Electrical Engineering Weekly Newsletter
Electrical Engineering Weekly Newsletter

Top new questions this week:

What makes mains voltage safe in homes?

When I started learning about electrical engineering, one of the most important safety guidelines that I learned was that voltages over 36V can be dangerous. As my circuits professor put it, 120VAC …

voltage ac safety mains  
asked by Kynit 8 votes
answered by Andy aka 18 votes

PCB's and designing power connections

I've designed a few PCB's now, but never put much thought into good practices. They were small boards and most of the emphasis was put into just making sure everything that needed to be connected was …

power pcb-design ground pcb-layers  
asked by bwoogie 7 votes
answered by gbulmer 5 votes

Is a two-element circuit series or parallel?

Is the voltage source in series with the resistor or is the voltage source in parallel with the resistor? If the voltage source is in parallel with the resistor, then why do they share the same …

circuit parallel series  
asked by user53172 5 votes
answered by avngr 7 votes

How to drive 128 LEDs

I now have a PCB with 64 UV LEDs on it and I use this to expose other PCBs. I have a serial resistor for each LED which produces a lot of heat and consumes about 1.3 A at 12 V. I am now considering …

asked by maikel 5 votes
answered by Ale 8 votes

Is this a correct way to have a 1 second delay?

If I have a PIC24 with a 4 MHz frequency. Is it accurate to have a 1 second delay by having 4 million clock cycles? I made a 1 second delay like this on my PIC24FJ128GA010: MOV #244, W3 DL: …

pic frequency assembly delay  
asked by 3bdalla 5 votes
answered by Majenko 7 votes

Reverse Engineer Serial Signal

This is a long post as I want to take you through all the work I've done. The TL;DR version is I've got an unknown controller for a mechanical heat pump and I'm trying to reverse engineer the signal …

serial reverse-engineering serial-bus saleae-logic-analyzer  
asked by user3180989 4 votes
answered by MarkU 2 votes

GLONASS and GPS satellite usage simultaneously by Positioning Modules

Can a GPS module use 2 GPS satellites and 2 GLONASS satellites to obtain a fix without using all satellites of the same kind? I know that we cannot force this to happen but is it theoretically …

gps navigation  
asked by QwertyCoolGuy 4 votes
answered by one.tobi 5 votes

Greatest hits from previous weeks:

Does mAh measure how long a battery would last?

I know mAh tells how much milliamperes a battery can deliver in an hour. But does that also tell how many hours the battery would last? Sorry but I don't really get it. If we're talking about a water …

asked by supertonsky 23 votes
answered by Phil Frost 34 votes

Decoupling caps, PCB layout

I guess I've been somewhat ignorant when it comes to the finer details of pcb layout. Lately I've read a couple of books that try their best to lead me on the straight and narrow. Here is a couple of …

pcb layout decoupling-capacitor  
asked by morten 79 votes
answered by Olin Lathrop 155 votes

Can you answer these?

Finding the Thevenin Equivalent Resistance

In this problem I'm trying to find the Thevenin resistance in the circuit below: simulate this circuit – Schematic created using CircuitLab The first thing we do is remove all sources …

circuit-analysis thevenin  
asked by Lefty 1 vote

Capacitive where is the touch?

I am a newbie in the world of circuits and electronics. But we all started somewhere. I have this idea about a street sign that should be used as an instrument. All most like a Theremin. Touching it …

sensor raspberry-pi capacitive  
asked by Bjørn ChrisB Christiansen 1 vote

A (touch) screen technology to identify several input devices

This may sound vague, since I am not sure if what I am looking for even exists, but please bear with me. I am interested in a technology that would allow me to not only locate, but also identify …

sensor touchscreen capsense  
asked by ernes7a 1 vote
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