texts: Gain of proportional Controller with distubance \$sin(10t)\$

texts:
The diagram below represents the position of ocean oil platform system which use the proportional controller with gain \$k\$. The output \$x(s)\$ is the platform deflection regards the position desired. Consider the platform initial position \$0\$ and it subjects of waves forces the sea, which effect could be represented for disturbance \$d(s)\$.

a) Determine the transfer function \$x(s)/d(s)\$ in terms of \$k\$ and \$G(s)\$.

b) Consider the Bode diagram below with respect of \$G(s)\$. Suppose that it apply a disturbance as unit step function (\$u(s) = 1/s\$). What the amplitude of deflection, in steady state, of platform in respect the position desired in function of gain \$k\$?

c) Consider now that the disturbance would be the sine signal on time domain given by expression \$d(t) = \sin(10t)\$. Determine the value of the gain from proportional controller \$(k)\$ for, in steady state, amplitude of deflection of platform in respect the position desired been equal to \$0.1\$

  I really think that I've solved correctly the letter a) and b) but i have theory doubts about the letter c)

a) \$x(s) = -x(s)\cdot k \cdot G(s) + d(s)\Rightarrow \frac{x(s)}{d(s)}+\frac{x(s)\cdot k \cdot G(s)}{d(s)} = 1\$

\$\boxed{\frac{x(s)}{d(s)} = \frac{1}{1+k \cdot G(s)}}\$

b) We need to value \$x(t\rightarrow\infty)\$? but \$e(t\rightarrow\infty) = \underbrace{\text{input}(t\rightarrow\infty)}_{=0} - x(t\rightarrow\infty)\$

\$e(t\rightarrow\infty) = -x(t\rightarrow\infty)\$

\$E(s) = R(s) - x(s) = -x(s) = -d(s)\cdot\frac{1}{1+k \cdot G(s)} = -\frac{1}{s}.\frac{1}{1+k \cdot G(s)}\$

\$e(t\rightarrow\infty) =\lim_{s\to 0}s \cdot E(s) = \lim_{s\to 0}s\cdot-\frac{1}{s} \cdot \frac{1}{1+k \cdot G(s)} = -\frac{1}{1+k\cdot G(0)}\$

\$G(0)|_{db} = 6.25\$

\$ \boxed{x(t\to \infty) = \frac{1}{1+k \cdot 10^{\frac{6.25}{20}}}}\$

I stuck the letter c)

Consider \$\mathscr{L}(sin(10t)) = \frac{10}{s^2+10^2}\$

\$e(t\rightarrow\infty) = -x(t\rightarrow\infty)\$ (same idea that letter b)

\$E(s) = R(s) - x(s) = -x(s)\Rightarrow e(\to \infty) = \lim_{s\to 0}s.-d(s).\frac{1}{1+k\cdot G(s)} = \lim_{s\to 0}s\cdot-\frac{10}{s^2+10^2}.\frac{1}{1+k.G(s)} = 0\$

Seems something I've missed this part.

Can someone give me any hint?


texts: Charging multiple (rechargable) LIR2032 (similiar to CR2032)

texts:
I have no experience with creating any type of chargers, so maybe my problem might seems naive. I'd like to charge multiple LIR2032 3.6V Li-Ion rechargable batteries.

What current, voltage and time is needed to charge:

5,
10,
20 of those.

How should I connect batteries to charging PSU, in parallel or in series?


texts: The maximum voltage that can be applied to the inputs of the comparator TLV1805Q1?

texts:
I'm creating a circuit with a comparator TLV1805-Q1.

Question: what maximum voltage can I apply to the comparator inputs and what is the maximum voltage difference between inverted and non-inverted inputs?

In the table, I found this:

I did not understand this wording.

Is it permissible for this comparator to supply 2.5 V to the inverted input and 5 V to the non-inverted (Also PWM 0-5V signal)?
The voltage difference between the inputs reaches 2.5 V.

Circuit:


texts: Why is a lower Noise Figure considered better than a higher Noise Figure?

texts:
I'm trying to understand why a smaller Noise Figure is supposed to be better. The conventional definition for N.F. is the ratio of SNR(in) to SNR(out). This can further be broke down as follows:

\begin{align}
  N.F. = \frac{SNR_{in}}{SNR_{out}} = \frac{\frac{P_{sig,in}}{P_{noise,in}}}{\frac{P_{sig,out}}{P_{noise,out}}} = \frac{P_{sig,in}}{P_{sig,out}}\cdot \frac{P_{noise,out}}{P_{noise,in}}
\end{align}

If we want a low noise figure, that means we need a low SNR(in) and a high SNR(out). So does this mean our final objective is to always try to make our SNR(out) as high as we can so that our signal is amplified much more than our noise?


texts: Braking down amp tubes schematics (EL86, ECC83, ECF80)

texts:
Hey I got schematics for the tubes in the title. What are the values in the black circles (for ECC83 and ECF80)?
EL86: What do the shapes with the numbers inside them represent? What do the numbers in them describe?


texts: Wheatstone bridge: Modifications for different temperature sensor resistance

texts:
I am trying to build a Wheatstone circuit to detect temperature changes of a low resistance (about 10 ohm) wire.
For a first try I would like to use a circuit proposed in this Maxim Application Note 6144
How to Linearize Wheatstone-Bridge Circuit for Better Performance, Figure 7:

I am a beginner in using and understanding schematics. So in general I have two questions for the beginning:

As stated, the circuit in figure 7 is an example to be used with a PT1000. I guess that's why R1 and R3 were chosen to be 1k Ohm? What needs to be changed if R3 is only 10 ohm for example?

In the example, some capacitors don't have values. Some are names C_FLY, C_FELT, C_HOLD or don't have a name. Can you guys explain to me why they are named like that and what values would make sense in this circuit?


texts: How can I power Beagle Bone Black with 3.7V LiPo?

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I want to power this board with a 3.7V LiPo battery (due to small form factor) such as this.

Would I need a step-up DC converter or something? And where on the BBB would I connect it?


texts:
I am using the C027 development board for prototyping an application and I was wondering it it was possible to use the Tx and Rx pins of the GSM module (available on the pinout of the board as P0_15 and P0_16) to communicate with another microcontroller on another board (like the MSP430 Launchpad).

I think that it is not possible as both ends have to share the same clock in order to be synchronized but I therefore do not understand why they put these pins on the pinout.

Is it possible in my situation to communicate by UART without having the same physical clock connected to the two components ?


texts: I don't understand the outcome of the solution for a circuit with two voltage sources and an inductor

texts:
I have solved this circuit problem and I don't really understand the result in terms of power for the two sources.

So for source one, it is clearly generating real and reactive power.
For source two, it is consuming, based on the current going out of the source.
The reactive power consuming reactive power.

The results shows the new power in the circuit is almost zero.
But the reactive power is not zero, the consumed is way more than the generation and that does not make sense.

Is there a problem with my math?

Thanks in advance for your help.


texts: Can I use a single AAA battery to power a motor?

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Can I use a single AAA battery which has 1.5V and 700mAh to run a stepper motor which has operating voltage 3.1V and draws 1.2A/phase?
If, yes then how many minutes will it run?
Someone briefly explain if possible.


texts: Output coupling capacitors in dual-supply op amp circuits

texts:
Consider a dual-supply op amp circuit used to process (but not amplify) line level audio; for the sake of simplicity, imagine a unity gain follower. With the input AC coupled and referenced to ground, only a small DC offset, caused by the op amp, will appear at the output and this seems negligible at the first glance.

In this scenario, is it necessary to also put a coupling capacitor at the output? Here are some of my thoughts so far.

Pros of having an output coupling capacitor:

If a later stage is DC coupled and has gain, the coupling capacitor would prevent the DC offset from being amplified.
If a fault develops within the device and the op amp starts outputting a rail voltage (or any substantial DC level for that matter), the output capacitor would prevent this condition from negatively affecting later stages.

Cons of having an output coupling capacitor:

Since the input impedance of a later stage is unknown, a fairly large capacitance is required to achieve the desired low-frequency response.
The capacitor would have to be terminated with a resistor to ground. To avoid loading the output, it would have to be a high value resistor and this would introduce additional noise at the output.

Is there anything I'm missing here? As much as I'd like to omit the cap and the accompanying resistor for obvious reasons, I really wouldn't like to design a product that causes trouble for its users and interacts badly with other devices.


texts: How to protect an electronic construction kit (a toy) from damages?

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As I child, I had this electronic construction kit called Elektronik 1. It was manufactured in former Czechoslovakia, based on resistors, diodes, BJT transistors, capacitors, an LW+SW radio antenna and an earphone. It is quite simple, very good for children like 8 years old. It was originally powered from a 4.5 V battery (3 x 1.5V).

Now I try to recover the kit. I realized that diodes are all dead, some transistors are dead; all the other parts seems to be okay (including all those 30 years old capacitors). The original parts from eastern Europe aren't manufactured anymore, but it was easy to find some similar replacements. But the main question now is: Why those parts were damaged and how to protect them from another damage? When children play with this stuff, they can do many stupid circuits, because they are simply curious what will it do. So please tell me if you have got some tips what can be done there to protect those semiconductors from damages. Or at least a little bit.

The problematic parts are:

BJT transistors, I use BC546A and BC556A now.
Rectifier diode, I use 1N5817 now - it has 1 A limit, hopefully it helps.
Signal sensing diode, I use 1N5711 - this one is very sensitive.

Besides the semiconductor parts, I also want to use AC/DC adapter instead of quite expensive 3R12 type 4.5V battery. Of course, I don't know current limit of the original kit - how many amps do I need to replace a battery? I think 0.2 A could be enough. I now use an old Nokia charger. It is rated 3.6V 0.33A 1.3VA, but it is actually unregulated and gives up to 10 volt without load with audible 50 Hz noise when used for an LF amplifier. I think I will add a large capacitor and LM317LZ to regulate it down to 4.5 volt. I hope that LM317LZ will also act as a safe current limiting device which can possibly also protect the semiconductors from future damages.


texts: How dangerous is this broken lithium-ion laptop battery?

texts:
The wife’s laptop is an older Macbook with a dead battery (i.e. it wouldn’t charge, but used to run fine when connected to an outlet). With the wife in hospital the thing wasn’t used for a while now (and not connected to power). Today I noticed that the bottom plate was deformed. When I removed it I saw that the battery was bulging. While I was watching the battery case cracked open (either because the bulging was still in progress or because the pressure from the backplate was removed).  I live in a fourth floor apartment without emergency exits, so I am a bit more than usual concerned about fire hazards. Also I'm clueless about electricity, thus I called the local fire brigade for advice. They recommended that I should throw the battery into a bucket of water to cool it down.

