for current measurement without a load in series. What kind of load --resistor, led, or?
Also, I haven't actually used the meter yet as I have had to order a 22.5 volt battery for it.
In asking this question, I expect that readers will guess that I am not a technician of any sort --actually, I am a retired English teacher.


texts: 50W LED with 10W power equal to 10W LED at full power?

texts: If I buy a 50W LED and power it at 10W will it have the same brightness as a 10W LED at full power?


texts:
I have a design which will include the optional use case of boosting up to 7V from a li-ion battery.
I can't seem to find any drivers dedicated to li-ion for this? There seem to be a few buck boost that can generate 3V3. Should I use that 3V3 and boost using a standard boost converter? The Li-ion battery is also going straight into an IC which includes li-ion charge and protection circuitry.

I know this is wasteful use of the battery but will only be used if the user sets the jumper in that position as an additional (but limited) design feature.


texts: Water well water level sensor (indicator)

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I have a 400ft well, and I want to have a buzzer comes on every time water drops below certain level(280ft).
At the moment, I got it working using a 12V battery and a multi-meter. I dropped down an electrical wire(2 wires). Now the top ends are connected as follow: One to Battery Negative and the other to Multi-meter negative. Multi-meter positive is connected to Battery Positive.
This works fine, and the multi-meter reads 12V whenever the wire is submerged in the water. No reading when it's not.
Like I said at the beginning, I would like to have a buzzer, so I tried it using a transistor, a buzzer and couple resistors. Since water is not a good conductor, it did not work. The only way it worked is by adding a cork. The cork is hollow, and I inserted a metal plate, so water lifts or drops the cork for contact.
I also tried a five pin normally open/ normally closed relay. Same result, not enough amperage to trigger the relay. Had to use the cork again.
The cork won't fit thru the well. Testing was done outside the well.
Now the Pros of this method:
I feel like I could do it.
Cons:
Am I creating some electrolysis that eventually corrode the copper wires?
Anything other suggestions or different ways?
What about using arduino ? Could it act as a voltage sensor like a multi-meter then triggers a relay or something?
Any ideas will be appreciated.
Thank you


texts: Forward Voltage drop of laser line module

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I have a laser line module with the following specifications:

Operating Voltage: 2.6-5 V
Operating Current: <35mA
Output Power: <1mw

No where in the data sheet does it mention anything about a forward drop voltage (I am assuming this is a diode).
Is it safe to assume the forward voltage drop is 2.6V?

Product: Quarton Laser Module VLM-650-28 LPT Red Laser Line Generator


texts: Analytic calculation of active power error

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I have a component on a board which calculate the active power and reactive power.
The component first mesure the voltage, the intensity and the phase then calculate the powers with:

P = U * I * cos(phy)

Q = U * I * sin(phy)

I know the whole chain of voltage measurement (filter, transformer, ADC) has an accuracy of 0,6%.
I know the whole chain of intensity measurement (filter, transformer, ADC) has an accuracy of 0,9%.
I know the whole chain of phase measurement (filter, transformer, ADC) has an accuracy of 5,9°.

I need to do it for a general measure, I mean i can't use the partial derivative method because I don't have the value of U,I and phy.

Is there any way to calculate it?


texts: Confusion with power amplification concept in common base topology

texts:
A text is telling that a transistor can amplify power and gives common base amplifier as an example.
Here is what it mentions:

But what is the use of the transistor here?
Below I draw the same circuit with and without a transistor and plot the dissipated powers at resistors:

(left-click to see bigger view)

I dont understand, what is the difference?


texts: Output voltage of Class B Amplifier with global negative feedback

texts:
For the following schematic on the non-inverting input is applied a sine wave.

Shouldn't be the output on R19 0.9 out of the input voltage, by using a voltage divider between R31 and R19. From my simulation the input signal and output signal are exactly the same.

This amp is the final part of a simulation of an audio amplifier.
Any help is appreciated, thank you.


texts: How to wire ground when using an arduino with transistors and an external power supply?

texts:
I am currently working on an arduino project for school, however some of my LEDs dont turn on, and i don't know why. Right now i am using the first diagram, where i merged all - poles (ground), and only the LEDs "rood"and "green" turn on when all pins get powered.

Will this problem be fixed if i wire it up like it is wired in the second diagram? where will the current from the arduino digital pins go to then, since there is no way for that current to go back into the arduino, or is this not a problem and does the loop only have to be closed for the battery? (dont look at the difference in resistors, that was just a mistake on my part by not adding them in the seond diagram too.)

Thanks,
Jasper


texts:
I am building an ESP-based aeronautical battery capacity tester: a timed, current regulated, discharger. I got a partial schematic on the internet and, thanks to this forum, I learned [at least] one component was totally wrong. Now I am facing a second problem with the IRF540N. I am just testing separate components to verify they work as planned.
The current flow is [now] adjusted to 3.3A via an op-amp connected to the gate, in the final project, this controlling voltage is supplied through a DAC. This is my test configuration:

Test steps:
-5v independent power supply to the LM324N
-Adjustable power supply 0-30V 5A max to the battery connector, set to 5V.
-Adjust the POT to have a current of 3.3A
-Increase the voltage and verify the current remains 3.3A - OK!
-Works fine up to almost 12-13v, mosfet still cold.
-At almost 15V, the current jumps to 5A, limited by the PS
-the mosfet is cold but fried, shorted!
On the datasheet for IRF540N I read 33(23)A, 100V, 140W. I thought it is good enough to work at 28V 3.3A but it fried at ~15V in lesst than one second. Am I missing something? I have a huge heatsink with fan, I think I reached 66W or less and it fried! No time anyway to heat up.


texts:
This is an NMOS common source amplifier and I'm trying to calculate the Phase Margin, but it's starting from 180 instead of zero?
dose it mean I have poles at the origin or it's very stable?


texts:
I'm currently working on a project where I am pulling readings from 3 Gyroscopes (STM L3G4200D) to a Microcontroller (TI MSP430) and sending orientation data to the user.

I've been reading up on gyroscope data collection and it sounds as though gyroscope readings tend to "drift" over long periods. Would there be a good way of tracking or correcting for this drift?


texts: What OpAmp configuration is used in this circuit?

texts:
I'm studying basic opamp configurations and was trying to determine which configuration was used in this battery simulator. Its schematic is below.

The circuit description, from this application note, is below:

  In charge mode, current is forced through the battery input terminals. The low voltage that develops across R8 is amplified by U1 and causes Q1 to shunt the charge current while maintaining the power supply PS1 voltage.

Since the small current through R8 must come from right to left, the voltage on the non-inverting opamp input (+) must be higher than the voltage on the inverting input (-) for the opamp to turn Q1 on. That requires a positive output, leading me to conclude that the opamp is wired in the non-inverting config.

But the non-inverting (+) terminal is also connected to both the PS1 and the voltage regulator LT1073 ground terminals, leading me to believe that the opamp is in the inverting configuration, as in Figure 3 below.

So, in which configuration is this opamp really set up?

Figure 2: Non-inverting OpAmp configuration

Figure 3: Inverting OpAmp configuration


texts: How to model a practical zener diode in forward bias

texts:
In circuit (below) ,a practical zener diode (which is modeled as series zener diode and a resistor as given in question ) and other elements as shown in figure.
I am solving this circuit to calculate current  due to ac source at different conditions
I calculated current in two conditions
1.when zener diode act as   open circuit (in reverse bias)
2.when zener diode act as a ideal voltage source with resistance in series(in reverse bias)
But I'm confused in 3rd condition i.e when zener diode is in forward bias as we know in forward bias zener diode behave like a normal diode(considering ideal condition) and we can replace it by an ideal diode but
what about resistance of zener diode ? Should I remove it in forward bias conditions or not?


texts: Coming to electronics as a hobbyist I'm not sure I understand why I have to solder header pins?  On more than one occasion when dealing with Arduino / breadboard projects the circuit will not work until the header pins are soldered.  Holding them in place will not solve this problem.  Why?  Low voltage?  Need for persistent connection?  Holding them in place doesn't work nearly as well as it looks like it should?  Why?


texts: How exactly does one calculate the proper filter capacitors for the 567 tone detector?

texts:
I'm making a wireless remote control system using the 555 and 567 IC's.

Everything is working OK with the exception of the tone detector, yet I can hear the tone when I hook up a speaker to my circuit at the point where the tone detector can pick the same noise up.

I think it comes down to the input filter capacitor and output filter capacitor connected to the 567.

Currently I use 2.2uF and 4.7uF capacitors as filter capacitors, but there is nowhere online that dictates an equation for such capacitors and there's nothing that tells me what resistance to follow so I can even figure out a capacitor value.

The tone I'm trying to detect is a tone at 5Khz.

What equation do I use for the input and output filter capacitor for the 567 to successfully detect a 5Khz tone?


texts: Stepper motor troubleshooting with Pololu DRV8825 Driver

texts:
I salvaged a bipolar stepper motor (QH4-4242), and a power supply from an old printer that I'd like to tinker with before scaling up to larger motors.  With the limited knowledge about the stepper (such as current rating), but knowing that the power adapter has a 24V/.55A and 5V/.2A supply, I'd assume the stepper must have a rating equal to or less than .55A.  I've found coil wire pairs by measuring resistance (found to be ~8.5ohms).

Using a Pololu board built around the DRV8825, I've followed the instructions on their website connecting the correct pins A1,A2,B1,B2, to the corresponding coil pairs.  I've supplied the motor with the 24V/.55A output and tuned the current limiting trim pot while measuring the Amps in a single phase while the Step pin was high such that the current was .29A (since the phases only get 70% of the current at full stepping).  And I've set the sleep and reset to high as instructed.

Using a FEZ Panda II as the microcontroller, I wrote a simple code that turns high the step pin and sleep pin for 1 s, then low for 1 s.  The stepper motor makes a high pitch noise (as I've read is fairly normal for a chopper driver) and the shaft becomes difficult to turn, however it does not rotate.  While the pins are low, if I slightly move the shaft from the 'cogged' location, when the pins are back to high the shaft rotates slightly as if to snap back into place.  However it will not rotate nor step on its own.

I would very much appreciate any input or suggestions for debugging this issue.

Update:

Sorry for the confusion responders,  I thought one thing and wrote another last night.
My high and low for stepping is 1000ms or 1 second.

