this post was submitted on 18 Jun 2023
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How to properly size a serial bulb for protection when troubleshooting a circuit? (discuss.tchncs.de)
submitted 2 years ago by LemmyBr785@discuss.tchncs.de to c/askelectronics@discuss.tchncs.de
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Hello. I'm a hobbist on electronics repairs, and I did some repairs on stuff powered from the wall socket before, using a serial bulb to protect the circuit in case there's a short. Now I want to troubleshoot a board that works at 3V and very low current (like no more than 100mA). So, how can I properly size the bulb I need for this circuit before powering it? Or is there a better way to protect the circuit than a serial bulb? Thanks in advance.

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[โ€“] jjagaimo@lemmy.one 1 points 2 years ago (1 children)

Ah. It's not going to be possible to size it because the bulb is then acting as a resistor essentially. Unless you know what the equivalent resistance of the circuit you're testing is, and it draws a fixed current, you aren't going to be able to cap the current; Adding a resistor (or bulb) is just going to drop the input voltage and you will probably end up having other issues

[โ€“] LemmyBr785@discuss.tchncs.de 1 points 2 years ago

Ah got it. Then a bench power supply is the way to go. Thanks again!