So my first question is, is this the proper thing to do? The internet is in two minds about this, one half saying NOOOO! because lithium (which is what I would have thought) and the other half saying there is no metallic lithium in a lithium ion battery, so that’s not a problem.

In the end I did not do it, amongst other things because there is still a computer attached to the battery - despite using the proper screwdriver  the screwheads had sheared off when I had tried to remove it. At the moment the whole thing is sitting in a ceramic pot, wrapped in a watertight bag, in the middle of the back yard, which has a concrete floor.

So my real question is, how dangerous is a depleted lithium-ion battery (I have no idea if the danger depends in any way on the electric charge)? In the unlikely event that the thing will not be stolen overnight I want to remove the battery and salvage the rest of the computer. The only way to get it out will be to break off the latches for the screws, which means I have to hack away a few millimeters away from the bulging battery cells. Is that even remotely safe ? Do I need protection (I should have plastic goggles and gloves lying somewhere)? Or do I worry unduly, and this im completely harmless?

There is a rather similar question, but since I specifically need to break the case of an already damaged (and cracked open) battery this does not quite help (also I’m really curious about the „cool batteries in water“ thing found an answer to that). Also I hope somebody can recommend sensible precautions.


texts: Prevent spurious triggering of NodeMCU GPIOs

texts:
I designed a simple circuit to control a relay with a NodeMCU micro controller. The NodeMCU polls a remote web service via a simple API and pulls high or low the D1 GPIO according to what it's posted online. The relay is triggered accordingly.

I used a 2N7000 MOSFET and a pull-down resistor (78K) to keep the GPIO low if floating. I'm not sure if I also need the other 4.7K resistor to limit the current through the base-source path of the MOSFET, I couldn't risk frying the NodeMCU so I added it.

Here my initial schematic:

The system works as expected. Unfortunately the NodeMCU drives the GPIOs high for a very short period of time during boot (I measured 50-80ms or so). I don't have control of this behavior because it is before my firmware starts running. The short pulse is enough to trigger the relay and I'd want to avoid that.

I tried adding a small capacitor in parallel with the pull-down resistor. This way I solved the issue as the capacitor filters out the short spike and then discharges quickly if power is lost.

Here's the fixed schematic:

It works very well but I don't know if that's the correct way of doing things. Is it ok to do so? Does it stress the GPIO in any way? Also, do I risk letting the spike through if I quickly power cycle the NodeCPU? (I mean, does the capacitor discharge quickly enough?)


texts:
I am designing my very first PCB for a robotics project I am working on. The project will be using through hole components.  I was not able to get all the traces to work on 1 layer, so I added a second layer, the board layout is shown below:

Given this board layout, will I have any trouble using through hole components?  Will I also need to solder the components to the leads on the top layer (red), as well as to the leads on the bottom layer (blue)?

EDIT

I've updated my board design below, adding 0.1uF caps to both VSS/VDD pairs on the pic, and increased my trace widths to 30 mils, while also hopefully reducing the trace lengths.  The following board also passes the DRC check:

I still can't get the ground plane to show up for whatever reason.  Any suggestions on how to improve this would be appreciated.


texts: Driving a 12V-24V 20 ohm solenoid from a 24V 0.5A input signal

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I had a question about trying to get a solenoid with 20 ohms resistance to power up from a 24V Power supply limited to 0.5 amps.
I tried connecting a 10 ohm resistor in series, to drop the driving voltage to 16V, but I ended up burning the resistor. The valve did work properly before the resistor burned up though. Is there a higher amp resistor part-number search I can get somewhere?
I know I should use a relay and drive this as an alternate circuit, but this is a field application, and I don't have the resources to create even a tiny panel atm... Any help would be appreciated, the goal is to get it working :D
The application is driving a valve which is connected to the SMC EX600 valve pack DYPB output card. Manual here.


texts:
While picking up LiPo battery for my project, I've seen that there are two different types: small and inexpensive one, like this one here that can be charged with a simple circuit like this one. And there are big ones like this one here  that require special expensive charger like this.

Why is it like this, if the internal chemistry workings are the same? Why do they need special chargers when the unit cell has the same nominal voltage?


texts: How to run hair trimmer's motor normally (without pulsing) using 12V/1A charger? Its orignal cell battery uses 1.34V and 0.34A

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I want to run a small DC motor (which is operated on a 1.2V 600 mAh cell battery) using 12V charger. Now the problem is that when I connect the motor to 12V, 5V, 3.3V the motor starts pulsing (I mean starts for 0.5 second and turn off for 0.5 seconds and the loop keeps on), but when I connected 3.7V 18650 cell battery directly to it, the motor start to rotate at full speed. Furthermore I connected the motor to 5V power supply but again the power supply turns off and on again repeatedly. Last but not least, when I connect the terminal of power supply to one of the terminal of motor due to sparking it start rotating normally, but without sparking it keeps on pulsing.

Kindly tell me how to run the motor smoothly and what components should be used? Basically I'm trying to power Kemei Hair Trimmer using 12V charger.


texts: How should I translate old TIG statement from UCF to new Vivado XDC files?

texts:
I have a short UCF file with the following content:

## Fan Control
## =============================================================================
##  Bank:               15
##      VCCO:           1.8V (VCC1V8_FPGA)
##  Location:           J48, Q1
## -----------------------------------------------------------------------------
NET "FanControl_PWM"    LOC = "BA37";           ## Q1.Gate; external 1k pullup resistor
NET "FanControl_Tacho"  LOC = "BB37";           ## J48.3; voltage limited by D2 (DDZ9678 - 1.8V zener-diode)
NET "FanControl_*"      IOSTANDARD = LVCMOS18;

# Ignore timings on async I/O pins
NET "FanControl_*"      TIG;

This file bounds two physical pins to two top-level ports. Additionally, the I/O standard is set to low-voltage CMOS 1.8 V, because bank 15 is sourced with 1.8 V.

To reduce warnings in Xilinx ISE (trace) I specified that all timing paths to and from these pins should be ignored (timing ignore -> TIG).

Question:

How can I translate TIG into Vivado's XDC syntax?

What I discovered so far:

set_false_path is only for internal paths and
set_disable_timing seams to be very special


texts:
This is probably a silly question but I figured this might be worth another question instead of adding it onto my other one.

Referring to this question (About an SR latches first Q state)
What is the beginning state for Q in a SR latch?

Lets pretend we have an AND gate (or really any kind of gate).
Inputs with A and B and Output Y.

Now lets pretend I send a Signal to A and B. What is the Output of the gates Initial Value? Like is Y always set to 0? Like when the computer is first turned on?

Like for example a NAND is 1 when both inputs are zero......so we do always assume the NAND gates output is 1 like when we first turn on a computer, or it receives it's first signal?

or for instance lets say a NAND gate for instance, and I send a 1 through input A, and a 1 through input B.....lets say (for some reason) the A gets there faster.....is the output 0 for a second then switches to 1....or was it 1 before (since technically both inputs were zero before?)

I guess looking at the transistor diagram might make more sense, but I guess the "timing" of Gates and SR latches has me a bit confused at what the outputs are "initially set" to.


texts: TVS DIODE: Min breakdown voltage and Stand off voltage

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Can anyone of you please help me out ?

I have a doubt about the TVS diode characteristics,(V-I).  I am listing my questions below

What is the min Break down voltage
Stand off voltage
why VBr> Stand off voltage??


texts: Pulse Transformer design problem: cant understand for sure whats the reason or irregular output waveform?

texts: A ferrite core pulse transformer provided with 12V PWM signal (as primary winding input voltage) as shown in Fig-1, produces irregular output voltage across the secondary winding as shown in Fig-2. I dont know why the ferrite core pulse transformer is doing like this; is it due to saturation of ferrite core pulse transformer or maybe low inductance of transformer primary winding? Pulse transformer winding ratio is 1:1


texts: electric motor diagnostic and troubleshooting

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I put my hands on vintage Dewalt radial arm saw. from the radial arm saw community its probably manufactured on the 40's.

The motor is single phase and connected to 220V (this is the default line in my country).

The motor is really old with several layers of paint so the info label got deleted over the years.

the motor is connected from the wall outlet through a contactor and to the motor.

the wires connect on the motor back plate and from there split to two wires (probably to two separate windings. two of the wires have continuity with two wires that shows on top of the motor (for capacitor?)

when trying to start the motor (without the blade) it runs without capacitor but seems slow on startup.

some more findings:

the rotor has no centrifugal switch.

the rotor is also missing its fan for cooling

it seems that the windigs got rewound sometime over the years.

My questions are:

1) How can i know what size of capacitor do i need?

2) How can i know if the capacitor is start capacitor or run capacitor? start windings or run windings?

3) what should i need to understand from the fact the motor has no centrifugal switch?

3) If the capacitor is only start capacitor how can i turn it off after startup without centrifugal switch?

Thanks


texts: In this diagram, can the op-amp be used as the error detector? Can it compare the load position to the input position at CX and produce an error signal?


texts:
I was reading a datasheet for a Murata DC-DC converter Murata DC-DC converter. It has the following LC filter recommendation to reduce output ripple:

As the output voltage of the DC-DC converter goes up, the recommended L value goes goes up and the C value goes down so that the cutoff frequency stays roughly the same at 20kHz.
Why would C be traded for L as the voltage output increases as opposed to keeping the L and C values the same for all voltage outputs (since they all provide the same cutoff frequency)?


texts:
Why does this work?

simulate this circuit – Schematic created using CircuitLab

But this doesn't.

simulate this circuit

In the second schematic, V2 is adjustable.

Is there a better (not very complicated) way to make an adjustable current source where the LOAD is between Source (transistor) and GND (not with the sense resistor connected to GND and the LOAD on the high-side)?

Does the op-amp have to be powered with a dual power supply?


texts:
Does displaying black screen (but not turned off), consume less power than a white screen? Or is the screen just blocking light to show a black pixel and not blocking for not showing it?

And, if I go to the command line in Linux (tty3), would the monitor spend less energy?


texts: Can someone help me design a circuit that will open when power is applied and close after power is removed?

texts: I am using an air conditioner thermostat transformer which provides power to my circuit. When the thermostat powers up, the door opens. I want the door to remain open until the thermostat shuts off, then I want the door to close. I'm using a solenoid to operate the door. The Transformer is 24 volts reduced to 6 volts. How can I keep the door open as long as the thermostat is operating then close once the thermostat ceases? I have exhausted my knowledge base and hope help may be found here. Thank you for examining this project. -Kegbuster


texts:
I need to control a load that uses 20A at 110v. Should I use solid state or mechanical relay?