Pseudo code would look like:

while(true)
{
   step(true)
   sleep(1000)
   step(false)
   sleep(1000)
}

Update 2:

Per Richman's suggestion, I've added back to back LED's to monitor the switching of the polarity when a Step pulse is sent this appears to [pun] shed some light [/pun] on the problem.  And indeed found the issue.  The polarity was not switching when the Step signal was being sent.  This was because in addition to sending a pulse to the Step pin, I was also toggling the sleep pin which enables/disables the power to the motor.  I read this was done to minimize any high pitched noise, but I think I misunderstood and that enabling/disabling is done after ALL of the steps are carried out.  That's sorted out now.
Sorry to the responders for the confusion with the timing, I'd give you all the right answer since I explained it wrong if I could.

One unknown consequence is that the stepper steps on its own when the Step pin is left at low.  I am curious if this is because of noise in the signal which is perhaps causing the Step pin to toggle high/low even though my logic isn't telling it to?  Or perhaps there is a grounding/shielding issue because if I touch the motor casing, wiring, or even just put my hand near it, it begins to step faster and faster eventually becoming erratic.

Any thoughts on this new conundrum?


texts: What is ISCAS85 benchmark? I find it in a paper about BDD optimization, is there any simulator for it?


texts:
I have to do a project for my Uni, where one of the requirements is to connect DAC (AD5721 - Datasheet) with STM32F405RGT6 (Datasheet - package : LQFP64).

This is what I have so far (DAC connected with REF02) and now I have a problem how should I connect STM with DAC. The only thing I found is that STM has pins PA4 and PA5 that can be used as DAC_OUT and I'm stuck since then.

Next thing I'm supposed to do after this is to connect JTAG(IDC20) and RS232 to STM. I haven't tried anything with it yet since I need to solve previous problem first but if it's not a trouble I would also like to get some tips about this stuff too.


texts: Norator in series with inductor/capacitor

texts:
I know that if I have a norator in series with a resistor, I can replace the resistor with a short circuit.

My question is, if I can do the same with a linear inductor/capacitor?


texts:
Bit of a newbie to KiCad. Trying to get two edge cut circles, one with a diameter of 50mm and an inner one with a diameter of 40mm.

Here is my settings for the 50mm one (using 25mm as I assumed this was the radius measurement):

However this produces a circle with a diameter of 70mm. The same with the inner circle when I set the Point X and Point Y to 20mm, the resulting circle has a diameter of 56mm.

How can I get correctly dimensioned circle cuts in KiCad?


texts: Simulation problem for a multivibrator IC in Proteus

texts:
I have the following circuit in Proteus, and I try to simulate the functionality of the 74HC423 multivibrator IC:

The problem is whenever I change the values for Rx or Cx, the output's pulse width never changes..
Is it a problem with the simulator?


texts: Fastest way of transferring data from VHDL section to Microblaze processor

texts:
My basic application involves sending ADC samples to PC via Ethernet. The ADC sampling and storing is happening in VHDL section while the Ethernet socket programming code is in Microblaze processor.

Microblaze is running at 60MHz and the FPGA is at 100MHz (I've taken care of the CDC issue). For transferring 1k data it takes me 740us. I have a dual port BRAM where the samples are stored and upon an interrupt Microblaze will read it from the second port. For simplicity I have kept the BRAM read in always enabled state and I am reading the data based on address only.

Any ideas as to how I can transfer the data in a faster way.

I've added the BRAM connection details for more reference.
I've used the simple dual port type BRAM.

Buf_2k : Ethernet_test_data
  PORT MAP (
    clka => ADC_clock,                      --10MHz clock
    wea(0) => BRAM_wr_en,                   --Write enable generated synchronously to ADC_clock
    addra => buf_wr_addr(10 downto 0),      --BRAM address generated similarly as write enable
    dina => ADC_data_trig,                  --Registered ADC data to be stored in BRAM
    clkb => CLK_50M,                        --50MHz clock generated from DCM
    addrb => BRAM_addr(10 downto 0),        --Address coming from Microblaze to read the data
    doutb => BRAM_dout                      --This data out is directly connected to Microblaze
  );


texts: Converting arbitrary mic input number to dB SPL

texts:
I'm trying to convert an arbitrary input number from a laptop microphone into SPL. The microphone specs are available on https://docs-emea.rs-online.com/webdocs/105f/0900766b8105f0e3.pdf.

From what I've read on another article, the equation is 20 x log (V1 / V0), V1 being the voltage measured and V0 being the reference level. The reference level (V RMS) I've found online for -42db is 0.001776 but I'm unsure what the V1 number should be. According to the other article, it is the gain that the preamp has applied but I'm not sure if this relates to what I'm doing, or how to find this number.

Any help would be much appreciated.

The article I'm referencing is How to convert Volts in dB SPL.

Thanks in advance!


texts: Can I use pin as both an ICSP pin and as pwm output?

texts:
I have a microcontroller with 3 PWM pins, and I'd like to use those pins to drive the leds inside an analog RGB led.

Problem is that one of the pins is also the MOSI pin and I would like to re-program the microcontroller using ICSP.

What will happen if I try to program the microcontroller while I have an LED connected to MOSI? Does it make a difference if I'm driving the led from the cathode vs. the anode side?


texts: Unable to open XPS from PlanAhead(Xilinx ISE 14.3)

texts:
I am unable to open Xilinx Platform Studio(XPS) from PlanAhead. It shows me following error messages:

I have not opened multiple sessions of it. I have also removed the write protection for that folder. But still I get this error all the time!
Any solution? (Or should I open the .xmp file from the folder and then generate the netlist?)
Thank you.


texts: Sizing the pulldown resistors for 74HCT08 logic inputs

texts:
I have come across some text or blog before but I cannot find the source that: when we use 74HCT08 AND gate IC and for the logic inputs if we use pulldown resistors to prevent floating then we need to use the resistor pulldown resistor values Rp low such that the input should not rise over 0.9V.

Regarding a such input as hand drawn below:

Why does the value of resistor matter and how could high values make the input higher than 0.9V when the switch is open?


texts:
A core-type transformer, is constructed with \$0.014\$ in. thick laminations having a uniform width of \$2.75\$ in. If the maximum flux and flux density are respectively, \$6.2 x 10^8\$ maxwells and \$ 8.2 x 10^8\$ maxwells per square inch and the air space between laminations occupies 8 percent of the stacked core, Calculate the number of laminations in the transformer. Answer is 197

So I just started this chapter with transformer, first I tried unit analysis. So I multiplied \$ 8.2 x 10^8\$ maxwells per inches squared to \$2.75^2\$ and 0.08 divided it by \$6.2 x 10^8\$ maxwells and then finally divided it by the thickness. However, my answer is not even close to 197. But I think my solution kinda makes sense. Please show solution.

So \$\frac{8.2 x 10^8 Maxwells/inch^2(2.75)^2inch^{2}(0.8)}{6.2x 10^8Maxwells}\$ then divided by the thickness 0.014 inch. I got 57 only


texts: Plans / tutorial for sound effect generator using only analog components?

texts:
I've been wanting to make a laser gun sound effect attachment for my son's bike.  Currently, I'm using the electronics salvaged from his old laser gun toys.  All of them seem to use electronics hidden under a black blob of resin or epoxy, which I assume is an ASIC?

I'd love to be able to make this more cheaply, and was wondering if there's any resource out there to show how to make something like this with analog components.  I have an old fart machine that seems to use a combination of resistors, capacitors, and inductors to generate multiple sounds (i.e. no microcontroller), so I figure that it must be possible.

I only need one sound, but it would be great to be able to select from multiple, or somehow use a microcontroller + DAC to do it, although the latter would increase the price.

EDIT -- something like this, but cheaper than $10 would be nice
EDIT -- also found this schematic but it needs an IC called the HT2884


texts: Im not sure what im doing wrong the answer is 2V.


texts:
My goal is to produce a mouse with inbuilt macros. So my idea is mouse -> arduino usb hub (or raspberry pi) -> usb out -> computer. Where the arduino will process the input and will complete some aditional task based on the mouse input, then send it back to the computer. I don't want to rely on mouse to arduino then plug the arduino in. I want the arduino to produce the 4 pin signal to the computer.

Any suggestions as far as hardware is concerned for the best way to go about this!

Thanks alot guys.


texts: Scaling FFT output by number of points in FFT

texts: When computing the N-point FFT of some signal, the result is always divided by N. I can understand why this is the case for a summation over the N points, but often the result of the FFT operation is a vector of length N rather than a summation. Why then is the length-N vector that is the output of the FFT scaled by the number of points (N) used to compute the FFT? Thanks.


texts: In UART serial, do some devices not have an RX connection?

texts:
I am using this ultrasound sensor with a Pi. As far as I can tell, it only has a TX connection, and no RX, is this correct? I suspect it is the case, but still want a second opinion.

Also, the sensor TX pin 5 be connected to the Pi RX pin 10 correct? And any regular GPIO can be used on the sensor pin 4 to select real-time or filtered data?


texts: What is the standard 1-wire bus connector?

texts:
What is the normal connector that people put at the end of a long cable with a MAX31820 / DS18B20 temperature sensor at the other end?
What is the normal connector that people solder to the PCB when they intend such a cable to be plugged into that PCB?

I'm making a PCB that will go inside a small refrigerated box that (among other things) measures the temperature at various "interesting" locations inside that box and the ambient temperature outside the box, and drives a Peltier thermoelectric cooler (TEC) to keep that box at the desired setpoint temperature.

The MAX31820 / DS18B20 temperature sensor at each location are all wired in parallel in a 1-wire bus. There will be multiple sensors.
(It's actually 3 wires :-).

My Google searches turn up several pages that seem to say "there is now a
standard for connector pin-outs" for the 1-wire bus,
but each site's explanation of "the" standard seems to contradict the other sites.

