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What to connect to center-taps of ethernet magnetics

I'm designing a couple of PCBs to send data and be powered over ethernet, however, I am not entirely sure what to connect to the center-taps. I've heard differing suggestions, from connecting it to ...
0 votes
0 answers
15 views

Can you identify this resistor or resistance?

I was just cheking my batteries and noticed that one doesn't charge. When I opened it, I found that this resistor or a resistance is broken and is not allowing the charge to travel to the battery. I ...
  • 1
0 votes
1 answer
24 views

How much more efficient is 240 V than 120 V?

I've got a PHEV that currently uses a level 1 (120 V) charger, which works fine and can do a full charge overnight. It's fairly trivial to upgrade to a 240 V circuit, but I'd have to buy a level 2 ...
  • 101
-2 votes
0 answers
12 views

Circuit board with power but not responding [closed]

You can see it light up but I got no response when I press the buttons or the remote. I’m clueless so sorry for my dumb questions. What should I do? Replace it? Replace just a cable?
0 votes
1 answer
14 views

Confused with input configuration type of an MCU

Following is an input with pull-up configuration: And below is an input with pull-down configuration: But for this MCU the following register is given as GPIO input options: But this is confusing ...
  • 3,510
0 votes
0 answers
12 views

Connecting LED indicators

I have schematics of system that I design. When SW1 is closed, SW2 is open and the battery getting charged via the Charge Controller with around 6 V and 500 mA. ...
0 votes
1 answer
19 views

Thermo-electric generator (TEG) harvesting using LTC3108

I'm doing a project regarding thermal energy harvesting using TEG and an LTC3108 boost converter. I have constructed the circuit according to the datasheet of the LTC3108. I used a 1:100 surface-mount ...
0 votes
0 answers
13 views

PSU terminal voltage drop when e-load is set in CC mode

I'm using a KIKUSUI PSU and a KIKUSUI electronic load. I'm driving 5 V and 1 A and setting 0.5 A on the e-load to sink, but my terminal voltage is reduced to 3.8 V. Is this drop acceptable?
2 votes
0 answers
20 views

LM386 driving transformer going into oscillation

I have a transformer on the output of a LM386. The circuit works just fine with 42TU003-RC, but when I use any other transformer the circuit goes into osillation at ~350 kHz on the output of the LM386....
2 votes
0 answers
19 views

Is compliance testing necessary for PCIE3.0 if the SOC and Wi-Fi chipset is on the same board?

In my product, PCIe is just used for data transmission between SOC and Wi-Fi chipset. It's not used for any other purpose. Is compliance testing necessary for this scenario? What type of SI ...
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0 votes
0 answers
26 views

Is it possible to modify a commutator to make a DC motor oscillate at 180° without a full 360° turn?

I can understand how a DC motor works, and keeps rotating in the same direction with the split design of the commutator. The following (simplified) picture nicely explains it: From here. I know we ...
0 votes
0 answers
16 views

Model skyworks si3404 DC DC converter in spice from basic diagram (can it be modeled)

I have a DC DC converter that I'd like to model, I am not a super expert in DC DC converter design (never took the class). The manufacturer provides little to none information on using the chip in a ...
  • 65.4k
1 vote
0 answers
20 views

Circuit protection for measuring high-side current using Adafruit INA219

I've been thinking about monitoring the power draw within my solar-based chicken coop setup to get a better understanding of the true power consumption for estimating battery life. I have a 12 V deep ...
  • 117
0 votes
5 answers
52 views

How to connect two separate amps into a single speaker?

I'm building a fm radio/ mp3 player device that is controlled by an arduino. Each module has it's own amp/output to speaker. When I try to connect the output from each device into one speaker by ...
5 votes
1 answer
24 views

How can power factor be reliably estimated given the phase error in current sense transformers?

The majority of mains power sensing devices I've seen (both commercial products and ICs) utilise a current sensing transformer. Many of them also calculate or estimate power factor. However, the phase ...
  • 7,549
0 votes
1 answer
61 views

Can I get this motor to run AC?