Mechanical relay's contacts can lose conductivity over time due to high current and high voltage, I am just not sure, are solid state relays more reliable at high voltage & high current?


texts: Question on TWO stage power conditioning

texts: Suppose a induction motor is connected through a inverter. Inverter is fed from a DC-DC boost converter. My question is: to boost converter how load current will look like? Will it look like DC or AC?


texts: Altium doesn't let me place components the way I want

texts:
I have a problem when placing my components on the board. altium restrict my movement. It is like some design rule are not showing up but blocking me to put components the way I want.

I think I have activated a function but I don't know which one who make that I can not place components the way I want.

Edit:
Does anybody knows what I have to change ?

When I try to place a component A close to another one B, the compnent A can not go closer to B. It is same than like a design rules apply making that I can not place the way I want. Altium block the move as if there is a clearance between both components. Normally the DRc would turn the component green. Here it doesn't turn green it just block the move

It is typically avoiding or blocking obstacles...


texts: Help with understanding transistors in circuits

texts:
The picture above is a circuit for a hearing aid, so we need sound amplification.
BC547 is NPN, BC557 is PNP. How is the amplification happening, why is it connected so?
Edit: I found a circuit for sziklai pair amplification.

Looking at my original yellow circuit I can't understand why the rightmost BC547 is connected as it is. I see that the output is obtained from the emitters of the pair in sziklai pair ckt. Why is the BC547(rightmost) added to emitters of the sziklai pair and just inserted in between?


texts: reading a 1000 Hz (sample freq) signal using 200 Hz sample frequency

texts:
I wan't to read a signal using my Arduino Pro Micro. The signal is produced from a sound file on my phone, the output from the phone passes through an offset circuit to lift it to be read by the Arduino. My Arduino is set to sample at 200Hz (fixed), but my audio signal has a 1000 Hz sampling frequency. How is reading the 1000 Hz signal using 200 Hz sampling frequency going to affect my data? I've noticed that the time measurement is out of order (1000 samples don't mean 5 secs anymore from the received data from Arduino). Can someone help me understand this point?

My signal's max frequency is 80 Hz, so I think 200 Hz is okay.
My concern is the received sampling frequency. I send the time of the sample with every sample so that I verify the sampling frequency. When I used real sensors with this same Arduino and 200 Hz fs, I got the right fs received, but know it's different. I mean 1000 samples should have 5 seconds worth of data if fs=200 Hz but I got 2.558 seconds. That's what I need to understand.

Thanks


texts: Derivation of Transfer Functions of Second Order Active Filters Resource?

texts:
We have covered the transfer functions and operation of some second order active filters (using op amps) in my electronic circuits course. However, the professor presented us with the transfer functions rather than derive them. I like to see a derivation of transfer functions so as to gain a better intuition for them when I first learn them and, strangely, my book (Sedra and Smith's Microelectronic Circuits 6th ed.) doesn't offer a derivation/proof either.

Does anyone have a resource that can show me the derivation of one or more of the standard filter types? Or is it possible someone could walk me through a derivation? I would really appreciate it!

For example, the Low Pass Filter's transfer function was given as:

$$\frac{Vo}{Vi} = \frac{H_o}{1 + \frac{s}{w_o \cdot Q} + \frac{s^2}{w_o^2}}$$

where \$w_o\$ is the fundamental frequency and Q is (I assume?) a quality factor of some sort.


texts:
I'm building an Arduino switch for two different signals and I'd be very grateful if you can revise the schematic and tell me if there's something wrong or if something can be improved.
In the schematic you can see two switches (representing two different Arduino GPIO pins) with a 1k serial resistor to limit the current according to Arduino's datasheet.
The labels represents an unknown external circuit. The only thing I can say about it it's that the BJT transistor is connected to a low-power high-frequency (~870kHz) circuit, and the MOSFET is connected to a 5V high-current (~3A) circuit.
The circuit should be on if the Arduino isn't placed (thus open circuit on GPIO pins), that's why I placed a 10k pull-up on the base of the BJT transistor.


texts:
I want to replace the potentiometers in my electrical bass due to scratching. All three of them (volume of pickup 1, volume 2, tone) are of the same kind, "US 250KA" single-turn (no push/pull).

Is this regular 250K, or does the "US" or the "KA" stand for something special?

I don't want to change anyting, I just want to put the instrument into its originla (non-scratchy) state.


texts: How do I convert a signal of 3v to 2v to a signal of 0 to 5 v

texts:
I'm measuring input voltages between 2v and 3v (3v volts corresponds to a reading of 0 and 2v corresponds to a reading of 10,000) on the analogue in of my arduino. I would like to measure the voltage at the highest possible resolution of the arduinos A/D converters.Using an operational amplifier and common resistors how would I convert a voltage range of 3V - 2V to a corresponding 0v - 5v for the arduino inputs.

I tried Using the simplified method on this page
Scaling Voltages With Op amps

|Gain| = Output Range / (Vin.max â€“ Vin.min)
so gain would be 5

Gain = Rg / Rin so  Rin = Rg/Gain
picking a 10k resistor for Rg i get Rin as 2k

Voff = Vin.max * ( |Gain| / ( |Gain| + 1 ))
so 3 * (5/(5+1) -
this part confuses me, I would think that the offset is simply 2 because I know that the lowest voltage I need to measure is 2V

Voff = Rbot / (Rtop + Rbot) * Vref

and here is where I get lost


texts: How do I make a low-noise computer case fan adaptor cable (using a resistor)?

texts:
I have a Noctua NF-12x25 5V fan, used in a custom Raspberry Pi case, that's a bit too loud for my taste. Noctua sells low-noise adaptor cables for 12V their fans that, from what I understand, are just cables with an in-line resistor. I know almost nothing about electronics. How would one size a resistor and make such a cable based on the 5V fan's specifications?
Aside: I'm checking with Noctua whether this particular fan will actually run/start at 3.3V but I'm assuming it will.


texts: Will a BJT blow up if there isn't any load/resistance either in collector or emitter?

texts:
Taking NPN BJT as example.

When an NPN BJT is operating in the active mode, \$I_C = \beta I_B\$. That means we can fully control the current pass through the BJT by controlling \$I_B\$ only. In such case, as we didn't place any load/resistance along either collector or emitter, which means \$V_{CE} = V_{CC}\$. Therefore, as a result, the BJT would have \$I_C = \beta I_B\$ and \$V_{CE} = V_{CC}\$, this looks fine!

So, does it mean that a BJT won't blow up if there isn't any load/resistance either in collector or emitter?


texts:
I am designing a USB device and I can't find easily the USB specs about the maximum current consumption allowed for the D+ and D- lines.

I am planning to use a 39Ω termination resistor on this lines, and the ones I find in resistor networks of 2 are 0603 62.5mW. If I assume a 3.3V connected to a short to GND (improbable, but maybe good practice to make a more reliable system) this will be (3.3 / 39) * 3.3 = 297mW. So if I can estimate the maximum current consumption of this lines, I might check if 63.5mW are fine or not.


texts: Simulating Pulse Induction Driving Circuit in Proteus Errors

texts:
I've been trying to simulate a pulse induction driving circuit in Proteus to no avail. One issues appears to be with how I am using Proteus and the other seems to be a simulation or setup error that I can't figure out.

The system complains about the current probe placed at the top of the inductor. It keeps throwing an error stating that the current probe is ambigious and for the life of me I can't figure out how to fix it or what I did wrong.
If I do get the simulation to work the current flowing from VCC doesn't have a sharp drop off like I would expect once the MOSFET opens, instead it slowly declines which seems to affect the discharge of the inductor, even though the MOSFET should be open.

Another strange part of the simulation is when I remove the flyback diode and disconnect the right hand circuitry for measurement, there is not large flyback voltage spike. It only goes to -6V and then slowly decays back up followed by a sharp snap back to 0 once the slow current decay finishes.

Any advice as to what I am doing wrong?


texts: Correct negative current measurement but incorrect positive measurement

texts:
I'm trying to replicate a simple circuit that I designed in SpiceIV. Here's what it looks like

I should be getting ~23 mA of current flowing through this circuit by ohm's law. However, when I measure it using my multimeter if I connect the COM lead to the positive side and the INPUT lead to the negative side I get a result of around -23.5 to -25 mA, which falls within the tolerances of my multimeter.

However, if I switch the leads and put INPUT to positive and COM to negative like I should I get a reading of exactly 13 mA every single time. I cannot for the life of me figure out why the current measurement is correct going one direction, but not correct going the other. I've checked the fuses (~0.8 ohms average when I touched the leads together) and checked my math 100 times.

Can anyone with more experience than me shed some light on this problem? I don't understand it at all. For all intensive purposes SpiceIV shows current in the negative which means my reading is "right", but shouldn't I be seeing the same number going the other way?

EDIT: For clarification I am measuring the current with the multimeter in series with the rest of the circuit.


texts: Possible timing issues with Microchip RN2903 LoRa module?

texts:
Is anyone using the Microchip RN2903 LoRa module?

This module is soon to be replaced by the RN2903A module due to the fact that the RN2903 didn't go to sleep properly. Microchip also re-tuned the crystal oscillator inside the module, although they claim the crystal tuning doesn't affect the RN2903, only the RN2483.

So my problem is this: I have two boards, each have an RN2903 on it. These boards are used as transceivers in a communication link. Board A attempts to establish communication by sending a 19 byte message to board B (point to point communications using the LoRa modulation). If board B receives the message it is supposed to respond with a 2 byte response message. The problem is that this handshaking doesn't complete at room temperature. I have been able to determine that board B gets the original 19 byte message but board A doesn't get the 2 byte response.

If I apply a small amount of heat to the RN2903 module on board A the handshake will successfully complete right away. So, I'm pretty sure that board B is always sending the 2 byte response but board A will only receive the 2 byte response if it is warm enough.

Just wondering if anyone else has experienced similar issue with this module.

UPDATE...

Thanks to anyone who took some time to puzzle over this question.

Microchip has acknowledged a flaw in the firmware that was loaded on this module at the time of purchase. That version of firmware was 095. The problem was that the SPI interface between the MCU and the LoRa xcvr inside the module was configured incorrectly. For some reason this incorrect bus configuration was sensitive to temperature. Microchip recommended that I update the firmware on my module to the latest version, that being 098. I am attempting to do this to verify that new firmware does indeed fix my problem. Will report the result when I test....


texts: Turning an old digital point and shoot camera into a webcam

texts:
I have an old 5 megapixel Sony Cybershot DSC (I think it's this one) lying around somewhere, and since it is pretty much obsolete (but it shoots great quality 640x480 video) I keep wondering if I could hack it and use it as a webcam somehow.

Did anyone ever attempt to do such a thing? The camera has a usb data transfer cable and a composite video out but you probably can't screw with the software to feed video through those while you're shooting it. But how hard could it be to leech live video off of some point on it's way to the memory card or something?