Several different "standard" connectors and pinouts are listed in:
http://www.midondesign.com/Documents/1-WireApplicationGuide103.pdf
http://www.hw-group.com/products/poseidon/pos_interfaces_en.html
http://arduino-info.wikispaces.com/Brick-Temperature-DS18B20
-- each one shows at least 2 different connectors or pinouts on a connector.
Is one of these (or perhaps something else) the current de-facto standard?


texts:
I got one of these 5050 600 led light strips , according to the numbers it uses 12V at and 95 watts per 5 meters, that’s equal to 7.91 Amps, and they sent me a HUGE 10A power supply, everything seems nice and makes sense however I just measured the consumption of the whole 5 meters using a multimeter and it barely uses 2 amps, I'm just confused.
It just doesn’t make sense since the pcb does not have the normal 40mils per Amp rule to have 12 Amps running through the strip they would have to have at least 480mils, and those are HUGE tracks, measuring half of the width from the led strip I can confirm its 242mils which would limit the current to 6 amps but never 7.61.
There are some new 5630 led light strips those are supposed to pull up to 144W at 12V, being 12 Amps but those numbers don’t make sense anymore, someone please explain what’s going on here?
Short version :
The light strip is supposed to pull 7.9A and is only pulling 2A from the 10A power supply.


texts: interface circuit between amplifier and antenna

texts:
What type of interface circuit is used between the final amplifier output and the antenna? I see a lot of circuits use a group of inductors and capacitors after the amplifier output to the antenna. For example what are these capacitors and inductors after the coupling capacitor up to the antenna

1- Are these just filters?

2- I also want to know about impedance matching. Do I need impedance matching for my simple wire antenna, at frequency of 433 MHz?

3- How I determine the values of these capacitors and inductors ?


texts:
I'm self studying electronics, I am now familiarizing myself with the tl431, which is pretty much a "variable zener" aparently.
I was shown the following symbol.

I would like to simulate some circuits with it on falsad, I found this component, that looks pretty much alike and is called "SCR", after trying some circuits, I'm no longer sure it's the same component.

The question:
Is that a tl431?
If it is not, can I sumulate Tl431 in falstad?


texts: Transducer impedance decreased when Amplifier is connected

texts:
I am trying to measure beam pattern and impedance curve of a transducer from 70 to 120 khz. To get a nice plot, i have to use an amplifier(op-amp +-14Vs and Gain=14db) between a Signal Generator(Whose Max Amp. output is 4Vpp) and the transducer. The correct impedance of the transducer lies around 500 Ohm between 80 to 100kHz.
When i connect the amplifier(with Gain=14db) between Sig Gen. and transducer, the impedance decreases to around 100 ohm. The output Voltage coming out of amplifier is around 20Vpp. The question is why is there decrease in impedance.

Here is my sketch of the set up:- In first, the resistor is in front of the op amp THS3095 and in the next set up, the resistor is behind op amp. the resistor was used just to measure voltage drop. The impedance observed when resistor is before op amp is 50 ohm and when resistor is after op amp is 150 ohm.


texts:
I have constructed the following 12v in - 3.3v out buck converter circuit using a TL5001 PWM controller based on this document. After etching PCBs and soldering surface mount components the board unfortunately does not do what I expect it to. The output voltage is measured to be about 11.6v rather than 3.3v.

Measuring the output of the TL5001, i would expect a PWM signal however there is just a constant 12v (same as the input voltage). It appears that there is no switching happening in the circuit hence no change in the output voltage. I have double checked all component values and checked for shorts. Fairly certain that the circuit I have built is exactly the same as the one I designed. Have also replaced the MOSFET driver IC, TL5001 and the MOSFET itself to no avail.

This is the first time I have done any PCB layout. I don't think my board layout was very good - the filtering capacitors for the ICs are too spaced out for example. I'm not sure if this might be the problem?

Any ideas what might be wrong?


texts:
I am writing a library to use the CAN Bus on this STM32 board. Physically this board has CAN FD, which is CAN 2.0 compatible. I require a CAN transceiver to connect to the CAN-H and CAN-L lines.
I am trying to control a motor but the messages are inconsistent. Sometimes they are sent others they are not.
In the same CAN lines I have a USB-CAN to sniff the messages in the line, so I can see that the message sent by the controller is replied by the motor. I can see sometimes the message is sent by the controller but the motor is not replying. Sometimes the message is not read by the USB-CAN and I can see it should be because it is in the code. Other times no error occurs and it behaves at it should but it is unreliable.
Physically the STM32 board (CAN FD port) is connected to a CAN 2.0 transceiver and that transceiver to the CAN H and CAN L lines.
I can rule out that the transceiver is the problem because if I connect it to a teensy 3.6 and send the same messages, the motor replies as it should and runs all the time.
Do you think I need a CAN FD transceiver? Have you experience the same problems of unreliability ?


texts: Electronic Design Software for Large Electronics

texts: I have this gigantic box of electronics and was looking for something like Eagle (in the schematic sense) for large electronic constructs (something with components the size of an industrial power supply such as TIS 500-124-230). Any suggestions would be very much appreciated.


texts: SNR vs Signal Strength for digital throughput

texts:
I'm trying to compare two antennas, A and B for WiFi.

A is showing: Signal Strength of -77dBm, but SNR of 9dB.

B is showing: Signal Strength of -85dBm, but SNR of 24dB.

My understanding is as follows - but I'm no expert on the matter:
Better signal means I'll be able to receive data further away from the source, but better SNR means that signal will have a higher throughput (because less packets are being corrupted).

Does this make sense? And is there some equation to use both of these measures to form a single comparable number for digital throughput?


texts: Power over Ethernet identification error?

texts:
I have a custom board which is powered by Ethernet and I am using the LT4275B from Linear using the recommended schematic.

When I am using a cable with only the data pairs [1-2]&[3-6] ([4-5]&[7-8] are disconnected), I can plug as many of my boards I want and I have no problem.

But now, if I use a complete cable with the four pairs connected I have this problem :
If I plug a board I can see in the web page of the PoE switch the Class of my board and the consumption. Now I plug a second board (which is the same hardware) BUT I can't see my board, neither the Class nor the consumption. The switch consider the consumption of the second as if it was the one from the first board.

So for example I have two boards with 2W of power consumption, if a plug one board I have 2W on the first board. Then I plug the second board and I have 4W for the first one and 0W for the second one. And so on (6W for three, etc.).

I have this problem on all the PoE switch I had in my hand (Sisco, HP, and more).

Do you have any ideas ? Is it possible that the problem come from my RMII chip (DM9161A) ?

Thank you for your help !

EDIT :
When we cut the spar pairs it works properly as well when we use Ethernet Crossover cables... Strange...


texts: Can i replace an old transistor with a pn2222?

texts: Obviously this question is a little open ended, but I'm not sure where else to turn to fix my problem. Basically, a project I'm working on has a 5609 transistor and the emitter pin snapped. After some research I wasn't able to find a replacement on a website that I trust. I have a few pn2222 transistors and I was wondering if they might do the job. The pinout is the same and they're both npn transistors so my basic knowledge is telling me it could work, but basic is the keyword here. Does anyone have any insight on this? If more information is needed let me know!


texts: How does the formula for cross sectional area accurately determine which gauge wire should be used without including amperage or voltage?

texts:
p = resistivity

L = length

R = resistance

A = cross sectional area

A = p * (L/R)

What I don't understand is how it's physically possible to determine the appropriate gauge wire without knowing the volts OR amperage.

I learned this formula in a book for apprentices of electrical work and in the book this formula was used in a couple examples to solve for cross sectional area and from that determine which gauge wire is appropriate. This may be an odd question which I'm sure you guys get plenty of sense you're working in a field of magic but to clarify my conundrum: right now the only way I can make sense of this formula is to assume that the volts you are working with is an assumed variable.

Also I'm an apprentice for electrical work so I think a big source of my confusion comes from the fact that the which gauge wire I run in a home depends on amperage and amperage solely. What am I not getting?


texts: How to measure the signalling speed of Gigabit optical ethernet?

texts: Signalling speed of Gigabit Optical ethernet is  1.25 GigaBaud . I tried some methods such as measuring the UI of the eye diagram on a sampling oscilloscope by sending some random test patterns , high-frequency , low-frequency and compliant patters and also tried using an ethernet tester . But I'm not able to generate any stable eye patterns even though our scope is rated at 10GHz and recently calibrated . Any help would be appreciated .


texts: Combine left and right channel at speaker level

texts:
I recently started a project to build an inexpensive speaker/amplifier that is portable enough to take outside easily.  I purchased a center-channel speaker from a thrift store for $6 and an amplifier for $25.  I would like to combine the left and right channels so that both channels are represented in the output, but I've read conflicting information about whether this will damage the amp and/or speaker if I do it at the speaker level.

Right now I just have an RCA y-adapter to combine it at the line level (which works fine), but I was thinking it might work better to combine it at the speaker level so I can get more volume.  The amp pushes out 20 watts per channel, and the speaker can handle much more than 40 watts.

Is it safe to combine the inputs at the speaker level?  Can I do it without much additional expense?


texts: How can I design a simple dual battery e-bike protection circuit?

texts:
For context this is not my first ebike battery build.
I am in the process of building two additional battery packs for my new ebike.
I will be using 18650 cells with the appropriate 16s BMS for each new pack.
I will build two additional packs so that on long journeys I can connect them all in parallel using XT90 connectors.
See my simple schematic below:

simulate this circuit – Schematic created using CircuitLab
The schematic outlines my current problem.
In the "Sunny Day" scenario all three battery's are at the same voltage prior to connection. This means that there will be no issues connecting them in parallel.
In the "Rainy Day" scenario one of the battery's is not at the same voltage as the other two. If this were to happen, when connecting the battery's together the two packs at the higher voltage will try start charging the lower voltage pack, each pack will be able to provide a high current which may damage either the lower voltage pack BMS or the cabling or the cells. I will be using cables with an appropriate gauge for the intended charger, but not for charging via two battery's.
I am aware that this could all be partially mitigated by a couple of methods, such as:

Always having all 3 connected and charging all three at the same time
Having a voltage gauge on each battery

I don't want to use any of these methods as I want some flexibility (sometimes I might want to run with just one additional pack) but I also want a safety element build in.
Points to note before anyone suggests a way forward with this:

The ebike can draw up to 6000W, at 6KW and 67.2V that's ~90A. If the battery's are nearly flat 51.2V thats ~ 117A. Therefore any suggestions need to be able to cope with up to 117A!

