Sunday, December 11, 2022

Lightbulb Limiter


I got the big amp repaired and it was time to try it out. The amp has some serious high-voltage circuits in it and I didn't want anything to go wrong and blow up, so I built a "lightbulb limiter". It's a box that puts an incandescent lightbulb in series with an outlet. As long as whatever is plugged in doesn't draw a lot of current, the lightbulb stays dim and there's voltage to the plug. As soon as the current goes up (something went wrong), the bulb lights up, its resistance goes up, and the current is limited.


The high voltage circuit runs at 460 volts DC. It was daunting to be probing around with that sort of voltage present. I kept one hand in my pocket the whole time. Everything checked out and the tubes are now glowing and amplifying music like they should. 100 Watts of tube amp is more than anyone needs in their garage. It's like having a 4,000 horsepower engine in your car.


 

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