I have some experience with arduinos and whatnot but I have a feeling that you shouldn't need one to pull this off.

Don't know much about how cameras are wired though. What do you guys think?


texts: What screw should I use to mount a TO220 package?

texts: What screw size should be used to mount a TIP31 in a TO220 package to a bare PCB (no heatsink?) I presume a nut will also be required on the other side, so would appreciate a part number for that too. (I'm not too clued up on mechanical stuff, so go easy on me.)


texts: N-array of monitored old lead acid batteries with solar panels

texts:
I would like to build a system of a arbitrary number of old and different specs. lead acid batteries (recycled) working with a solar regulator (mppt or pwm, doesn't matter).
The initial idea was to put all batteries isolates with a schottky diodes for charge and for load, all the time.
The second idea is use a thyristor rather than a diode: lower drop voltage and you can cut if the battery is out of parameters: volt, amps, aH over total or temp (monitoring with a small plc).
The third idea is the same as second, but the charger is not from a common regulator, it is a individual charger per battery: 3 steps regulator for this kind of batteries (bulk, charge and float).
Any better idea? Thanks in advance.


texts: Oscilloscope high impedance ground more noise?

texts:
If I setup the two situations in the diagram below one where a scope is connected to the output of an SMPS, and one where a resistor is placed between the grounds of the scope and the supply (which is isolated). I notice that the switching spikes/ noise becomes more and more prominent as I increase the resistance.
The fact that signal degrades as the ground gets weaker isn't alarming, but I haven't got my head around which path this noise comes from as the ground connection falls away. Some insight would be appreciated!


texts: Confusion about the meaning of re and rπ

texts:
In BJT small-signal models there is both re and rπ parameters. They both represent the dynamic resistor between the base and the emitter terminals.

But I read that they are different by a factor of β as:

  rπ = β × re

I know the concept of transconductance gm. It is the slope of the  Ic Vbe plot at a fixed bias collector current i.e: gm=∂Ic/∂Vbe.

And as definition re = 1/ gm.

So what I understand is that re is the change in Vbe with respect to a change in Ic.

Secondly rπ is the change in Vbe with respect to a change in Ib.

Since there Ic = Ib × β this yields to  rπ = β × re

You might think what is my question here. Even though the formulas yield this relation between  re and rπ, I don't quite understand how they represent the same thing aka the "dynamic resistance between the base and emitter terminals".

I mean their definitions are same but yet they are different things. They are both the dynamic resistance between the base and emitter terminals in my mind. But they differ by a factor of β. I'm really confused about the approach. Is it about where we look at the base from?


texts: Simple UA741 inverting amplifier not Working

texts:
I'm building a simple non-inverting amplifier using UA741,The gain should be of about 11,and the input is 500m v dc so the output should be in the range of 5.5 volts however i'm getting about 0.45 volts.I'v tried changing the bais voltage many times from 15 to 32 volts but the result is the same.

PLease Help....


texts: How do I know where to place resistors on my circuit?

texts:
Some of the books I have state that power comes from the negative terminal on the power supply.If that is the case, the circuit starts from the negative right?

Say I have a simple circuit with a 6v supply, an 1K resistor and an LED. If I wire the resistor to the positive source, then wire that to the anode of the LED and back to ground, the circuit works fine.

How can this be the case? Shouldn't the resistor be between the cathode and the negative source?


texts: Why do typical DC motors use brush contacts rather than just conductors?

texts: Why do typical DC motors use brush contacts rather than just the conductors of the wire itself? Wouldn't the wires be more efficient/low wattage dissipation in that region?


texts: A device used to logically turn on a circuit with voltage being the input parameter

texts:
I’m working on a project which utilizes a power-source which is liable to vary. I have a micro-controller sitting at the output of an LDO (Low Dropout Regulator).

I’m concerned about the LDO outputting a voltage below its fixed output if a voltage below specified input range is applied to it. Low-voltage could potentially damage my micro controller and disrupt the logic of the circuit.

Ideally, I’m looking for a device capable of operating under a wide voltage input range -- one that can compare an analog voltage value to some number I programmed into its “memory”. If the voltage input is greater than or equal to that number, it should produce an output which would allow the rest of my circuit to turn on. Basically this device would work as an external under-voltage lockout device, ensuring that my system operates within specified voltages.


texts:
I am currently working on a project where we use TIVA C TM4C123G and I am currently getting inspired by launchpad as reference design. I have several UART peripheral to connect to the main chip using UART, however on the pins of the chip RTS and CTS are only marked on the UART1.
How I am supposed to deal with this ?


texts: how to implement an integrated rechargable battery in my project?

texts:
i'm constructing a simple portable speaker/amplifier and want it to contain am integrated rechargeable power source.

What's the best/safest way to integrate a rechargeable battery?

i want it to work much like an electric shaver or mobile phone would, with a transformer integrated into the plug, and with a coaxial power connector used to transfer electricity to the unit.

thanks.

battery type: probably ni-mh i think? i need something with plenty of ampere-hours, but am concerned about making it safe enough to leave charging overnight. also i need a simple and cheap solution!


texts: Don't reversible 2 prong plugs have to account for orientation?

texts:
I don't know much about electrical hardware, so forgive any naivety.  Anyways, I've been wondering: since 2 prong plugs (the reversible ones whose prongs are the same size) can be plugged into a socket two different ways, don't they have to include more complex circuitry than their non-reversible 2 prong brethren to allow for the electricity flowing two opposite directions?

If so, then why do manufacturers do this?  Is it just cheaper, or is it motivated by consumer convenience?

Based off of the relatively small sample of plugs currently available for my investigation, it seems to me like most reversible plugs are found on charging devices (e.g.: phone or laptop charger, which all have the colloquial "brick" included), while plugs built into electronics and other hardware (e.g.: a power cable for a TV or a lamp, none of which have an external "brick") do tend to have 2 prongs, but these are differently sized, rendering the plug non-reversible.


texts:
I'm working with Page Flipping and Tiled Rendering (all hardware based) but i cannot understand one aspect of page flipping technique.

When you're at frame 1, you're rendering bank1 and working on bank2 for instance. Then you start rendering frame 2 and switch to render bank2 that you was working. Until there, all okay, but when you start working on bank1 again, all changes that you done on bank2 arent on bank1.

How do Page Flipping works without copying content from bank2 to bank1, since do a full copy (like Double Buffering) its impossíble only in vsync time for my applicaition.


texts: How to improve my curve fitting for an LED in spice

texts:
I have an LED that I'm working with, actually it's not a discrete part but on silicon.  Anyway all I have is a curve for it and I was trying to work up a spice model in LT-spice.   I followed this question and tried two methods from there with Martyn's python method giving me the best results.

For LT spice I took the three parameters he puts out and made a model statement:
.model led D
****DC Model Parameter***
+is=1.87E-17  n=9.275
+rs=5500

Which gives me a curve that is close to my original data points at low voltages but diverges at higher voltages like so:

Orange is the measured data and blue is the model.

I've tried adjusting the parameters manually for a few hours but I can't seem to get something that matches the higher end.  I feel like either I'm missing something or maybe I need to add another element other than just a diode?  I seem to remember opening some professional models and seeing a few components inside.

How can I make my model match my actual datapoints better?


texts: How to drive a video signal (of any kind) to a CRT monitor? What's the protocol, interface, standard, convention, etc.?

texts:
Say I am going to develop a video displaying computer componenet (call it a TTL chip, GPU, whatever).

There has to be some basics on how to communicate with the monitor, or how to make sure the data sent to it will agree on its side.

Basically, what are the specifics here? Assuming I want to just put something (on the monitor), what assessment protocol is required? What type of interfacing must be done? Does data/signal have to be sent a certain way? Any documentation on this?

Bear in mind that, yes, I am a beginner to all of this, especially EE, but a detailed answer is preferred more than a "you don't know enough" one would be(simply because I can understand deeply technical terms much easier than the "experts" would think).

Clarification: No, no LEDs, LED matrix displays. Also, I'm not asking how to BUILD a display, but how to INTERFACE with a specific display(CRT monitor).

Sorry if this seems too "wide of a question", and I don't mean to insult any experts here (just stating prior that some experts think anyone without a degree can't do what they can, or are very short/rude with some beginners asking genuine questions about interfacing components etc.).


texts: Passive band-pass filter conceptual analysis

texts:
I'm trying to chain a high-pass filter and a low-pass passive filter together to form a band pass filter to illustrate how you can combine filters together, but I'm having issues trying to understand it mathematically.

Consider the following schematic:

simulate this circuit – Schematic created using CircuitLab

Conceptually, I'm taking the output of a high-pass filter (with corner frequency formed by L1 and R1), putting it through a low-pass filter (with corner frequency formed by R1 and C1), and taking the output. It should work as a bandpass filter, but when I try to work it out mathematically, I get the following equation (right now, not taking into account actual values but just working it out conceptually):

Let \$Z_1 = R_2 + Z_C\$ and \$Z_2 = Z_L || Z_1\ = ((Z_L*Z_1)/(Z_L+Z_1))\$

\$V_{MID} = V_{IN} * Z_2/(Z_2+R_1)\$

\$V_{OUT} = V_{MID} * Z_C/(Z_C+R_2)\$

\$V_{OUT} = V_{IN} * (Z_2/(Z_2+R_1)) * (Z_C/(Z_C+R_2))\$

\$H(\omega) = (Z_2/(Z_2+R_1)) * (Z_C/(Z_C+R_2))\$

Expanding out transfer function yielded the following:

\$H(\omega) = (Z_LZ_C) / ((R_1+Z_L)*(R_2+Z_C) +R_1Z_L)\$

In this form, it almost mathematically works out that the output of the bandpass filter is just the transfer function of both the LPF and the HPF multiplied together, but that bottom addition term ruins it. From what I've read, I'm not accounting for the effects of load impedance on the output/inputs of the filters, which may be the cause of what I'm seeing here. If that's the case, assuming that \$R_1=R_2\$, what can I do with L and C to make this BPF work as expected?

EDIT: Sorry for not being more specific enough. What I'm looking for in my bandpass filter is to pass frequencies within a certain range, as dictated by the corner frequencies of the HPF and LPF. Relatively straightforward. If you would like some numbers, let's go with corner frequencies of 5 kHz and 10 kHz. Ideally, I imagine my BPF to pass all signals with frequencies from 5 kHz to 10 kHz, and attenuate all signals that fall outside of that range. I'm just trying to demonstrate a very simplistic concept of the bandpass filter by combining filters together.


texts:
I am wondering, I made a MIDI circuit and was advised to use ferrite beads in my device for MIDI input/output. It is a similar to the following circuit (only the L1/L2 ferrite beads are important for my question):

However, in most USB cables, there is a ferrite bead inside the cable.