A possible solution I have come up with (see schematic below) is to use a high current relay powered by a lower current relay (and power source) controlled by an Arduino Nano. How this would work, is that the Nano would be connected to the Vout of each battery pack and if the connected battery pack was outside of a tolerance (+/- 2V) then the high power relay wouldn't be triggered and the battery would remain isolated.
I keep thinking, there has got to be a simpler way, however I can't think of it.

simulate this circuit
I hope you now understand my problem, any help/suggestions will be very much appreciated.
Thanks.


texts: Why does a circuit need to be closed for a capacitor to develop voltage?

texts:
Apologies if this is a very basic question. I'm curious why in the open circuit below, the capacitor will not develop voltage. Shouldn't the positive terminal of the battery exert an attractive force on the electrons in the wire, causing a net positive charge to develop on the top plate of the capacitor? And then, because like charges repel, shouldn't the positive charges on the bottom plate get pushed away, thereby creating a voltage in the capacitor? Or will the positive charges not get pushed away because they have nowhere to go unless the circuit is closed?

simulate this circuit – Schematic created using CircuitLab


texts: What happens if you add a voltage source to the output of an op-amp?

texts:
I'm trying to self-learn EE and have a question:

What happens if you add an external voltage source to the output of an op-amp? Say as in this picture:

I know that WITHOUT the Va, Vout would just be Vin (is this a correct assumption? I'm assuming here that V+ = V- = Vin). However, we're adding a Va source, so would Vout just be Vin + Va?

EDIT: to answer mga's question, I made up the circuit but it comes from thinking about

The op-amp that I'm confused about is the bottom left one; the Vout of that op-amp is equal the voltage at the red A and I understand this mathematically but I don't understand it intuitively. Why wouldn't it be Vin + Va?


texts: What are the parts used in the pololu QTRX - RC sensors

texts:
I am making a line tracking device project, the number one important part of the device is the IR sensor itself. Now part of the project parameters is that it must be a single board and be only using smd components.

With my previous i had a really good time and success using pololu's QTR reflectance sensors and it already has a functional library that can be used in the arduino IDE (i went with SAMD21 uC). So as much as possible i would like to use this sensor and recreate it inn my board

The problem now is pololu does not say in its resource files what is the name of the sensors they using; so that i could search and buy them ( i would be needing 30 since i would be doing similar to the 31 high density ones.)

Thus the question:

Do you know what sensor is pololu using in their QTR reflectance sensors

On a related note. As a backup plan i seriously plan on considering on de-soldering those sensors off the board if i could not get them. but there is still one problem. The pololu QTR has an ic that i could not find a datasheet off This picture on the right. What is this 622k IC and what does it do so i might be able to find an alternative, i have noticed that there is 1 of this IC for every 4 sensor.

Also the QTR reflectance sensors comes in 3 versions, 2 of which are notable the QTR and the QTRX. Based on the description Both have the same type of sensors but the other one is "lensed". What do you think the purpose of each one? from reading the description alone i could only find that the current rating is the notable difference


texts:
I have been struggling with updating a netlist and design synchronization in OrCAD.
My co-worker created a schematic in Capture CIS and prepared an initial layout. Then, I took over the project and started doing further job.
In the meantime, I've added some elements and deleted the old ones.
I receive many errors like:
ERROR(SPCODD-409): Error at line 129 while loading the C:\USERS\AAAA\DOCUMENTS\PROJECTS\XYZ
2020-09-03-1200\allegro\pstxnet.dat file. Unable to create the following new pin instance, 2, as the pin definition was not found.
Reference Designator: J40.
Schematic Instance: @\XYZ.\XYZ(sch_1):\INS1109293@\CONNECTOR.\MC1.5/2-G-3.81.Normal(chips) (MODULE: XYZ; PART: MC1.5/2-G-3.81).
I'm not capable of generating a netlist because of the errors above. Even if I delete elements mentioned in error, I still receive errorsreferring to non-existing elements. In the netlist file, there are duplicated connections for designators that are not existing anymore.
How can I solve that problem once and for all?


texts: How to select the best diode for a full-wave diode rectifier which gives the most efficiency and minimal power loss

texts:
I want to make a bridge rectifier that can convert 230 VRMS 50Hz AC into fully rectified DC, but I don't know what particular diode to use for my circuit.
In particular, I want to use Schottky diodes due to their increased efficiency and minimal power loss but all the diode combinations I have tried so far haven't worked.
Here is my current diagram where I use the MBR40250G Schottky Diode since it is 250V.

update
here I have increased my capacitor value from 100u to 430u and this is my output

update 2*

here i have updated the sine voltage to 100Vrms
final update

![enter image description here


texts: What are the differences between triacs?

texts:
I need to replace a broken BT134-600E triac. I found out it's 600V 4A sensitive gate triac. Which of the following triacs can be used to replace the original one and why?

MAC97A6
MAC97A8
BTA16-600B
BT137-600
BT138-600
BTA208X-800E

All the triacs datasheets can be easily found on google.
The broken (exploded) triac is from a cheap soldering iron which has a really simple circuit.

Thanks :)

Front and rear of soldering iron PCB. Click or double-click for hi-resolution.


texts: Altium "Where Used" search in multiple projects

texts:
Our design repo has multiple projects (SVN controlled) and we use an on-site library of parts.

I'm looking for a way to search all of our projects for instances of a specific part. The intent is to identify projects that contain parts that have gone obsolete, then kick off tasks to add a suitable alternate for all projects.

I've seen reference to "where used" in Altium Vault, but can it be done without?


texts:
I have selected an infineon BFP840ESD BJT to work with in the design of a low noise RF amplifier. I'm trying to use Qucs Studio to simulate it.
From the datasheet I select my bias conditions with as low a possible value of Ic to give better noise performance. I select \$I_c=6mA\$ and \$V_{CE}=1.8V\$ with a corresponding base current of \$20\mu A\$:

I'd like to use this simple biasing setup using RF chokes and DC blocks:

I calculate \$R_b = \frac{V_{bb}-0.7}{I_b} = \frac{1.8-0.7}{20\mu A} = 55 000 \Omega\$
I set up the simulation as follows in QUCS studio:

I've selected the file to use in the s-parameter block as a .s2p provided by the manufacturer generated for the same bias conditions as above.
I'm expecting to read 6mA on the ammeter when I run the calculate DC bias function to verify the biasing however I am reading 0 as shown above. I'm completely new to using both QUCs and designing RF amplifiers so I am at a bit of a loss for what I'm doing wrong.
Could anyone help me understand how to correctly bias an RF transistor and set it up for simulation using s-parameters in QUCS?


texts: Logic Converter driving logic level Mosfet Gate

texts:
I am wondering if anyone can comment on the feasibility of this circuit. My ultimate goal is to switch a 12V solenoid on and off using a 3.3V microcontroller, but I have had trouble so far. I want to switch the solenoid on when the I/O pin goes high, and the solenoid to switch off when the I/O pin goes low. I am trying to find the simplest way to do this.
I bought a logic level mosfet with the original intention of driving the mosfet gate directly with the 3.3V I/O pin of my microcontroller, but the mosfet does not open enough to drive the solenoid. I have tried a few different types of logic level mosfets, but I have not had luck finding one that opens with just a 3.3V. I do know that applying 5V to the mosfet gate opens the gate enough to drive the solenoid.
I am hoping to use a logic level converter to boost the 3.3V output to something higher. Below is the circuit I am planning on using. I am hoping that this setup will work, but I wanted to hear input if I am misunderstanding something before purchasing products/soldering.
I have purposely left the resistance values off the resistors below, because I am open to input. The setup is as below:

R3 = R4 = R5 (1k ohms?) This is a voltage divider that will apply 8V to the converter.

R1 is a pulldown to keep mosfet gate low (10k ohms?)

R2 is a pulldown to keep the I/O pin low (10k ohms?)

Microcontroller = ESP32 (There is a mistake in the diagram. ESP32 is powered by 3.3V, not 3V)

Logic Converter = BSS138 (maximum High Voltage is 10V, minimum Low Voltage is 1.8V)

Solenoid = 2 amp, 12 Volt

Mosfet = IRLZ44N (RDSon is 5 Volts @0.025 ohms. Gate threshold is 1 - 2 volts). I also have some TIP120 transistors

Thank you.


texts: LPCxpresso: How to write a constant value to flash memory at programming time?

texts:
Is there a file or setting that I can add to my project that maps specific values to specific memory location in IAP flash when it is programmed? The device is LPC1114.

The use case is that each device needs a unique serial number that should be set at production time when the program is flashed onto the micro controller. Then, in my program I would be able to read it from IAP flash memory at run-time.


texts: How do you size the correct diodes for OR application of two power supplies?

texts: How do you size the correct diodes needed to OR two 12V 1.25A power supplies? What voltage and current rating do the diodes need to be?


texts: Relay Active Low - What happens with no power?

texts:
If you have a relay that is active-low connected to a microcontroller (e.g. Arduino) and the Arduino itself is disconnected from power, isn't the output pin to the relay 0V, which means the relay (if it had power separately) would activate?  Or is the input to the relay pin floating, and not absolutely at GND?

Thanks!


texts: What is the "ground strap" on a D-SUB connector for?

texts:
Take, for example, this DB-25 connector from Digikey.

http://search.digikey.com/us/en/products/5747846-4/A32126-ND/808681

Look at the features:

I understand what "Board Lock" is - the pins will puff out once inserted into the PCB so that it is held tightly in place.

The other feature is "Ground Strap".  I've tried to do some googling but I get a lot of noise regarding wrist straps.  What is it, exactly, and what is its purpose?  Why would I want/not want that feature for my connector?


texts: How do I input these types of voltages in LTspice?

texts:
How can I input:

7Vpp 2kHz 70% duty cycle pulse train with 2V DC offset
9Vpp 3kHz sinusoid with no DC offset
3Vpp 5kHz sawtooth with no DC offset

I am not sure how to put the percentages into the directive and what "Vpp" means and where to put it. I also don't know how to make the wave form "sawtooth" on the input. Showing the exact places to put the values would be appreciated.


texts: The role of reference voltage in buck converters?

texts:
I asked a question here which made it quite clear that it's probably not a good start to make something that I plug directly into the mains.

Instead, I've decided to build a low-voltage buck converter for starters. But I've run into something I don't understand.

1) You need a stable voltage to power your switching IC, or external circuit, or what have you. Usually lower voltage than the current you're trying to lower.
2) You need a stable reference voltage for your switching mechanism so it knows when it's duty-cycle is right on.

