Electrical Engineering Stack Exchange Community Digest

Top new questions this week:

What is this chip, who makes it and what's it used for?

I was cleaning out some junk when I encountered an interesting chip. It looks like a remnant from the Apollo space program with its all-metal body with the marking ADC581B 8533 6686. Next to the 8533, ...

integrated-circuit identification  
asked by user148298 19 votes
answered by GT Electronics 40 votes

Scam? Does having this capacitor wired as shown provide any surge protection?

Bought this on Amazon as a dryer 240V SPD. I was trying to find out if this device is an outright scam. I found a similar post on here from several years ago but that did not answer my question. ...

power-supply power capacitor protection mov  
asked by Jason P 17 votes
answered by jwh20 35 votes

How did people make oscillators before they had the triode?

I found on Wikipedia that: “In 1901, Reginald Fessenden demonstrated a direct-conversion heterodyne receiver or beat receiver as a method of making continuous wave radiotelegraphy signals audible. ...

vacuum-tube history  
asked by Camion 14 votes
answered by Jonathan S. 15 votes

Why is the energy in a battery QV, but the energy in a capacitor QV/2

If I know the total charge in a battery, let's say 5000 Ah, and I want to find how much energy is stored in the battery, I multiply the total charge by the voltage E = Q·V; for example, for 12 V I ...

capacitor batteries energy charge  
asked by bibo999999 10 votes
answered by Sandro 17 votes

Pull-up and pull-down resistor on one trace

Does it ever make sense to have both a pull-up and a pull-down resistor on the same trace? Background: I'm designing a backplane to follow the OpenVPX guidelines and I saw this rule Rule 7-20: The ...

pcb-design pullup pulldown  
asked by Q-Tip 9 votes
answered by vir 11 votes

How can the same radio signal be received by 100s of receivers without any loss in it?

In power supply, each house connected to the grid consumes a certain amount of power which leaves less power to be consumed for the rest of the houses. Similar to that, when a radio station broadcasts ...

power rf communication radio  
asked by elliot 9 votes
answered by TimWescott 19 votes

Analog Design of a Miller OTA: Am I doing it right?

So I am doing a class on Analog Design. I have to design a two-stage Miller OTA. I would like to have some feedback about my design procedure and also some help because I am stuck. My professor doesn'...

circuit-design ota  
asked by Granger Obliviate 7 votes
answered by pat 4 votes

Greatest hits from previous weeks:

What is the voltage range of a standard headphone jack from a phone?

I want to connect the output from the audio jack of an iPhone to an Arduino. What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the ...

arduino audio voltage-measurement iphone  
asked by manuelBetancurt 59 votes
answered by PkP 31 votes

Saving Arduino sensor data to a text file

How can I save data retrieved from a sensor to a text file on the computer?

asked by desNotes 37 votes
answered by Nikolaus Gradwohl 31 votes

Open and Short Circuit questions

I am confused on the terms Open, Short, and Closed when talking about circuits. As far as I know: a) Open circuit means the wires are cut off so there will be no current flow, but there is voltage. b)...

voltage current circuit-analysis  
asked by nicy12 7 votes
answered by helloworld922 10 votes

How to change rotation direction of 3-phase electrical machines?

I was taught that if you want to change the direction of a three phase rotating machine that is rotating in forward direction, you interchange the phases. Since the phases has the same features (...

motor three-phase  
asked by Ezeatum Solomon 2 votes
answered by Andy aka 14 votes

What is the purpose of carbon brushes in an electric motor

I just took apart our washing machine to replace the carbon brushes. Was wondering why the machine stopped working when the brushes were worn down? Also if the engine makes a wuring noise after you ...

asked by Shiraz Bhaiji 9 votes
answered by Majenko 11 votes

How to build a 4 to 16 decoder using ONLY TWO 2 to 4 decoders?

Help please, I am new to circuits and decoders and I need some serious help. How to build a 4x16 decoder using ONLY two 2x4 decoders? Following the steps we took in the lecture, we are supposed to ...

digital-logic integrated-circuit decoder  
asked by dondon93 1 vote
answered by Dilip Sarwate 4 votes

Why was Mini USB deprecated in favor of Micro USB?

Mini USB connectors were standardized as part of USB 2.0 in 2000. In 2007, the USB Implemeters Forum standardized Micro USB connectors, deprecating Mini USB connectors four months later. Why? What ...

usb connector standard  
asked by Dan Fabulich 219 votes
answered by Russell McMahon 223 votes

Can you answer these questions?

Program MCU from another MCU

Can I use an ESP32 to program/flash an nRF51822 directly without a PC connected to the nRF? I am designing a VERY small device with two microcontrollers on the same PCB, and would like to save space ...

microcontroller programming esp32 nrf51822  
asked by JohnL 1 vote

Relative error of power estimation

I'm reading my teacher code for FFT windowing in Matlab and there is one thing I don't understand. When you run the code at the end it says: ...

power signal frequency matlab dsp  
asked by mo2323 1 vote

MOSFET N-Channel - RCD051N20

I have designed this circuit that outputs 7 or 28 mA depending is the MOSFET is closed or open. The gate of the MOSFET is controlled with an Analog Output from a DAQ that jumps between 0 and 10V. ...

asked by Jonw3 1 vote
answered by bobflux 0 votes
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