My daughter has a project coming up for school. How can we use the turn table motor as a generator to power a shaded pole fan motor?
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0 votes
1 answer
35 views

Circuit Analysis: R3(Missing), Voltage(Missing) [closed]

This is a very simple circuit but I cannot solve it as I'm very slow in circuit analysis. Hence, I'd like to ask if someone can show me how to solve this one.
0 votes
1 answer
42 views

Second opinion: circuit for camping van

I am customizing a van to take on a camping trip and want to install some electrical applications. With only little experience on this topic I did my research online and drew up a schematic for the ...
-2 votes
0 answers
51 views

Build a portable scanner [closed]

I'm looking for a component for building a scanner similiar to any of the book scanners like irisscan, ut with the ability to send the scanned image in realtime similiar to an ordinary webcam. ...
  • 115
0 votes
0 answers
25 views

The routing delay is 0 ns in quartus chipplanner

I designed a program about TDC. However, I found the routing delay is 0 ns when I check its timming by Timequest. Shown below, the Tco is 0.073 ns, but the routing delay is 0 ns. Obviously, there is ...
  • 1
0 votes
3 answers
66 views

Does collector feedback bias work like this in real life?

I am reading about collector feedback biasing in BJT transistors. Here is how it works: Now suppose for some reason, a temperature change perhaps, β increases. This should cause an increase in IC. ...
  • 101
0 votes
2 answers
54 views

How to make the microcontroller respond/compare I2C data faster in this case?

I measure the current via an I2C current sensor by using this STM32F302 Nucleo board. And I display internal temperature and the averaged current value in an OLED display. But I do everything in ...
  • 1,303
0 votes
0 answers
13 views

Show that specific functions are correct for a race free Moore-machine?

So we have a state transition graph in Moore-form. The inputs are in the form of $$(x_1, x_2)$$ The output are the names of the state (Moore) and are named as $$(f_1, f_2)$$ and updated outputs $$({f^...
0 votes
2 answers
63 views

What is the best technique to find out which diode is conducting and which diode is cut-off in the circuit?

What is the best technique to find out which diode is conducting and which diode is cut-off in circuits below?
  • 115
0 votes
2 answers
60 views

Guitar amplifier emits a continuous beep, which pitch vary depending on "bass" and "gain" knobs. Finding what's wrong in the circuit

I have an old transistor (EDIT: not transistor, but OP, from comments) guitar amp, a Laney Session 45 Reverb. I couldn't find any schematics online unfortunately, it doesn't seem to be a very popular ...
  • 101
0 votes
0 answers
16 views

Programming with AVRDUDESS without response

I am trying to program an ATmega64 which has a bootloader on it but the RS485 transceiver has been designed with the D, !RE, and Tx pins shorted to GND so it can never respond. AVRDUDESS never ...
  • 1
0 votes
0 answers
44 views

Step down 100V to 26V with some specific requirements

I'm trying to repair an HP 8555A spectrum analyzer module which shows problems in the step-down power module. I'd like to replace the module which steps down the 100V coming from the mainframe unit to ...
-5 votes
0 answers
46 views

What are the automated tests for PCBs and complex electro-mechanical subassemblies? [closed]

Developing and improving test procedures for PCBs and electro-mechanical subassemblies to ensure functional requirements are satisfied
  • 73
2 votes
0 answers
17 views

What is the relation between filter coefficient (N) of Simulink pid block and filter time constant of MATLAB pid command?

What is the relation between filter coefficient (N) of Simulink pid block and filter time constant of MATLAB pid command? According to my experience they are not same or equal, there is some other ...
  • 791
0 votes
3 answers
63 views

How to figure out the direction of current and polarity of a circuit element?

How do I determine the direction of current in the boxed region? Also, how do I figure out the polarity of the resistor?
-5 votes
0 answers
45 views

Operation, maintenance and development of electrical and electronic hardware in a user facility [closed]

What is the context meaning? I really do not understand.
  • 73
3 votes
3 answers
248 views

What is the etymology of 'plane' e.g. data plane, control plane, etc.?

My guess would be aviation (used as an analogy), but I find no source for this. Data plane was being used as early as 1965 (e.g. in this paper) https://ieeexplore.ieee.org/abstract/document/4038491 &...
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0 votes
0 answers
29 views

Motor inertia estimation

I am trying to design a self-tuning PID controller to control the BLDC motor speed loop. The plan is to use a look-up table to adjust the PID coefficients depending on the motor load inertia, but I am ...
  • 61
0 votes
0 answers
24 views

9 V supplied to 12 V piano [closed]

I used 9 V to power my 12 V piano. It worked for a while, but after a week my piano wouldn't turn on anymore. Is my piano already damaged? Or will it be normal again if I power it on at 12 V?
  • 1
3 votes
2 answers
217 views

When the RS232 call is canceled, which pin transmits it to the DTE?

