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

swordholder · 10th Jan 2010, 9:30 am

Ed and others,
If you are going to get a transformer wound, may I make a couple of suggestions.
Don't bother with a 250 - 0 - 250 winding, make it a single 250v one and use a bridge rectifier, I could redesign the PCB to include the 2 extra diodes if required.
Include the 30v winding for the LT supply.
Include the 3 x 6.3v windings for the DVMs
It may be worthwhile to have a multi-tapped heater winding to include 4v valves etc.
If you are testing directly heated valves, an extra switch will be required to connect one side of the heater to 0v. This will of course mean that the C/H LED will stay alight unless a second pole on the switch disconnects the LED.
I realise that the cost of a custom wound transformer depends on the number of windings, so it may not be financially viable to replace the LT and DVM transformers.
What do other members think?
Regards to all
Mike

10th Jan 2010, 9:30 am	#44
swordholder Rest in Peace Join Date: Aug 2009 Location: East Preston, Sussex Posts: 162	Re: Homebrew Valve Tester Ed and others, If you are going to get a transformer wound, may I make a couple of suggestions. Don't bother with a 250 - 0 - 250 winding, make it a single 250v one and use a bridge rectifier, I could redesign the PCB to include the 2 extra diodes if required. Include the 30v winding for the LT supply. Include the 3 x 6.3v windings for the DVMs It may be worthwhile to have a multi-tapped heater winding to include 4v valves etc. If you are testing directly heated valves, an extra switch will be required to connect one side of the heater to 0v. This will of course mean that the C/H LED will stay alight unless a second pole on the switch disconnects the LED. I realise that the cost of a custom wound transformer depends on the number of windings, so it may not be financially viable to replace the LT and DVM transformers. What do other members think? Regards to all Mike