With these two things required in a buck converter, it seems you've already accomplished your end just to build the buck converter. I.E. you have to have pre-established stable, lower voltages to run a buck converter who's purpose is to produce a stable, lower voltage.

Why would you want a buck converter, and how does one establish a reference voltage and a voltage to power the switching mechanism?

EDIT

Reading both the answers I think I understand. For the switching mechanism, we KNOW the load it's going to draw and can plan accordingly. We can produce a very stable linear regulator if we know how much the load will be. We can even account for little fluctuations with a zener diode.

However, using the same process for the overall power supply would be inefficient, and if we drew too much current, the heat emanating from the components would be uneconomical. this is without mentioning that we would be unable to switch the load without getting a different voltage.

Correct?


texts: ARM CMSIS Matrix conversion to a uint16_t array

texts:
I'm working on the STM32L476RG and I'm looking to perform some matrix operations on the controller, using C and CMSIS-DSP for ARM.
I have 2 uint16_t arrays which I will be converting to matrices and feeding in to the matrix multiplication. My problem is that I need the output to be another uint16_t array, so I need a way to either convert the entire matrix to an array of the same dimensions, or a (heavier) way to access every individual element in the output matrix and typecast them into an array like array[x][y] = (uint16_t)output[x][y]
Can someone guide me through this, or is there a better way to tackle the problem?


texts: Building a short term analog memory. Would this work?

texts:
As an engineering student, I'm trying to think of an analog equivalent to a flip-flop. My goal is to have a short term memory of a signal, saturating the transistor being the trigger. Kind of like an analog D flip flop.

Here is how I hope this would work :

When Q1 is saturated, C1 quickly takes the same voltage as the input (like an RC circuit, with R close to 0).
When Q1 is left alone, C1 keeps its charge, since the input of an OP amp is supposed to behave like an infinite resistor. Since the OP amp is in a following montage, the output voltage should be the same as C1's.

So I believe this could work, but can't experiment on it. Of course I know the OP amp isn't perfect, but my hope is that it could still be good enough to preserve C1's charge for a few milliseconds.

What do you think ? Is there some obvious mistake in there that I didn't account for ? Or could this actually work ? I lack the materials to build and try this system myself for now but I'm curious. My goal would be to put it in front of an ADC in order to presample my input.


texts: Op Amp voltage output without source connection

texts:
How do I go about calculating the voltage output for an operational amplifier when the only connection to the the voltage source is through the operational amplifier itself?

For example, the diagram below has a 1.8 V source and 7 kohm resistor connected to Vp and a 1.2 V source and 10 kohm resistor connected to Vn of the operational amplifier. These sources are not bridged by an additional resistor or wire connecting either source to Vo.

I understand that Kirchoff's laws can be used to determine the output when the voltage source connects to it via a node at Vp or Vn, but I don't see how to determine the output voltage without such a connection.

Edit: The answer should be a numerical value. The hint that was given is that the op amp will saturate to +Vcc if V+ > V- or will saturate to -Vcc if V- > V+

Given this, my understanding is that this is an instance of positive saturation since 1.8 V > 1.2 V. According to Fundamentals of Electric Circuits, Vout = Vcc for positive saturation and -Vcc for negative saturation, where Vcc is the supply voltage.


texts: Break at address "0xfffa" with no debug information available, or outside of program code (TI CCS MSP430)

texts:
I am trying to learn about UART communication with my MSP430FR6989 microcontroller from TI (link), and that is a link for the User Guide (link)

The idea of my mini project is to connect the MSP430 uart_tx_pin to its uart_rx_pin, and enable the UART Transmit ISR. When  a value is written into the Transmit Buffer, a uart_tx_ifg will be set and a UART ISR will be serviced. The Baud rate will be 9600.

In order to change the system's clock, we need to write a password (0xA500) at register CSCTL0
(pg 104/1021 section 3.3.1 of the UG)
In order to write into the UART Control Registers, we need to set
UCASWRST bit at the UCA0CTLW0control register, and to clear the UCASWRST bit after we finished writing in order to enable the UART.
(pg 767/1021 section 30.3.1 of the UG)

This is a snippet of my code:

int main (void)
{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer

    P1DIR |= BIT5;
    P1OUT = 0x00;

    select_clock_signals ();//configures clock
    assign_pins_to_uart ();//assigns GPIO pins to uart tx and rx
    config_9600_uart ();//config uart baud rate for 9600
    init_uart_isr ();//enable UART TX ISR

    _BIS_SR(GIE);//enable Global ISR

    UCA0TXBUF = 0xFA;//when value is written service the ISR

    while(1);

    return 0;
}

EDIT1

Here is the code for select_clock_signals()

void select_clock_signals (void)
{
    //DCO 8Mhz select SMCLK
    CSCTL0 = CSKEY;//0xA500
    CSCTL1 |= (DCORSEL | DCOFSEL_3);//DCO 8Mhz 0x0046
    CSCTL2 |= (SELA__VLOCLK | SELS__DCOCLK | SELM__DCOCLK);//ACLK -> VLO SMCLK,MCLK -> DCO  0x0133
    CSCTL3 = 0x0000;
}

end of EDIT1

I build it and there were no issues and started debugging it with my IDE (CCS v9.2).

Stepping into the instructions inside the main function and enter the select_clock_signals () function was not an issue, when I leave the function I got this error.

I tried:

Writing a simple light the LED program in a new project, and I didn't get the error
rearrange the code so the assign_pins_to_uart() will be called before the select_clock_signals(), and I get the error when the debugger leaves the clock signal function.

EDIT2

I tried debugging my code, and at CSCTL2 = 0x0046; the value of the register automatically changes to CSCTL2 = 0x004E;. so when DCORSEL = 1, FSEL automatically becomes 7.

I don't understand why that happens, as in the UG and the Datasheet they don't mention anything about the value of CSCTL2 being changed by the MSP430.

(datasheet pg 44/183)

(user guide pg 104/1021)

end of EDIT2

Kindly assist me with this issue, your help would be appreciated.


texts: How to calculate the right motor size for a soil sifter

texts:
How would one calculate the proper size of an electric motor to properly drive a soil sifter?

Assumptions:
Screen:  flat, 18"x24", 1/4" to 3/4" wire cloth (interchangeable screens), total weight (including frame) = 4 lbs
Shake Info: total screen movement/shake = 6", shake rate = 132 shakes per minute
Load:  15 lbs soil or gravel mix
Other: Belt driven

Note:  I'd hate to use a 3/4 hp motor when all I might need is a 1/50 hp motor.


texts:
What type of switch would disconnect 3 separate lines? I just can't think of what it should be named.

If possible a suggestion of a specific item would be welcome.


texts:
I'm having trouble importing DXF / DWG into Altium.

I followed the procedure outlined in the Altium wiki
File-->Import (selected my dxf) and nothing shows up on my mechanical layer.
I've tried multiple DXF files that I have used in the past.

I'm using Altium Version 13.3.4 (Build 28908)

Any tips or workarounds ?


texts: Rising Edge vs Falling Edge D Flip-Flops

texts:
Is there any difference between a rising edge and a falling edge triggered D flip flop? For example, a falling edge flip flop will be faster or if there will be any change in result.
Is it correct for me to add an inverter right before the clock signal connect to make it falling edge triggered?
Which will be the MSB and which will be the LSB?


texts: What can I do to ensure one of my pins aren't triggered if another pin is triggered?

texts:
I'm building a "Rock, Paper, Scissors" game. The problem I'm having is when Player A selects "Rock", and Player B selects both "Paper" and "Scissors", my pin "Player B Wins" is triggered, as well as my pin "Invalid input, selected only one option".

The "Player B Wins" is triggered due to the fact that Player B selects "Paper", and Player A selects "Rock" and Rock beats Paper. What can I do, however, to make sure that Player B will not win if they select multiple options? Here is my diagram so far (It's very messy, as I am very new to logisim, gate diagrams, etc):


texts: Approaches to storing and addressing microcode for homebrew CPU

texts:
I've been teaching myself about CPU architecture for a while now and have successfully designed a couple myself. They were always based around microcode to drive the CPU's control lines.

The microcode is stored on one ROM chip and addressed by composing an address out of (1 = LSB):

Bank
CPU flag states
Instruction
T-state

Let's take my latest CPU as an example of how the address is constructed:

Bank (3 bits) - There are 48 control lines in my CPU, so I need 6 bytes to store all control line states. The bank part of the address allows me to address 6 bytes in the microcode ROM.
CPU flag states (3 bits) - I narrowed down my flags to zero, carry and compare. Need 3 bits to address all combinations
Instruction (8 bits) - The instruction set requires over 127 op-code, so I choose to go with 8 bits.
T-state (5 bits) - Some instructions take over 16 t-states to complete (complex ones like conditional CALL / RETURN) so with 5 bits I have enough room for up to 32 t-states

The final example microcode ROM address would look something like:

[flags][instruction][t-state][bank]
[000][00000000][00000][000]

Now for my question:
In the above example I seem to have reached the limit of what I can do with this approach. My microcode ROM address is 19 bits long and I have found one chip that supports it (29C040) but it seems that I don't have a lot of options if I want a large address.

I'm thinking about my next CPU which will need more flags (negative, overflow, parity) and who knows, maybe even a few more control lines or an extra bit for T-states.

What would be a better approach of storing and addressing my microcode in that case?

Only thing I can think of right now is to:

Add more ROM chips (would only free up 1 extra bit? per chip doesn't seem a good approach)
Limit the instruction set (also, would only give me 1 - maybe 2 - extra bits)
Limit the amount of control lines, but that would allow for less control over the CPU...

I wonder how this is solved in professional, microcode based CPU's and what I'm missing here.


texts: Automotive chassis is positively charged compared to earth, is this a problem?

texts:
I am working on a vehicle which has electronics equipment inside it. A neutral electrical charge of the ground connection is desired.

When I measured the negative terminal, which is connected to chassis and batteries negative, compared to the ground/earth wire in the wall socket, the voltmeter read ~ +6V DC. I also tried to measure the current from chassis to wall socket earth. The (cheap) voltmeter showed ~40 mA for a very brief moment, then zero milliamps, and the voltage difference was neutralized. Immediately after removing the current meter, the voltage difference would return to ~ +6V.

