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Light bulb is series with unit under test

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001:
Hi

I see few recommendation about testing gear with Light bulb in series with line AC voltage
But nobody can tell what about power and voltage of theese "safety" lamps
Do You use this method?

sokoloff:
For low expected current devices, this is good short circuit protection. (If dead shorted, you have. A chance to troubleshoot without blowing fuses.)

Standard (incandescent!!) light bulbs work fine. I use 60W, because that’s the most common type I have on hand. You can parallel multiples if you need 500mA or more of typical current.

Paul Rose:
Use incandescent bulb with voltage rating same as mains.  This will act as a crude current limit for your device.   Bulb wattage depends on how much power you expect your device to draw.

Worst case, the bulb lights up full brightness, the current is limited to the normal bulb current, and the device does not smoke or catch fire.

If the wattage of the bulb is too high, you don't protect as much.  Start smaller (you won't damage the bulb).

The thinking is, if the bulb lights up bright, your test piece was drawing too much.  Unplug, investigate and fix.

I usually see this in guides on repairing old vacuum tube radios.   

001:

--- Quote from: sokoloff on February 04, 2019, 02:50:25 pm --- You can parallel multiples if you need 500mA or more of typical current.

--- End quote ---

Sorry
Can You tell why I need more current if unit failed test?

Ian.M:
http://www.repairfaq.org/sam/tshoot.htm#tshslt

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