If it is advised to use ferrite beads with MIDI, why aren't ferrite beads standard inside the cable? Or otherwise, why do USB cables use ferrite beads, and they are not within the USB device/adapter?

Below is an example of a USB cable having a ferrite bead (I assume) on both sides; btw, most generic USB cables do not have them, this cable is for charging a mobile telephone.


texts: dsPIC33 ADC: Why is the minimum TAD interval such an oddly-specific number (117.6ns) for 12-bit conversion?

texts:
I'm writing the firmware for a data-acquisition board using the dsPIC33FJ64GP804 MCU and I noticed something strange reading the electrical characteristics for 12-bit A/D conversion:

The ADC clock period (emphasis mine) is listed as 117.6ns, which is an oddly-specific number, especially considering there's no direct hardware obstacle to try running your ADC much faster, e.g. with TAD = FCY, which could be as low as 25ns at the highest officially allowed clock speed. So the limit doesn't come from there.

The characteristics for 10-bit conversion seems more like it's been derived from actual characterization testing:

So where does this weird value come from? Something related to the settling time of the sample&hold capacitor (esp. considering TSAMP = 3 TAD for 12-bit and TSAMP = 2 TAD for 10-bit)?

Edit

To clarify, I understand TAD = 25ns would be asking for trouble. My main questions are:

Why is TAD different for the 10-bit and the 12-bit case at all?
Where does the 12-bit number come from, could IC characterization (which I guess involves statistical methods and uncertainty) really produce a number that precise?


texts:
I'm attempting to record 8-bit/8kbps audio to an SD card using the samd21g18a microcontroller. I'm having an issue where the ADC sample value drops whenever the SD card is being written to. This results in a "ticking" noise during playback.

The "ticking" happens at a ~60ms interval which is consistent with SD card writing after buffering 512 bytes (512 * (1 / 8000) = 0.064 seconds). I've shortened all the wires to their minimum lengths which has reduced the amplitude of the "ticking" significantly, but it still faintly exists. Does anyone have any suggestions for shielding the mic/ADC from noise from the SPI lines?

Here is a screenshot of the audio file in Audacity that shows the "ticking" sound. This was before I shortened the wires so it's not quite this severe anymore:

For the mic, I'm using this Adafruit breakout built around the MAX4466, which seems to be picking up and amplifying the noise from the SPI lines.

Thank you!

@JRE Here is a diagram of the setup. Again, the lines are kept as short as possible with both breakout board grounds connecting directly to the Feather M0 ground pin.

@John Birckhead I initially thought that power to the mic might be dropping while the SD card is writing due to the higher current demands. Here is a screenshot of VCC (CH1) and the mic output (CH2) while it's logging to the SD card. The input voltage seems very stable even upon zooming in.

Here's a screenshot of the SD shield clock pin (CH1) and the mic output (CH2). The resolution isn't great, but you can see that the mic output drops then recovers when the SD write happens.


texts: What affect does charger wattage have on lifetime of LiIon batteries?

texts:
This questiuon is generic to LiIon and LiPo batteries but a Mac is used as an example.

A Mac 'laptop' is provided with a 85 Watt charger.
It is possible to charge it with 45 Watt charger that was supplied with a different Mac 'laptop'.

The 85 Watt charger charges the battery from 0% to 100% faster than the 45 Watt counterpart.

But, does using a higher power (wattage) charger impair general battery life in the long run?


texts:
I was implementing a simple circuit on an FPGA using Quartus (6 logical elements) and I noticed that the block containing the 6 cells is located near the perimeter.
Is this a general criterion? The placing on the border can help to minimize some delay? (i.e. is it "nearer" to the output pins and this is beneficial)


texts: Testing an Audio Power Amp with Paralleled Transistors

texts:
A question concerning my current repair project of an audio amp that uses big (600 W) but otherwise rather classic complementary output stages:

I assume when testing an audio power amp with 6 pairs of paralleled npn/pnp transistors, it is o.k. to assemble just 1 pair while testing as long as you have no significant output load connected. The advantage would be that, while testing, I would not blow as many of the precius MJ15022/23 transistors I have available as spare parts.

In what ways (if any) will the bias current circuit be affected?

Any problems I may not have considered but may be important for this repair technique?

Any other really good tricks for fixing big amps?

Once I am closer to finishing the repair: Does 10...15 mA of bias current per transitor branch sound like a good number to you?


texts: Building a High Current Power Supply? (Odd Voltage)

texts: I'm working on a project involving some custom LiFePO4 battery modules. They can take a very high current charge, and I'd like to take advantage of that. I have battery management and charge termination equipment that I've built or hacked together, and now all I need is a power supply to drive it all. I need 28.8v (±0.1v) with at least 30A. Since this seems to be rather difficult to come by (and fantastically expensive when you can find them), I figured I could build my own. But designing such a thing is beyond the scope of my knowledge. Can one of you guys help me, or at least point me in the right direction? Any help or advice would be greatly appreciated.


texts:
I've seen multiple different explanations on boost converter circuits, these two specifically explaining in very intimate detail how they work, and on how to calculate certain values:

How to design a boost converter? And how to specify the inductor and capacitor values?

Understanding Boost Converter

the basic layout of a boost converter looks like this:

simulate this circuit – Schematic created using CircuitLab

In this example, the 1 volt input would be increased to a higher voltage across the resistor, which would be the load in this case.

Problem:

I need to switch a 5 volt current on the high side with an NPN switch (for many reasons this is the only switch layout available, no other layout will work as desired), so I need 7 volts to the gate to switch it, however only 5 volts are available. For this I need a boost converter that will convert 5 volts to 7 volts to be able to switch the switch

But, I'm not sure how to calculate any of the values. For example, the solutions in the links I provided use the switching time of the switch, how can I find that? What size inductor and capacitor would I need?

Also as an aside, the thing labelled "L" on the diagram, the inductor, what is it's purpose?


texts:
I recall seeing a web-based HDL synthesizer a couple years ago, but I can't find it anymore. I believe it was just a frontend that ran the vendors' synthesis tools on the server.

Does this sound familiar to anyone? I don't remember the name, and nothing is turning up in my searches. (Perhaps it got taken down?)


texts: Using MOSFET to turn on/off auxillary electronic circuit

texts:
I have custom-build e-bike which is basically a motor, battery, controller and an LCD screen with 3 buttons. When I push ignition button, the LCD sets voltage on one of it's signal wires (blue) to 51 - 67.2V (BAT+, depending on battery capacity) which is then wired to the controller.

I would like to sense voltage on this ignition wire and switch on/off an external dc-dc converter (8-72V to 5V5A) in order to charge my phone while riding a bike. One downside is that I can't pull too much current on this signal wire - dc converter need to be wired directly to the battery by mosfet or something else.

After 3 minutes of idle, LCD automaticly turns e-bike off (0V on ignition wire) which is okay, i want to charge my phone only while riding.

I need a solution that uses no power when switched off in order to not drain the battery.
I'm thinking of using a MOSFET as a switch where this ignition wire would be connected to the gate of MOSFET. As far as I understand I need a MOSFET with Vgs of at least 67.2V? Could anyone point me at a right mosfet? Wiring schematic and any tips on this would be great too. Thanks!

PS. Added schematic of my wiring


texts: Question about communication using a controller area network (CAN)

texts:
I am trying to make a test CAN loop on a breadboard and I want to try reading and writing to it using an mbed.

I found an example circuit and some test code for reading and writing from a CAN loop using mbed. However, if you look at the test code you can see that it writes from Pins 9 and 10 and reads from pins 29 and 30. From what I read about so far this is called writing to one node on the CAN loop and reading from another node.

CAN Handbook

But I am wondering if it is possible to take turns both reading and writing just from pins 29 and 30? I think this would be called writing and reading from the same node on the CAN loop. Unfortunately I don't think I can do that from what I read about so far. One source I found says...

  Every node can see all messages from all other nodes but it can’t see its own

found on page 3 of CAN Primer: Creating Your Own Network.

I did try to test reading and writing from the same node by creating the circuit on a breadboard and changing the code from can1.write to can2.write. But the message was never received. I wonder if that is because my changed code is incorrect for reading/writing from one node.

But intuitively it seems to me that the message should be able to loop back to the sender. Since I don't know that much about CAN, I wanted to come here and see if anyone knew the answer to my question...

Can I make a test loop reading and writing from the same one node (just pins 29 and 30) on the mbed?


texts:
In my project I want to set the configuration of the RTC based on the reset source. If a reset is done via hardware reset NRST, the RTC shall be set to zero.If there was a reset due to wake up from standby or shutdown mode, then the RTC configuration should not be erased. (I think, in that case I have a software reset of the core). This can be achieved via RCC register which stores if the reason of the reset.

How can I detect whether the controller was reset via SWD Debugger?

The debugger should not reset the RTC in my case. I found nothing about that in the reference manual. My specific model is the STM32G071, but I think that question might apply to most of the STM32.


texts: How to avoid electricity to pass through inverter output socket but output socket will always be connected to electric line?

texts:
please pardon me if I have written a duplicate question, but know that I am a novice.
I have a DC to AC Inverter which used to give me 220V 500W AC output. But when I connected the output side with the electric connection and when the connection expecting that it would automatically start to provide the electricity. But unfortunately the inverter got damaged due to connecting the output socket to the electric line while output socket was serving electricity.
What can I do to ensure that the inverter output port will always be connected with electric line, but the electricity will flow towards one direction only, fron the inverter to electric line?


texts: Circuit Simulation for a circuit that take a 10KHz input

texts:
I can't seem to get the amplitude right can someone help me.

Using the Circuit Wizard circuit simulation software, devise a circuit that
takes as input a 10 kHz square wave of 1 V amplitude and uses a
series resistor/capacitor combination to ‘shape’ (take the hard
edges off) the waveform.Choose resistor and capacitor values such that approximately two-time constants have elapsed.


texts: How to identifiy this "2222 063 90025" vintage capacitor?

texts:
I am restoring an old stereo valve amp and would like to test (and replace if needed) some components.  I don't know the history of the amp, but it's made in New Zealand and looks to be from the 1960's or 70's, but I could be wrong.

There are a couple of capacitors that need identifying.  The first and larger one is clearly marked 50 \$\mu\$F, however, it has three legs.  What I would like to know about this capacitor is:

Do the three legs signify a 2-in-1 capacitor?
What does the product code of 2222 063 90025 signify (tried here, but no luck)?
What do the triangle, square and circle symbols indicate?
How do replace this capacitor?

