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Old 18th Oct 2019, 9:16 am   #14
allan
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Join Date: Oct 2005
Location: South coast near Ringwood/Christchurch, Dorset, UK.
Posts: 230
Default Re: DIY battery eliminator for valve radio

I think we've moved on a bit since that type of series pass transistor circuit. The newer FETs or IGBTs don't need any power to drive their regulator input.
http://www.radiomuseum.co.uk/power%20supply.html
The IGBT is much like a triode valve in not requiring any grid power for its gate although old radios of course are designed to draw only a small amount of current to keep their HT battery life respectable so one could say that's not as important as say an HT PSU for a transmitter.
For LT, I'm an advocate of the LT1083 (from China) but for only low currents a 317T is readily available.

I didn't find any cheap 240v to 110v transformers for my recent project so I used a salvaged 3xlow voltage type and a voltage doubler which costs next to nothing. I've also used a pair of cheap 240v (120-0-120) split primary transformers back to back in the past. As you might have guessed I hate spending money.
Over the last 25 years as a repairer I've accumulated about a ton of scrap equipment so my junk box comprises 3 large sheds plus the loft above my workshop!
Allan G3PIY
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