Bench Bulb Limiter

An adjunct to my bench variac - a current limiter with three ranges.

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Once I completed my bench variac, I wanted to add a bulb limiter to the bench. These are not complicated, and the simplest limiter can be made for about $10. But, as it was going to be a part of the bench, I wanted something a step up.

This limiter has it's own on/off switch, a (covered) switch which allows the bulbs to be bypassed completely, and switches for each of the bulbs. With both a 150W and a 300W bulb, I can limit to 1.25A, 2.50A, and 3.75A. If need be, I can of course use lower wattage bulbs for greater current limiting (a 45W bulb would limit to 375mA.)

The plug in RV volt meter (85V - 300V) is from Amazon, and shows the voltage drop due to limiting.

The limiter is connected after the variac, which is after an isolation transformer, rounding out the isolated AC available on the bench.

You can check out my video about the setup here:

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