Capactior product code:

Capacitor from below, with 3 pins:


texts:
Is there a reset board available (I mean schematic, link, tutorial or anything else) out there for the ATmega32 microcontoller (I heard about a high-voltage reset board, and I found some links for an ATmega8 reset board, but not ATmega32)?

I actually have many dead microcontrollers here (with a wrong fuse bit configuration), and I want to make some board to reset them to their default configuration. (I'm not able to program them because of a wrong fuse bit configuration).


texts: Small ripple in 555 timer output when connected with a 2nd 555 timer chip

texts:
I have two 555 timer chips.  The 1st is used to create a transition every .1 seconds while the 2nd is used in a monostable configuration to debounce a button. When using my DLA to look at the output of the debouncing 555 timer, I am seeing small spikes in the output that correspond exactly with the frequency of the output of the other oscillating 555 timer.  I have attached my schematic showing my interconnections. Note the schematic shows connections to a terminal block. However, in my breadboarded version I have a 100K Ohm resistor tied to positions 7 and 8 of the block and a button tied to 5 and 6.

It is also the case that the LED's along with current limiting resistors or NOT in my current circuit when I am doing this recording.

I have also attached a screen shot of the trace from my DLA.

The 555 timer I am using is the SA555 chip.

Any thoughts on how to prevent this would be greatly appreciated.


texts: What is the current source for in the Schmitt trigger?

texts: What is the current source for in the schmitt trigger? I can't understand this. Can't see any resistor either.


texts:
I am new in the field of electronic circuit simulation and the two articles i am reading from

http://en.wikipedia.org/wiki/Electronic_circuit_simulation
http://en.wikipedia.org/wiki/SPICE

have led me to ask this question.Supposing i am running an analog and digital simulator like LTSpice analog and digital simulator,can i have an LED display inside the LTSpice analog and digital simulator to display some data for instance if i am working on a data acquisition circuit?.


texts: What happens if you drive the output of a LM78CT05 when the input is not connected

texts:
I have a Fairchild LM78M05CT (datasheet) as a 5V regulator for a µC circuit that also has an ICSP port.

The actual circuit is the one in this question: Review of my first ever PCB design for a watering control robot.

I've seen some versions of the 7805 regulator data sheets where the application notes recommend a diode from Vout to Vin in order to protect the device from burning out if the output voltage goes higher than the input. However the datasheet to the Fairchild LM78M05CT doesn't show such a diode in the application notes. Hence I assumed it wasn't necessary with their implementation.

I went to program my device through the ICSP port so I disconnected it from the DC power (Vin to regulator unconnected) and applied +5V and GND to the ICSP header to power the target µC (which drove +5V to Vout of the regulator).

The programming failed, and the target device has a "electronic" smell not present before. Also a LED on the Vin side of the regulator shines indicating a current from Vout to Vin. When I next plugged in the DC cord I got a spark from the ground terminal (and there is a black residue from it on the solder mask) of the DC plug and immediately unplugged the DC cord.

Further I measure (in situ) only 500R or so between the Vout and GND pins on the regulator both ways which is much less than what I would have expected.

So my questions are:

Is my regulator shot?
Did I actually need the diode from Vout to Vin (would that have protected my device) in order to be able to program with ICSP?
Should I have had the DC power connected to the target? I would have to have had 5V and GND between the target and programmer (arduino working as ISP) to ensure matching signal levels so I would have had two +5V drivers.
Any other measurements I should make?

Status Update: Appears that I also bricked the DC adapter, LED doesn't come on and no voltage on terminals. Desoldered the regulator, all pin combinations with polarity measure within tolerance of a new one and it doesn't smell. Applied 5V over ICSP again with DC plug removed and no regulator mounted, smell came back and power LED lit up indicating RL1 is providing 5V on pin 11 in the circuit linked up top. Also the relay smells funny.


texts: how can the frequency response of Matlab plot differ from the calculated one?

texts:
I have here a circuit of butterworth 2d order with a cutoff frequency of 38KHz from calculation:
    fc=1/(2*pi*sqrt(R223*R225*C190*C191))=38.73146646102262e+03

but in matlab, the plot of the transfer function gives me another different cut off frequency at -3dB

R223=1.6e3;
R225=3.9e3;
C191=820e-12;
C190=3.3e-9;
Anti_aliasing=tf([0 1],[(R223*R225*C190*C191) (R225*C191+R223*C191) 1]);
options = bodeoptions;
options.FreqUnits = 'Hz'; % or 'rad/second', 'rpm', etc.
figure('name','2d order butterworth filter with 38khz');
bode(Anti_aliasing,options);
fc of bode plot=47e03 Hz

I have the same value and the transfer function seems correct. what am I missing?

here is the schematic:


texts: Inside of Razer USB-C Charging Cable Layout

texts:
maybe you can try and help ,
i got Razer Blade Stealth 13.3" QHD+ Touchscreen Ultrabook,
my charger that is 65W with 20v with 3.25a for 20v,was broken at the end of the conector at the end of the charger and when i opend to see what USB C type is it i saw 4 red lines and one blue and one more line ,
see attcehd photos and maybe you can help what needed for solder on a new C type
Thanksenter image description here


texts: OP AMPs : ADC Buffer on voltage divider plus protection

texts:
I have been reading lots of threads in the past but I have some questions which are still not clear to me. Please help me out in this!
Picture of circuit is attached.

So basically I am using ATmega328 to read a photo diode. I have built a trans-impedance amplifier using the photodiode, and OPAMP AD712 (I am considering OP07C as well). The trans-impedance amplifier uses 9-10Mega Ohm resistor with 15 pf capacitor to convert the current from the photodiode to voltage and add some gain to it.
I understand that this follows the Ohms Law i.e. V=I*R where R = 10 Mega ohm and I is the current generated by the photodiode (in nAmperes). The OP AMP AD712(first in circuit) has 2 OP AMPs in built. For simplicity, please see OP AMP naming convention below:

1st OP AMP's AD712's internal first OPAMP: *OP1A
1st OP AMP's AD712's internal second OPAMP: *OP1B
2nd OP AMP's AD712's internal first OPAMP: *OP2A
2nd OP AMP's AD712's internal second OPAMP: *OP2B

I then pass this voltage to another OP AMP (OP2A - new AD712 which leaves the second OP AMP in first AD712 unused) using variable R1 and R2 resistance to get a gain on -(R2/R1). Note that the voltage from previous OPAMP was negative, thus after the gain, it becomes positive.

Up till this stage, we have used one opamp from 1st AD712(OP1A) and first opamp from 2nd AD712 (OP2A).

My first question is that if I use both op amp of the first AD712, then will it cause any issue? Can one opamp in an IC affect the other opamp(s) in the same package?

Going forward, I feed the gain output to a buffer by using OP1B. I understand that not all opamps are happy in unity gain (buffer!?) configuration. The AD712 data sheet specifies that it is unity gain stable.

The output of this buffer then goes into a low pass filter using 1K in series and 1uf in parallel to ground. The effective impedance (or simple DC resistance) is 1K.
This signal then goes into a voltage divider using another 1K in series and variable pot of 2k in parallel. I have set the variable to 1429 ohms because when the input comes as +12 volts, the output of the voltage divider should give me 5.001 volts. I am effectively converting the 0 - 12v from opamp (gain) to 0  to 5 volts.

Question: I understand that voltage divider with these resistances will be fairly linear. Is this correct?

I also understand that I lose the resolution, as the ADC can read 0.0049 volts as-is (10bit ADC with vref = 5v) which means that the ADC should be able to read 0.01volt difference when voltage is divided (.01 at input will be 0.0040 at divider and .02 will be 0.0090 at divider).

I then move this signal to another buffer (as I don't want the impedance of my divider to play any part in signal deviation and I want no loading on the divider so ensure maximum linearity. More advantages are listed below) OP2B and plan to read it via the ADC. I see this as an advantage because I can now setup another low pass filter just before the ADC input without worrying about the effective resistance exceeding 10K which is stated as the maximum resistance at the ADC input in the datasheet of ATmega328.

Note that I plan to put schottky diode in with +5 at (-) side to provide protection to ADC.

Now my few questions:

Does the above sound logical or am I missing something fundamental?( I am sorry this is my first electronic project and I am a programmer!)
All Op Amps are rail to rail with supply of +12 and -12. What if I supply +5..+5.5 to last buffer op amp so that its output never exceeds its rail which can allow me to skip the schottky diodes?
How much gain can I get from DC perspective without any problems?(I tried to understand the gain-vs-frequency charts but I cant get it. DC is 0 Hz or 1 Hz)
Should I put some bypass capacitors on signal line? e.g. after trans-impedance amp , put a small cap in parallel to let the high frequency signal (noise) to ground out...
*If the above response is yes, then how do I decide the value of Capacitor such that it does not cause delay in my signal?


texts: IR modulation with photodiodes multiplexing

texts:
I have 100 IR photodiodes that I would like to multiplex to one (or the fewest achievable) transimpedance amplifier(s), both for space and price constraints.
I am aware of the capacitance and noise issues due to the distance between the photodiodes and the TIA, explained in this answer.
I am looking for a way to increase the signal to noise ratio.
As I am in control of the IR sources, I am wondering if modulating the source as explained here can help filtering some of the noise after the TIA.
However as I am already multiplexing the photodiodes at 100Khz (each photodiode should be read every millisecond), I am not sure of which modulation frequency could be used to help reduce noise, or if it would be achievable at all given that the TIA would need to handle the choosen frequency (its Gain BandWidth Product, and slew rate should be rated accordingly).
Do you think that modulation can be benefical in this case, at which minimal frequency ?


texts:
I need to press and hold key 1 and than press key 2 to increase value.
How to Read keys only if both keys are pressed. This is what is have which is not working correct. (programming languages vhdl).

if key(0) and key(1) are pessed do somthing

PORT (
KEY : IN STD_LOGIC_VECTOR(3 DOWNTO 0);
);

SIGNAL A, B, C, D : STD_LOGIC_VECTOR(1 DOWNTO 0);

BEGIN
A <= KEY(0) & KEY(1);
B <= KEY(0) & KEY(2);
C <= KEY(0) & KEY(3);

Readkey: process(KEY)
begin
if (A = 1) then
D <= "00";
if (B = 1) then
D <= "01";
if (C = 1) then
D <= "10";
end if;
end if;
end if;
end process;


texts: CD4011BE (DUAL INPUT NAND GATE) not working

texts:
I am using my CD4011BE NAND Gate IC. I connected a 9V battery in the 14th pin. And grounded the 7th pin. Then I provided input in the first 2 pins. I took a 330 ohm resistor from the third pin and connected an LED with that resistor and then grounded the other side of the LED.