The system is: vehicle, batteries, solar charger, inverter. (and appliances but those were disconnected)

Sometimes I feel a spark when touching the vehicle while grounded.

The system is 12V. I'm not quite sure where the 6V comes from.

a) Why isn't chassis ground at zero potential? Isn't it being earthed via the rubber tires?

b) Is there a way to achieve a better earthing, e.g. a loose wire that hangs and touches the ground?

c) Is there something wrong with my configuration, or is this completely normal?


texts: Powering 12V lights from an electric fence

texts:
I have an electric fence running around my farm. I would like to be able use this to power a number of 12V lights along the road so I have a ready source of light, especially since the electric fence is on continuously.
The specifications I can find for the fence is - DC 5000 V, pulse about 500 microseconds every 1 sec, 1.5 Joules (these vary for different energisers.) (As you can see I am no electronics or engineering buff.)
Can anyone help me with the electronics to convert this power pulse into a steady 12V power supply for lights?


texts:
So I have a voltage of 8.3mV going through the op amp and want it to amplify to 1.7V. So I know I need a gain of 200. Since I need two unknown resistors, how would I work that out using the non-Inv op amp equation?
Thanks


texts:
I'm trying to use a 12 volt WiFi relay setup to control a 12 volt DC motor.  The WiFi relay has eight 10 A SPDT relays in it and the motor is 15 A.  I understand how to wire it directly to the two relays that are in the box, but I'm lost after that.  Here are my questions:

Since I'm using two 10 A relays at the same time to control the motor (positive through one and ground through the other), does this mean that I have a 20 A capacity with the relays?
How else could I wire this up to increase the relay capacity (or run the signals from the WiFi relays) to other relays and protect the WiFi relay box?

Here's the info on the WiFi relay:

http://download.carymart.com/0022001-y.pdf


texts:
I`m not sure if this is the right place to ask but: I have fried ignition circiut which is based on IGBT. I narrowed that the transistor is gone along with the emitter resistor. The datasheet for the IGBT does not show that resistor in place therefore I am having difficulty choosing the right size. I hope someone can help. Datasheet https://www.onsemi.com/pub/Collateral/ISL9V3040P3-D.PDF

This is an V8 electronic distributor. The trace goes to the IC, but the marking on the IC has been removed, I guess to protect the manufacturers from copying hence a wide issue. I have attached the Picture of the this circuit. There no similar circuit on the board to check/copy and I don't have access to anything similar.


texts: Lithium button-cell battery discharging really quickly

texts:
I am working on a board with an ARM9 (SAM9X25). On this board there is a 3.3V lithium button-cell battery powering the VDDBU power rail. It is also used with a 100kOhm pull-up resistor for WKUP with a BP.
But when my board is powered off the button-cell loses 0.001V/second, so after a few time my battery is dead...

Is it because my board is not configured for working in low power mode?

simulate this circuit – Schematic created using CircuitLab

The 3V3 comes from a buck regulator. The ARM never sleeps, but when it is powered-off (main power connector disconnected) and when SW1 is "on" the battery discharged very quickly.

Thank you for your help


texts:
this is my first question, so please be patient with me :-)

The problem is with IGBT we are using, IRG4PC40S datasheet available here> link

It has to control a 1kW heat block to keep a temperature at given level, regulated by PID based script on an atmel microcontroler. The gate of IGBT is switching with PWM on frequency 200Hz with 12VDC over 4,4kOhm resistor. Before the collector is a diode bridge with capacitor array (2mF), to give over all 230VAC phases the same power during the regulation.

It was working quite well, but sometimes it happens that the IGBT breaks trough; any ideas how to get rid off this?

EDIT: added schema


texts: Detecting 2.4 GHz signals using oscilloscope

texts:
I have used a spectrum analyzer with an antenna to see packets at 2.4 GHz being transmitted from my transceiver successfully. There was a mode in the spectrum analyzer which helps you to take a look at the power vs time plot too.

I would like to know if it is possible to do the same thing as above using a Tektronix TDS2024B Digital Storage Oscilloscope. As far as what I have understood about oscilloscope is that we need to use probes to connect it to the boards but how do I use it to detect these wireless packets?

Please excuse this naïve question.


texts: Reliable secondary storage for Raspberry Pi (or other such single-board computers (SBCs))?

texts:
Most SD cards have a fairly limited life (as in maximum number of read-write cycles), and in spite of wear-levelling, for relatively frequent disk update applications, would probably fail in a year or so, with reducing effective disk space, due to bad-blocks.

What might be some of the other secondary storage solutions, for such disk-update intensive applications, which are relatively inexpensive and not slow-coaches (the USB on Raspberry Pi, isn't very fast, as we know)?

Having said that, I am considering a USB hard-disk. Since this is a wall-powered application, power is only a secondary concern.


texts: Help Me to Identify what is the Cause for Heating with this Circuit

texts:
I built below voltage Regulator Circuit and noticed that after sometime 1K resistor is getting a lot of heat and also I connected the multi meter to Output of this circuit and adjusted preset to output 12V. after sometime voltage seems to be drop by 0.1V continuously like 11.99, 11.98, 11.97 ... etc.

What is causing the voltage drop and heating?

I provided Input to this circuit with a 15V 2A Transformer.

Source of this Circuit


texts: Turns for saturating a toroid at a particular frequency

texts:
I need to know the winding turns required to saturate a toroid for a particular drive frequency.

The toroid I have is having the following dimensions

OD = 19 mm
Thickness = 8 mm
Effective Area (Ae) = 32 sq. mm
Al (nH) = 1900
Bsat = 0.49T

My driving signal would be

f = 100kHz
Duty = 50%
Drive Voltage = 15V

From my initial research I have found that this relates to the following equation

N = (V * t) / (B * Ae)

where
V = drive voltage
t = on time of the drive voltage

Based on the above I am getting turns of 4.8

I need to know whether this is the right equation, I mean is it actually giving be the turns to drive the toroid to saturation?


texts: Signal return path between circuits with separate full-bridge rectifiers

texts:
Edit: I think I've figured out WHY this is happening (see my answer below), but I still would love to hear ways to mitigate this issue.

I've got two microcontrollers that are powered by the same dc power source, but are powered through separate bridge rectifiers and LDOs. Can these two microcontrollers communicate over UART using a single metal wire (no optoisolation) without sharing a common ground wire?

simulate this circuit – Schematic created using CircuitLab

The rectifiers in this circuit are CDBHD140L-G.

To be clear, these circuits do not share a common ground, they only have the DC voltage source V1 in common (yeah, I know rectifiers don't make much sense here with a DC voltage source; it's a UX decision that I'm not looking to change right now). Also, there are LDOs after each bridge rectifier, I've just left them out for simplicity.

My intuition tells me that

The absolute voltage levels for ground will be the same in both circuits relative to V1's negative side, so I'd expect this to be fine for DC signal transmission.
The return path from RX to TX might be impeded in a weird way by the rectifiers. I'd expect this to affect the signal integrity of the transmitted signal for things higher than a few MHz.

I've already done a small experiment, and the results didn't make sense to me. In my setup, I powered a dev board through a bridge rectifier and grounded my oscilloscope through a different bridge rectifier. I basically got the opposite of what I was expecting: the signal edges were clean and fast, but the voltage swing only went from ~400mV to Vcc - 400mV. Even worse, the range of measured voltages fluctuated by ~200mV at a frequency of ~100kHz (no switching regs on my tiny FPGA dev board afaik).

simulate this circuit

(This isn't really an oscillator pin; my dev board has a camera attached. Cause this was a quick and sloppy experiment, I just scoped one of the data pins on the camera bus hence the irregular signal.)

My questions:

Why exactly is this happening?
Do I need to provide a second ground wire between RX and TX? Would some cap-based galvanic isolation work instead?
Are there any other sneaky ways around this issue without adding a ground wire between these 2 circuits? Capacitively-coupled FM modulation / manchester encoding, etc? Some fancy bridge rectifier substitute like the LM74670?


texts: Question on capacitive circuit in practice

texts:
If we were to build a circuit, let's say with a power source of 120V AC going into a transformer which steps that up to 10kV @ 30mA, the output of which would be connected to a capacitor with a capacitance of about 3060pF, what would be happening in that circuit, especially on the right side, where the capacitor is, if 60 Hz were pumped in there through the AC source, taking into account where the circuit is grounded?

Now, theoretically from what I understand, due to the fact that the right side would act as a purely capacitive circuit, there would be "no power" because the current and voltage are 90 degrees out of phase. However, if I were to build this, would something blow or burn up or quit working, like the transformer or the capacitor or the wire? Would AC flowing through a capacitor count as a no-load situation and mess up the transformer? Also, would it be necessary to ground it twice? I'm just wondering how this would function were I to build this circuit, and what I technically should/could design better.


texts: RS232 vs USB CDC quality of service / should messages contain a checksum?

texts:
Does USB have a quality of service guarantee for data sent between my USB-CDC device and the USB host?

I know with traditional RS232 in a noisy situation (e.g. automotive diagnostic port) bad bits happen often enough that checksums are important to the protocol. If I were to adapt such a protocol to a pure-USB application, can I safely omit the checksum and related error handling routines?

For reference, I am using an AT91SAM7S256 with the USB-CDC framework provided by Atmel.

Update:

I exercised my Google-Fu a bit longer on this problem and found this article which describes a CDC subclass for Ethernet emulation and states:

  Over the USB cable, encapsulated Ethernet frames flow starting with
  the destination MAC address and ending just before the frame checksum.
  (The frame checksum is not needed since USB is a reliable transport.)

They may mean USB-CDC is reliable transport, not USB in general, since some device classes intended for high-throughput bursty data (webcam?) might not want to fill up buffers if a program can't poll for data fast enough.

I would still like additional confirmation on this.


texts: VGA timing difference in pixel frequency

texts:
I'm trying to determine what is the correct timing for 640x480 VGA. Using Tinyvga.com for 640x480@60Hz I get a pixel frequency of 25.2 Mhz and not 25.175 Mhz.

800*525*60 = 25200000

I have wrote assembly for a AVR outputing Hsync and Vsync and my logic analyzer shows the freq per frame is 60.06hz which is correct for a oscillator of 25.175Mhz.

If I use a 25.2Mhz oscillator the freq per frame is 59.94hz.

