# All Questions

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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 ...
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
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
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?
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
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. ...
• 203
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 ...
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?
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....
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 ...
• 29
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 ...
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
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
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 ...
• 103
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
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?
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.
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 ...
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
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 ...
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
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
13 views

• 551
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 ...
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
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?