I checked every possible configurations of the 2 inputs {(0,0),(0,1),(1,0),(1,1)}.
But the outputs are not as expected. The LED never lights up.

I changed my IC and used another one of these CD4011BE and got surprised to see that this time the LED always lights up.

I am new to making circuits and electronics. So excuse my mistakes and please point them out.


texts: How to trigger multivibrator (or similar) from collector?

texts:
How to chain one transistor's output with another circuit (multi-vibrator
for example, but may be some other sound generating circuit on discrete transistors)?

The R1-Q1 with addition of a 1k resistor and LED works fine from collector: LED is ON when I connect R1 and OFF, when I disconnect it.

Now, I want to produce some sound with a multivibrator, when R1 resistance drops to 1-2m. The latter just does not work from collector!

(Of course, multivibrator works fine when Q2 and Q3 emitters are connected directly to ground).

Maybe, there is a better way to control circuits like multivibrator from collector?

UPDATE: R1 is MegaOhm, sorry for typo.

UPDATE 2: Thanks to hints from JIm Dearden, the circuit following started to (somehow) work:

However, I am going to implement better (and more general solution):
Schematics for device, which reacts to water?

Disclaimer: any mistakes in the circuit are solely mine.


texts: In absence of leakage, what creates the angle between stator and rotor flux in an induction machine?

texts: As per my understanding to produce torque from a machine, we need an angle between stator and rotor flux. In an induction machine rotor flux is created in response to stator flux, why is there an angle between rotor and stator flux?


texts:
in forward bias, when the holes enter the n-region and when the electrons enter the p-region, the recombination happens and the carriers annihilate each other.
so how does the net current generate?
on the other hand the direction of electrons and holes flow is opposite, i would like to know what is the direction of net current?


texts: Help identify positive, negative and ground on a LCD screen PCB

texts:
Let's just say I know nothing about electronics, so please bare with me on improper terminology.

I have a LCD screen that I have disassembled as I am trying to make a Touch screen mirror fit into a metal picture frame. The LCD included power adapter jack/plug is currently protruding from the back of the picture frame and therefor I would like to cut the cord on the power adapter end and solder the wires directly to the PCB (and the hot-glue to isolate).

It should be easy to cut the end of the power adapter and measure with a multi-meter which wire is positive, negative and ground.

However, I am having trouble finding which point on the PCB is which.

I have removed the plastic part of the jack on the PCB (image below) and was hoping this community could help me figure out which wire from the adapter should be soldered to which point on the PCB?

The large part of the image below shows the top where the plastic jack housing was. Once the jack was removed the PCB shows the markings 1,2,3 and a plus sign (the - on the large picture is the number 1 and not a minus sign). The number 3 is where the center pin from the powere adapter plug would go. Number 1 and 2 are touching.

Can anyone help me understand which is the positive, negative and ground on the PCB?

Here is a before picture before removing the plastic jack from the PCB:


texts:
Is the system y[n] = x[n] + x[n-1] invertible?
If yes, what's the value of x[n]?
If no, could you please introduce a counter example?

I couldn't find any counter example so I assumed the system is invertible and then tried to generate x[n] in terms of the output y but it always lead to a signal depending on a previous input.

x[n] = y[n] - x[n-1]

x[0] = y[0] - x[-1]   --- 1

x[-1] = y[-1] - x[-2]  --- substituting into 1:

x[0] = y[0] - y[-1] + x[-2],

and so on.. the resulting signal will always depend on another input. Does this imply non-invertibility of the system? if yes, do I not need a counter example?

Note: this isn't a homework question.


texts: Our DC Motor gives high Current at relatively low load. Why?

texts:
I am a Drilling Manager working on a Drilling Rig. Currently we are facing a problem that's been baffling us for sometime.

Through my extensive experience and we have data to prove it. A DC motor can easily PULL load upto 150 Tons at 750amps. However, now it can hardly pull 100 tons at 1100 Amps at the same exact resistance

So what could be the problem?. And yes we have change the DC motors twice, now we have a brand new one, but exact the same issue?.


texts: In our lab we have setup a RS485 network with short cables and the network is working fine.  I know that terminating resistors are required, especially with longer cables lengths due to reflections on the line.  Why do shorter cables work correctly without terminating resistors, and why do we not see a lot more reflections on the shorter line?


texts: Thyristor turn off time in circuit with RL load?

texts:
For circuits like this where the src is turned on, and should turn off in beta as shown in the second image.
What happens when the diode doesnt conduct after pi, when the voltage is negative, will the src turn off when the diode stops conducting ?


texts: Why does capacitance value changes with applied voltage?

texts:
I searched many forums and papers on google and haven't came up with anything. Even asked my teachs and they did not know. One said something about piezo effect but she was not sure about it. So here is a graph by a vendor, change of capacitance value over applied voltage on ceramic capacitor:

Question is simple: Why does a capacitors capacitance with the change of its voltage difference between its polars?


texts:
I have half a meter of 18 AWG (1.02mm diameter) stranded copper wire and I am planning to run 12 volts with a maximum 6 amp load.

Determining the cross sectional area = 0.51mm^2 * PI, gives me ~8.17e-07 meters.

Determining the resistance R = (1.72e-8 * 0.5 meters) / area, gives ~0.0105 Ohms resistance for the half meter length.

My attempt to then determine voltage drop is V = I * R, V = 6 * 0.0105, giving a voltage drop of ~0.063 (~11.94V)

Why then do many online calculators have a multiplier of 2 on this drop? (~11.87V)


texts: How to send (simple) data from GATT client to server?

texts:
I have a PCB which is using a TI Bluetooth LE chip (CC2541). I'm hoping to send some simple weather data from the client (e.g., phone) to the server (CC2541) infrequently (once a day/week). Will a custom profile need to be implemented for this? Could an established profile be modified to handle the data, e.g., the Proximity Profile but with larger attributes?

If every type of data needs a profile, it seems rather clumsy. What is the canonical approach to sending/handling simple data streams?

Thanks


texts: Connecting switch to a resistor in Simulink

texts: This seems to be an easy problem but i cannot figure out how to do it. I have to use switch in my design so that when the voltage across two points excess a fixed amount the switch should be connected to port 1 otherwise port 3. To use that i use control port which is port 2 bu i cannot connect this switch to the rest of the circuit. You can see the design below.


texts: An IC that does sequential counting on a clock pulse

texts:
I want an IC that has 8 outputs, that I can connect to 8 LED's in a circle.  At any point in time one of the LED's is on.  When I press a button, the next one turns on.

I know it can be done with 8 flip flops, but I imagine surely there is a ready-made IC I can just use to save time?

Thanks.


texts: Resistor values for a passive audio mixer?

texts:
I'm trying to come up with a schematic for building a passive audio mixer for an aviation headset, but I'm having some questions about resistor values.  Figuring out the general circuit is easy enough, but I'd like to bounce this off people who know a lot more than I do so I can make sure I'm doing this right.

The idea here is to combine the audio from the aircraft intercom system with the audio from a MP3 player and send it to the low impedance headset (10 ohms).  I'm not that worried about sound quality because the headset itself has a small frequency range (100Hz - 5.5kHz).

Here's what I have for a schematic so far:

My question is, what should I be using for resistors here?  Would 10 ohm resistors be sufficient for this?  I feel like this is pretty basic stuff, but my Google Fu is failing to help me find the answer I need.


texts: Why are high values of capacitance in low pass active filters not recommended?

texts: I am  designing low pass active filter (Sallen-Key structure) and I have come to a point where I have to decide what should be the value of C (C1 = C2 = C) and then calculate values of resistances. I know that capacitance can not be very low because then I would have to take into consideration parasitic capacitances of other elements on the PCB. I also know that it is not recommended to take high value of C but I do not know why.


texts:
I want a cheap tool for investigating the source of and solutions for static electric shocks (from a vehicle).

This link shows a particularly attractive solution; just a FET, LED, resistor and battery.

I have some questions though.

Will it work with both positive versus negative charges? If not, how could it be modified?
How easily can the FET be damaged? Is there any way to protect it?
How could the circuit be modified to give a better idea of the magnitude of the charge? (For the sake of vaguely determining the painfulness of the shock - voltage or amount of charge or both? I don't know). Simply measuring the drain/source current with a multimeter perhaps?

I don't know if it will be more useful to have the device detect charge at a distance, or by contact - perhaps the indication of magnitude would be most useful as it would enable both.


texts:
simulate this circuit – Schematic created using CircuitLab

I have +9v connected via 180 ohm resistor to the collector of an NPN transistor.  The emitter is connected via 680 ohm resistor to the anode of an LED, with the cathode connected to ground.

If I allow a small current to flow into the base, the LED lights up and the voltmeter reads about +2V as I expected.

Here's the thing that doesn't make sense: with the base connected to nothing, I can touch the base with my finger to make the LED glow faintly.  And when I measure the voltage across the LED in this circumstance, I find it reverse biased at -4v with one multimeter and -5v with a second multimeter.
I'd love some one to explain this. Thanks.


texts: Always on lifepo4 power supply - will this circuit work?

texts:
I'm building a music box based on a Raspberry Pi and a HifiBerry AMP2 amp. The amp unit takes 12-24V DC and supplies the Pi with 5V. I want to be able to power the amp/Pi by either a mains adapter (16V DC switching mains adapter), or LiFePO4 batteries built into the music box. I bought this cheap battery management module to experiment with:

The module has these connections: a 5-pin plug for monitoring/protection of the cells, a solder patch labelled C- (charging negative terminal?), a solder patch labelled P- (power out negative terminal?), and a solder patch labelled B- (battery negative terminal?).

The only usage documentation is a diagram on the unit indicating that B- should connect to the negative terminal of the first battery in the series and that P+ and C+ should connect to the positive terminal of the last battery.

So, first, am I right in thinking that this unit would normally charge from C- and C+ and that I should take power from P- and P+?

Second, will my proposed circuit below work as a power supply for my amp/pi, so that when the mains adapter is plugged in power will come from the adapter while allowing the batteries to charge, and when it's not charging the power will come from the batteries?

The terminal blocks in my diagram represent the connectors on the module, the two diodes are 10SQ050 10A 50V Schottky with a specified voltage drop of around 0.5V and J1 is the power connector from the 16v supply.