Which is right?


texts: Op amp design with both voltage and current gain

texts:
I need help designing an op amp with both a voltage gain and a variable current gain. My understand of op amps isn't perfect but I do know how to design an op amp circuit with a voltage gain and one that acts as a current source. That is relatively simple but my problem is combing them to have an op amp circuit with both a voltage gain and a variable current gain. More specifically, I need a voltage gain of 2 (5V to 10V) and a current gain of at least 300 (1mA to 300mA).
The goal of this circuit is to drive a piezoelectric actuator. I am using NI instruments that don't output enough current and that is why I need to design this circuit. My problems are as follows:
If I design a non-inverting op amp with a gain of 2 and then place my actuator across the output voltage, the actuator (correct me if I am wrong) will only draw as much current as the op amp can output. How do I design the circuit so I can drive a set amount of current to the actuator while maintaing a constant voltage gain? Could I put a potentiometer in series with the actuator to maintain the current but then wouldn't the voltage drop across the actuator? I hope I am being specific and not too confusing. I imagine this circuit will be pretty simple but I just can't put the pieces together. Any help would be greatly appreciated.


texts: What does "Brushless DC is an AC induction motor with built-in speed feedback" mean?

texts:
I found a quote
 which states that:

  "Brushless DC" is a marketing term for "AC induction motor with built-in speed feedback."

Is it correct? What is "built-in speed feedback?"

I found a decent discussion, but that doesn't clarify this question.


texts: Why is the input noise of an op-amp often lower than the Johnson noise equivalent to its input impedance?

texts: As an example, the OPA227 has 3.5nV/sqrt(Hz) input voltage noise density (at 10Hz). Its input impedance is 10MΩ, which has an equivalent Johnson noise of 1μV/sqrt(Hz) at room temperature - much larger than what the datasheet quotes.


texts: Using a triac to switch on/off a single phase AC motor

texts:
I want to use a triac controlled by a suitable optoisolator such as a MOC3020 to switch a single phase AC motor on and off, like the ones you'd find in a typical desk fan or a blender or similar.

I don't want speed control... just on or off.

I've used triacs in the past to switch resistive loads, which have worked with no problems.

Is there anything special or different I need to do to switch an inductive load? Do I need to include any kind of protection or noise suppression? If so what additional components are needed, and how are they implemented?


texts: H-bridge/buck converter with negative and positive voltage range

texts:
as already questioned here, i am still working on peltier controllers.
For that I am using a stepper motor driver (h-bridge) with a low-pass LC filter and the peltier element behind, as Olin Lathrop kindly explained. It works like a charm and is great for what it is designed for.

The schematic for that (I will add that to my older post as well):

My problem is controlling temperatures close to the room temperature. By now, I have been using the h-bridge as a MOSFET only. That means I need to decide if the Peltier is going to cool my application, or heat it up.
Since the h-bridge is capable of reversing the current I am trying to design a circuit that can go in both directions. The capacitor C1 is an electrolytic capacitor, so negative voltages would blow everything.
I thought of using diodes somehow to detect current direction, but I am not really getting it.
Can anyone help?


texts:
I have built a stereo preamp using this circuit (taken from here Hi-Fi Phono Preamp Rod Elliott - ESP), but for some reason I can't get the right channel to work at all while the left one plays.

Now I realize the circuit here is shown for one channel only, but my op amps are duals so I've connected everything the same way for the right channel. Yet it's too weak, it's almost mute. Almost all of the components I've put are exactly the same as in the circuit. The only difference is 2.7k resistor, in my PCB one channel has a 1/2 watt resistor and another is 1/4 watt. Also 22uf caps, in one channel they are 50v, in another 100v. But why would that affect anything? I've even tried different op-amps and film capacitors, but it makes no difference at all. I've checked all the connections several times. I've checked every component for resistance and capacitance as well. Obviously I've connected grounding to the vinyl player. I've tried different PSUs even, one with +8v and -8v, another with +12v and -12v. None of this helps. Another strange thing is, the moment I disconnect one of the channels from the preamp, a horrible interference appears in the other channel. What have I done wrong?


texts: Hi I am having trouble with how to find Req of the resistor network of the bjt circuit on the schematic. How can I calculate it to find Ib Vb values? thanks.


texts: Electret microphone amplifier - Terrible low frequency response

texts:
I have tried to design a amplifier for an electret condeser microphone. It is basically just a common emitter NPN amplifier.

The problem is the frequency response of the real circuit. I get the expected full response on frequencies higher than roughly 10kHz (scratching, s-sounds, crumpling paper). Lower frequencies are practically non-existent. The response I actually expect is below:

The -3db point (marked) is at around 10 Hz.

What could be the cause? Is there some major design error in my amplifier? Is it possible the microphone response is at fault or my biasing is wrong?

My schematic is below: (V1, C1 and Q1 are all part of the microphone capsule)


texts: How to make the lightning port of iphone output 5V power? like OTG on android phones

texts:
How to make the lightning port of iPhone output 5V power?

How to make the lightning port of iPhone output 5V power?

Just like the android phone, if I connect the ID pin to the ground then the phone will work as a USB host, after that it will output 5V power (the so-called OTG - On The Go usb).

  update

  I don't know why some people cast opposing votes to this the question.

  And I think this a quite normal question that many people can face. Perhaps you should check this product: Sandisk iXpad https://www.sandisk.com/ixpandflashdrive2

  I just confuse how these devices can output power by the lightning port.


texts: What is the correct way to implement left shift operations using multipliers?

texts:
I require a left shift operation to be done in VHDL. Input is 24 bit and shift amount is by 16 bits maximum.

Left shift operations by n are synonymous with multiplication with 2^n which is to say that:

  x << n = x*2^n.

Normally implementating a left shift operation in VHDL with variable shift amount shall implement a multiplexer e.g implementing a 16 bit shifter on a 24 bit input shall create a 16-to-1 multiplexer. The shift amount n will then select one of the 16 possible 24 bit outputs. This approach can create massive multiplexers that will later limit Fmax in the design.

I have found that alternative to this is to use a multiplier for the shift operation. Using a hard multiplier in place of a mux created from FPGA logic resources shall lead to better Fmax in the design. In this instance the 24 bit input shall be one operand and a 2^n where n has maximum value of 16 shall be the other operand. Here also, n is input to control the shift amount.

I have one confusion here; when using a multiplier we shall have to generate quantity 2^n from the shift amount n. This will require a look up table. In this case it shall become a 16-to-1 multiplxer where n selects the 16 bit mux output. Since we end up with a big multiplexer in this case as well, doesn't this defeat the purpose of using a multiplier?


texts: Is there an electronic device (not a speaker) that is small and can generate single tone beep

texts:
I'm new to the world of electronics and I'm working on a project where I want to create a circuit to generate a beeping sound but it needs to be as small as possible (< 6mm) to be effective in what I want it to be used for.
The speakers I was looking at are too big for what I want to do and I am having trouble finding other things to use.
Thanks!


texts:
I am trying to reduce the power consumed by microcontroller pic16f1618, and hence I thought of using SLEEP(). All interrupts such as timer, and pin are disabled. The code is generated with the help of MCC(code configurator). The function call to timer and pin initialization is commented. Microcontroller is running at 16MHz. I am measuring the current consumed by microcontroller under two circumstances.

There is just a main() function after system initialization, there is a code to read a pin inside main(). - current consumed is 8.4mA
There is SLEEP() after reading the pin in main(). - current consumed is 6.6mA

The pic16f1618 is powered through a battery management chip, bq40z60. Multimeter is placed between the voltage source of 12V and the battery chip input voltage. Hence the current measured is a total of current consumed by battery chip and pic16f1618. BQ40z60 consumes a maximum of 1.8mA.

Even though there is reduction in current consumption, it is not significant. The data sheet documents in nA. Considering the pins are not inputs, the current consumption should at least be in uA. Is there anything I need to look into?


texts: What are the differences between round and square steppers?

texts: I have managed to salvage some round and square hybrid steppers, and I have noticed that the square ones seem to be much more powerful motors. Other than shape, what are the general differences? Is one type better than the other performance-wise?


texts: IGBT vs MOSFET inverter (which is better)?

texts:
I am developing a full-bridge inverter with a working frequency of 100 kHz. I am confused about whether to use IGBTs or MOSFETs. The inverter is to output a 40V square wave signal. I have previously used MOSFETs IRF 540n with IR2110 gate driver but faced different issues and could not get the right results.
Will IGBTs work better for the required inverter configuration? Also, can anybody recommend some optocoupler based IGBT gate driver which can be controlled with microcontroller PWM signal?


texts:
I have a segment LCDs of 29 segment and a single BP.
I can display the digits as i wish with a 40 Pin PIC microcontroller.

But now my problem is to multiplex two LCDs of above type, so that i need only single extra I/O pin. But it is not working fine.

I am not able to make segments blank by configuring the BP to a high impedance state and the segment to a logic high.

AND

The segment is not blank when the segment pin is in high impedance state with a logic high in BP.

I think anyone with experience in segment LCD can suggest a good solution


texts: What is the basic difference between AM and FM radio?

texts: I want to know the basic/fundamental difference between AM and FM radio. Why nowadays FM radio has replaced AM and has become more popular?


texts: AC adapter won't power fan at full speed

texts:
I have a spare 92mm case fan rated 12V and ~600mA I've used to build a solder fume extractor. When I was prototyping it, I tested the fan with a 12V 2.5A AC adapter and it worked fine, ran at full speed, and was drawing 450-460 mA. I didn't want to tie up that AC adapter with this device, so I purchased a 12V 1A AC adapter to dedicate to the project.

I finished the project today and plugged in the new 12V 1A adapter. The fan would not run at full speed, and the speed surged up and down about once per second. I checked the adapter and it is putting out 12V, and I do have the polarity correct, and the fan is rotating the correct direction.

I tested it again with the larger adapter, and it is still drawing around 450mA, and the fan runs at full speed with that adapter.

I can't imagine what might be going wrong here. Do I have a bad adapter, or am I missing something?

Edit: I've figured it out. Turns out I had another 12V 1A adapter in an old Radio Shack kit, and it gave me the same poor result. I tried again with the 2.5A adapter, and this time checked the startup current: approximately 1.5A. The 1A adapters just can't supply enough current to get the motor to start up to full speed. I just need a higher capacity adapter.


texts:
I am using a 30V 50A power supply (KXN-3050D) as an external power source.  I have an led strip with 120 LEDs.

