UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

kalee20 · 14th Sep 2018, 1:20 pm

If using a Variac, it's definitely worthwhile putting a fuse in series with the OUTPUT!

Driving a faulty, short circuited load, only a few volts will cause umpteen amps to flow, enough to burn out the Variac brush (and maybe a current meter and wiring, as you have found), while still drawing only 100mA or so from the mains, thanks to transformer action.

14th Sep 2018, 1:20 pm	#4
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,081	Re: Lamp limiter plus Variac tip If using a Variac, it's definitely worthwhile putting a fuse in series with the OUTPUT! Driving a faulty, short circuited load, only a few volts will cause umpteen amps to flow, enough to burn out the Variac brush (and maybe a current meter and wiring, as you have found), while still drawing only 100mA or so from the mains, thanks to transformer action.