The reason I'm using the two diodes and supplying power from C- and C+ is so that current won't be flowing through the BMS while the box is connected to the mains. Considering that the BMS will hold the batteries at a constant 3.7V once charged I'm hoping I can just leave the thing plugged in to mains without harm. Is that right?


texts: What is the purpose of higher-resistance resistors in Astable Multivibrator circuit?

texts: The astable multivibrator circuit has two higher-resistance resistors (47k on the pic). What are they there for? Wouldn't it work without? And what is exactly their function? I spent a lot of time trying to figure it out using this interactive visualization but i still don't understand it fully...


texts: I am building my own distortion pedal but every time I connect it to a 9V power source it does not seem to work?

texts: I am trying to build my own distortion pedal. I initially built this on a breadboard and connected it to a 9V power supply and it seemed to work fine when I connected it to my electric guitar. So I decided to solder it to a prototype PCB board. The ground and live wires are connected to a 2.1mm barrel jack and is then plugged into a 9V power wall adapter. But for some reason every time I try to power up the circuit board the live and ground wires between the 2.1mm barrel jack and the circuit begins to smoke and the plastic casing melts. I am unsure of how to fix this problem and I was wondering if anyone had any solutions? I've added the image of the circuit and schematic below


texts:
I have the very annoying problem of not having grounded wall sockets in an old house. Because of this, e.g. my large SMPS has a voltage potential of 115V AC to a ground wire I pull to a radiator. Hardly best practice, I just use it to ground myself before handling ESD sensitive stuff. Now I bought a 'ground spear', and need to know a few things:

What things absolutely must be grounded?
How can I best ensure a long life with regards to weather, contact between the ground spear and wires.
What type of wire should I use? I expect copper will oxidize rapidly once exposed.
How deep should I bury it?
Can I use a system of diodes to prevent voltage from the grounding wire killing my electrical devices? I don't expect this, but I would rather not explain to an insurance agent that my ground wire was played with. Note that I have both DC and AC to ditch from various devices.
And last, but not least stupidly, I want to be certain ground is ground, and that from A (my apartment) to B (the earth), I have continuity. I want to trip a relay instantly if GND is not on the line, so to speak, and alert me with a buzzer. My janitors are morons, and may interfere with my ground wire. It's no use explaining it to them. I'm adept enough to build a sensor - but what should I sense for? And how should I go about filtering out transients and a bit of AC on the wire being sensed upon?

Thanks, you boys are the best. Cluebats at the ready!


texts: Can I change the size of a symbol in EagleCAD?

texts:
I am new to EagleCAD and I just finished generating a new complementary MOSFET in a TSOP-6 package. Everything was fine until I pulled the new component into my schematic and realized that it was way too big in comparison to the other components.

Is there a way to shrink the symbol without having to redraw it from scratch?


texts:
I compiled openocd from git (latest commit: March 7, 2021) with --enable-cmsis-dap.
openocd cannot open my CMSIS-DAP device:
openocd -f interface/cmsis-dap.cfg -f target/max32660.cfg
Open On-Chip Debugger 0.11.0+dev-00056-g6448f70-dirty (2021-03-20-23:58)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Error: unable to find a matching CMSIS-DAP device

Warn : Flash driver of max32xxx.flash does not support free_driver_priv()

USB setup is fine. See, pyocd finds the CMSIS-DAP just fine:
pyocd cmd --target MAX32660
Connected to MAX32660 [Running]: 044400006fed0cc900000000000000000000000097969904
>>>

So how can openocd not find it?
Also, openocd used to be able to find it. How can it change its mind?
Here is more debug output around openocd's interaction with the CMSIS-DAP device:
Debug: 108 14 cmsis_dap_usb_bulk.c:177 cmsis_dap_usb_open(): enumerating interfaces of 0x10c4:0xea60
Debug: 109 15 cmsis_dap_usb_bulk.c:157 cmsis_dap_usb_open(): found product string of 0x0d28:0x0204 'DAPLink CMSIS-DAP'
Debug: 110 15 cmsis_dap_usb_bulk.c:177 cmsis_dap_usb_open(): enumerating interfaces of 0x0d28:0x0204
Debug: 111 15 cmsis_dap_usb_bulk.c:244 cmsis_dap_usb_open(): skipping interface 0, endpoint[0] is not bulk out
Debug: 112 16 cmsis_dap_usb_bulk.c:224 cmsis_dap_usb_open(): found interface 3 string 'CMSIS-DAP'
Debug: 113 16 cmsis_dap_usb_bulk.c:244 cmsis_dap_usb_open(): skipping interface 3, endpoint[0] is not bulk out
Debug: 114 16 cmsis_dap_usb_bulk.c:237 cmsis_dap_usb_open(): skipping interface 1, has only 1 endpoints
Debug: 115 16 cmsis_dap_usb_bulk.c:285 cmsis_dap_usb_open(): skipping interface 2, class 10 subclass 0 protocol 0

Looks to me like it "found" the device? So what is the problem then?
Update: If I unplug and replug the CMSIS-DAP, then it works. But it seems that after running a few commands in pyocd (which generally works better than openocd) then openocd has this problem again. So, kind of a workaround, but painful.


texts:
I'm working on a project where a raspberry pi zero will be the main controller.
The pi has to receive information from a GPS module (gy-gps6mv2) over UART. The same pi will be controlling (receive and transmit) a bare Atmega328 (let's call it an Arduino).

I'd like to stay away from USB. The project has to be compact. This means that I've only got one serial port on GPIO of the pi. I have considered softwareserial on the Arduino, passing the information to the pi, but the Arduino is already doing a lot of work and softwareserial is by no means reliable enough. Bitbanging GPIO pins on the pi to establish serial also doesn't seem like an amazing option.This means that I'll have to come up with another way to communicate with the Arduino.

I know both the pi and the Arduino have I2C and SPI, but there seems to be surprisingly little information out these about pi-arduino communication over any of these 2 protocols. The Arduino is already configured as a I2C master, communication to a barometric sensor (slave) so I assume (?) SPI is the only option left.

What would be the best way to establish this communication? Are there other ways to accomplish this? Does anyone have any experience with this?

EDIT

As some have pointed out, I should've provided more information.

The communication from the gps to the pi happens at baudrate 9600. The pi does not send anything back to the gps. The 2 way pi-Arduino communication has to be at least 9600 as well. There is a constant data stream between the pi and the Arduino, making MUX infeasible. As far as I understand, this also means that making the pi an I2C slave of the Arduino isn't really an option because I2C is needed for the barometer-Arduino communication (I2C is however new to me, my assumptions might not be right). I haven't tried bitbanging/softwareserial, but according to what I'm reading online, this takes a lot of processing power and the losses get up to 10%.


texts:
I am working on ARM & based LPC2468 controller interfacing with USB printer.I have successfully configured a Printer and it is working Properly. Now i came across a new printer Manufactured by Wipro,when i connected it to my device it didn't work.After researching a lot i came to know that my earlier USB printers (TVS, EPSON) use to send their endpoints (in and out)numbers during the setup phase(i.e in endpoint descriptor)but Wipro's printer send 0x00
at the place on in and out endpoints. Is there any way by which i can know or assign endpoints(both in and out) to the Printer.


texts: Can I test if a battery is connected to a circuit?

texts:
I have a 12 V rechargeable lead acid backup battery that is connected to a circuit. When the battery is not in use there is a constant 12 V applied for charging, and when the battery is in use there is still the 12 V at the input pin.

Is there any way of measuring whether the battery is connected, and if it is charging or discharging from the + pin of the battery? This all needs to be put into one circuit so anything bulky will not work.


texts: Newbie: powering and controling a motor - 12v

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This is my first time dabbling in the electronics world and I am currently working on a project for a friends work ute.

I currently am in the planning stage but I found the following motor will be more than adequate for the job at hand (flipping a plate 90 degrees on demand and then back to static position) the plate is about 1kg in total.

Now I have a few questions on this. I am a mechanic so my way of thinking is a little different. With this motor (link below) it is as simple as wiring in a positive and negative wire with a switch? Or will this require some sort of controller with parameters to rotate it to the desired angle and then switch polarity for the opposite rotation? Also this will be set up on a 12v vehicle so will it require an invertor or anything of the sorts?

https://www.robotgear.com.au/Product.aspx/Details/725-131-1-Metal-Gearmotor-37D-x-57L-mm-12V

Sorry for the newbie questions but im very new to this sort and am keen on learning.

Much thanks

Michael


texts: Did I use Diodes and the Relays correctly in my Circuit Design?

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I'm a beginner and recently started a project where I build my own portable bluetooth speakers. I already have a rough layout of the whole thing. I basically want to power a 2x50 Watt Amplifier with two batterypacks wired in parallel.
Now I also want to be able to drive/charge it with a 120W Powersupply, but in a way where I can plug in the Powersupply and flip a switch to disconnect the batteries from the circuit, so the speakers don't draw power from them. If I were to not flip the switch, the powersupply should work as a charger, independent of if the device is on or not. For the Wires going into the Amp I couldn't find a DTDP Switch that could handle 100W-120W of DC Power, so I opted to use 2 Different relays to switch my circuits. I wanted to power them using the Powersupply when its plugged in, since thats the only time I would want to disconnect the batteries/ the battery chargers.

Now my questions are:
1. Did I use the Diodes for the Relays correctly concering the Voltage Spikes that happen when you disconnect them?
2. Are the Diodes going from the Chargers to the batteries even necessary? My orginial thoughts were, since I use the same ports for charging and discharging I could use some Diodes to prevent the current to flow in the wrong direction, into my CC-CN charger. Do these already have protection or was this a good idea?
3. Are the Relays I selected fine for this usage? I will link the datasheets below.
Google Drive download link to the 2 PDF Datasheets
If there are any other glaring mistakes I hope you guys can point them out to. Thanks in advance for the answers!


texts: What are the benefits of a PCB over other methods?

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Besides the obviously poor choice of a breadboard for a product, what benefits are there to a PCB over things like protoboard with wires soldered? Is it just the size and amount of "wiring" that's already done on a PCB, or is there a benefit to the thin conductive lines on a PCB?

To clarify, sorry if I was vague, this is primarily a technical question about the electrical properties of circuits on a PCB compared to other methods but I'd be pleased to read about other criteria that differentiate the PCB from other circuit implementations.

In short, why should I go to the trouble of making a PCB?


texts: I2C read/write failure under heavy interrupt load

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In my system, I am using I2C and I realize under heavy interrupt load (from other sources), I2C communication is easily disrupted. Is this expected behavior for I2C? I would have expected despite interrupt load, it would still be ok since I2C is not exactly a time critical interface, clock is provided with data.

Update:

The processor is STM32. The interrupts are due to ADC, I cannot disable interrupts during the read events therefore I must find a solution where I can make the i2c communication more stable. The STM32 is master and the slave is another device (accelerometer).

Update2:

When I connect a logic analyzer to the clock with a small flying cable, the problem disappears. Interestingly, there is no interrupt load, read write works well, when there is interrupt load, they don't. However, if I attach the probe to the clock, read write works under interrupt load as well. I think, there is a capacitance issue somewhere.