The problem is that when I drive 50 LEDs (in full brightness and white,) the power supply provides 1A but when I want to drive more than 50 LEDs, my power supply still provides 1A and the LEDs after 50 turn yellow.I'm going to share the circuit I set up below.

How can I solve this problem?


texts: ngspice error: too many nodes connected to instance

texts:
I'm getting the following error from ngspice:

too many nodes connected to instance

The netlist and circuit I'm modeling are shown below. Each bulk is tied to the source, so I have the sources and bulks of each transistor at the same node.

Where is the error in my netlist?

* Differential pair
*** Netlist
VDD VDD   0 dc=2 ac=0
IDD VDD  VA dc=15u ac=0
M1   VA  VA   0   0 .model nmosfet w=9u l=5u
M4   VD  VA   0   0 .model nmosfet w=27u l=5u
M2   VC  VB  VD  VD .model nmosfet w=4.5u l=5u
M5   VF  VE  VD  VD .model nmosfet w=4.5u l=5u
M3   VC  VC VDD VDD .model pmosfet w=50u l=5u
M6   VF  VC VDD VDD .model pmosfet w=50u l=5u
CLD  VF   0 10p
*** Model statements
.model nmosfet nmos vto=400m kp=200u lambda=10m tox=5n
.model pmosfet pmos vto=400m kp=50u lambda=10m tox=5n
*** Commands
.op
.end

ngspice errors:

Warning: Model issue on line 7 :
  m1 va va 0 0 .model nmosfet w=9u l=5u ...
too many nodes connected to instance
Warning: Model issue on line 8 :
  m4 vd va 0 0 .model nmosfet w=27u l=5u ...
too many nodes connected to instance
Warning: Model issue on line 9 :
  m2 vc vb vd vd .model nmosfet w=4.5u l=5u ...
too many nodes connected to instance
Warning: Model issue on line 10 :
  m5 vf ve vd vd .model nmosfet w=4.5u l=5u ...
too many nodes connected to instance
Warning: Model issue on line 11 :
  m3 vc vc vdd vdd .model pmosfet w=50u l=5u ...
too many nodes connected to instance
Warning: Model issue on line 12 :
  m6 vf vc vdd vdd .model pmosfet w=50u l=5u ...
too many nodes connected to instance


texts: What would the maximum current draw for this chip be?

texts:
I am looking at using this logic switch in my circuit:

https://www.onsemi.com/pub/Collateral/FSTD16211-D.pdf

Looking at the datasheet I am finding it hard to figure out what the maximum current draw would be.

As far as I can see, I need to supply:

5v drawing potentially up to (what)mA?

Am I safe to assume that it will be 5v and definitely under 100mA? I need to know so I choose the correct level shifter supplying the 5v!

Many thanks!


texts:
I have been working on 32-bit ARM cortex controllers writing the code from the grounds up. Now I am looking at ARM mBED OS, but few questions are bothering me. Sorry if it feels too trivial.
I have a small form factor for my product, using ARM mBED HDK will I be able to achieve it. Ex: say I have a MCU, a display and 2 sensors. To use ARM mBED there are some Hardware requirements, after making room for it will I still be able to meet the small form factor requirement.

Or can we declare mBED based products are only used for prototyping ?

I am in a phase of making a decision as to if I need to continue thinking of ARM mBED as an option or rather better pick an MCU and start configuring it. I just need some clarity on this platform wrt final product development.


texts: I have a specification sheet that says the load is 15 kW, 480 V, 3 phase. Is that 15 kW on each leg or 15 kW total?

texts:
Basically as the title asks. I am having trouble wrapping my mind around this.

If its 15 kW on each leg my thought is that you are paying for 45 kW of power but I feel like it would be more common to put down the phase power if that 15 kW was divided amongst the 3 phases.

Can someone explain this to me?


texts: Does a motor with twice the load go twice as slow?

texts:
This may be a dumb question, but I was wondering if a DC motor with twice the load goes twice as slow? If an explanation could be provided as to why or why not, that would be greatly appreciated. Thank you!

Edit: I don't know if it is important, but this question is referring to a small load that the motor can spin relatively easily (for example, 2 kg vs 1 kg)


texts: What's the highest theoretical energy density for a chemical battery?

texts:
This is more a physics/chemistry/nanotech question, but what's the theoretical best energy density you could get out of a chemical battery (or fuel cell), if you could arrange atoms in any manner you wanted?  I'm thinking of the nanotech batteries described in Diamond Age.  How does it compare to current technologies?

This is specifically about chemical batteries, which could be built atom-by-atom in the charged state, not nuclear, antimatter, CAM, or other more exotic technologies.


texts:
I am looking for ideas to implement fail-safe function in joystick control box. At present, the 5V joystick HF11S10 is connected to STM32 ADC inputs via simple 5.1k:9.1k divider. We are revising the schematics to conform to all requirements for powered medical devices, so we would like to be able to detect the disconnected or damaged wiring. With current schematics disconnected joystick results in valid 0V signal. In terms of application logic it is identical to "full reverse speed" input, which is extremely dangerous.

Note that we already solved this problem in the future projects by ordering joysticks with limited output range 0.25V-4.75V, which makes 0V signal invalid. Another possibility is to use joystick variants with digital interface available from manufacturer. However we do have a stock of old devices, and considering their price we'd very much like to find a simple solution that allows us to use them safely.

Important characteristics from datasheet:

Ratiometric output voltage 0V-5V
Output current 8 mA
Output load min 1 k
Output impedance 2 Ohm
Supply voltage range 5VDC ±0.01VDC

Also, just in case, there are couple digital inputs available and by moving things around I might be able to free one analog input.


texts: USB-C Charging Device With Agnostic Power Supply

texts:
I'm designing a PCB that will utilize USB-C to supply power (5V/3A) to my board and have a few questions:

What are the requirements to ensure a 5V/3A (15 W) supply to my device if I know nothing about the supply (i.e which default current supply case will occur if I'm charging from a laptop or other supply in which Rp is not known)?

Is it possible to ensure a 5V/3A delivery of power without a USB-C Configuration Channel Controller or USB Power Delivery IC? Ideally I'd like to implement the basic layout seen below and tap from VBUS.


texts: Maximum transmit power allowed for 802.11g

texts:
I'm learning about the 802.11 regs.  In a book I'm using, "CCNA Wireless 200-355 Official Cert Guide (Certification Guide) 1st Edition
by, David Hucaby (Author).  Page 53", it has the following clause about 802.11g.

  Be aware that 802.11g has the following limitations:

  It is used in the 2.4GHz band,...
  OFDM devices are limited to a maximum transmit power of 15 dBm, rather than the 20 dBm limit for DSSS.  This is due the way the RF
  energy is spread across the channel width.

I can't verify this any anywhere else, and it contradicts what I read earlier in the book that the FCC limits the 2.4 GHz ISM band to 30 dBm transmit power and 36 dBm EIRP.

Can anyone verify this or clear this up?


texts: How does the Infineon REAL3™ depth sensing imager chips measure time of flight for each pixel?

texts:
tl;dr: How do the REAL3™ depth-sensing imager chips measure time of flight of light for each pixel? Is it quadrature, time-to-amplitude, or something else?

The Infineon REAL3™ depth sensing imagers are used to make the Time-of-Flight (ToF) cameras in the upcoming Asus Zenphone as the "depth sensing 3rd rear camera" for Tango implementation. (additional background info)

From the drawing and discussion in the 2 page PDF I believe it uses RF-modulated infrared light for illumination. The modulation signal is also passed directly to the sensor chip serving as a time and/or phase reference.

I'd like to read about how the measurement is actually implemented within each pixel. This is what I've thought so far:

I'm assuming these are CMOS photodiodes rather than CCD pixels, so one possibility would be to do some kind of quadrature detection, and simply report phase. The problem here would be the ambiguity if the round-trip time is greater than one period of the modulation. The sensors have dynamically adjustable modulation frequency, which I suppose could be used for "auto-ranging". Also, the quadrature method would require at least approximately sinusoidal intensity variation of the LED.
Edge-detection (time to amplitude conversion) could be used instead of quadrature. That would would with rectangular wave modulation.
To get rid of super-period time ambiguities, a more complex digital code could be used instead of a square wave.

Considering they've added a microlens array to the imager to improve light collection, the application is probably S/N limited. In the situation of a phone, you're lighting the scene up to 4 meters away with a flashlight running off of your cellphone. To get sub-nanosecond precision with fast update, the battle is noise. It's possible the method with the best inherent S/N performance would be the best choice.

In all of the above, I'm assuming the infrared light is from a single uniform source flood-illuminating the scene, without any grid pattern or structured light.

The highest available modulation frequency is currently 100 MHz. With a period of 10 nanoseconds and the speed of light of about 30cm/ns, that means at the highest frequency objects at a distance of 150cm would be at the ambiguity limit. But dropping to 30 MHz would work for the rated maximum distance of 4 meters.

So far all I've found is the two page PDF linked above, but no data sheet or in-depth discussion.

Can someone explain: how does the Infineon REAL3™ depth sensing imager chips measure time of flight for each pixel? I'm looking for the definitive answer, not idle speculation. However, educated, contemplative speculation is certainly welcome if no answer is forthcoming.

above: screen shot from the 2 page PDF.


texts: Choosing series resistor for Optocoupler LED

texts:
How do you choose the series resistor value for the LED side of an optocoupler. My application uses this opto to interface a button that is about 25meters(50 meter wire roundtrip) away from the device.

For choosing R44 or the collector pullup was pretty easy since the datasheet has provided a 1k. On the other side however there is no mention of a resistor. I would like for the led to be able to take inputs from at least 3.3 to 12volts.
And having a look at the input characteristics of from the datasheet the maximum forward current is 60 mA(for a typical LED this is very very large). What would be the minimum current of the LED for so that the PIN can still safely register an "ON" state. Would a higher current(lower value resistor) on the led (30-40mA) be safe for repetitive use?
Going further, to skip using a voltage regulator (it will come from mains anyway) is it possible to use the mains voltage 240 VAC instead since the optocoupler is capable of using AC anyway. How would I choose my resistors then ?