According to my research: When the call to DCE in the RS232 protocol arrives at the ring indicator (9) pin is activated and information is sent to the DTE. Let's say we talked for a while and we had ...
0 votes
0 answers
7 views

How to convert LVDS to LP-HCSL (no internal bias at the receiver)

I want to interface LVDS clk output (PCIE Sw) to LPHCSL (clk buffer) and the convert LPHCSL output to LVDS(End Points).
  • 13
0 votes
0 answers
28 views

How to connect an EC11E rotary encoder to a microcontroller?

I'm connecting a EC11E rotary encoder to a Adafruit Feather 32u4 Bluefruit LE. The EC11 has 5 pins: 2 for the switch, and 2 for the knob. Connecting the encoder itself would be easy, but I'm having a ...
  • 101
0 votes
1 answer
45 views

Why do electronics and live wires cause a buzzing in my headphones

I have a pair of wired over the ear headphones with a normal headphone jack. I noticed a few days ago that if I went near wires that are plugged in or got close to electronics it would make a buzzing ...
-3 votes
0 answers
42 views

Can I connect a new circuit in parallel to the existing car charging light indicator?

Here is how the LED is ON and OFF. The led represents the BATTERY CHARGING LIGHT on a car. It has constant 12V and is a ground side switch. Whenever Key is ON, it STAYS ON. As soon as engine is ...
  • 49
3 votes
4 answers
261 views

Is an op-amp's output current limited by the supply (+/- Vsupply)?

As above. I'm looking at the OPA548. The max. output current is 3 A, but reading the datasheet, I'm unsure if that's from the +/- Vin or the +/- Vsupply.
0 votes
3 answers
86 views

Why aren't there displays which explicitly emit certain frequencies?

Rather than building displays that emit RGB, why not build displays that emit certain frequencies instead? What are the technical challenges of doing this?
-2 votes
0 answers
37 views

Intel Core i5-1240P vs Intel Core i7-1165G7 [closed]

Refer: Intel Core i5-1240P vs Intel Core i7-1165G7 As I see that Intel Core i5-1240P outsmarts Intel Core i7-1165G7 in most of the benchmarks as shown in the above link. Can I conclude that it is ...
3 votes
1 answer
205 views

What is the definition of phase margin?

From wiki we could see the definition of Phase Margin: In electronic amplifiers, the phase margin (PM) is the difference between the phase lag φ (< 0) and -180°, for an amplifier's output signal (...
  • 199
0 votes
0 answers
40 views

Submerged water pumps (sump pumps, pond pumps) - risks

I always wondered about the safety of submerged water pumps, like pond pumps and sump pumps. Electricity and water do not mix. Sump pumps for reliability are installed on non-GFCI outlets. What ...
1 vote
1 answer
47 views

MOSFET push-pull low current problem

I am trying to make a push-pull amp to drive a dc motor with a dual power supply. I have this circuit and it works but I can only get about 1A of current for each rail. Is it possible to raise this ...
  • 621
2 votes
2 answers
52 views

Phasor of transfer function

Say I have the following transfer function: $$\mathcal{H}(s) = \frac{Bs^2}{a^2 + \frac{a}{Q}s +s^2}$$ I want to prove it is a Low-Pass filter. In order to do it I'd like to change it to phasor form so ...
  • 551
5 votes
2 answers
357 views

Response of diode circuit

I am a bit confused by the response of this circuit given the input. For the positive part of the circle, the diode is reverse biased. As such, the circuit becomes 3 kΩ in series, with a 7 kΩ sticking ...
3 votes
1 answer
109 views

Why does this MOSFET not switch 9 V?

I am designing a circuit so that I can mute/unmute a microphone using an Arduino/Raspberry Pi. I am using a CD4051 which is designed for controlling audio applications. The schematic is based off of ...
  • 311
0 votes
0 answers
38 views

Identifying 6-pin SMD with 04K marking

There is an SMD component on this PCB that I think is a 6-pin SOT363, and the marking is 04K. Does anyone know what this component is?
0 votes
1 answer
50 views

Where do I attach the ground wire from a 3.5mm audio cable?

I have a 3.5mm audio cable coming from a raspberry pi with wires exposed at the other end. I've soldered the positive and negative wires to the inputs of an amplifier board that I bought on eBay. ...
  • 101

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