Okay guys, I think I have a tranny that will work perfectly if I can just figure out what the HT voltage is. But I don't have the tranny specs, just a schematic of the circuit it came out of that I will attach here for you all to see. The filaments are shown as + and - 12V. But thats after going through some IN4004 diodes and pretty hefty resistors and caps.
How can i get these to 6.3 Volts? or, are they that already? Not certain.
All other voltages look manageable. At first I thought I'd just go ahead and wire it up for 12V...but that makes no sense because I'm not going to put in that old circuit's diodes and resistors/caps ans stuff. So can anyone calculate what those filaments actually are voltage wise? I'm just not that good with OHMS law and math - please help as I'm so close to getting this circuit to the testing phase.
Help with Liver pool
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Help with Liver pool
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Re: Help with Liver pool
Also - I have only two IN 4007's on hand, but also 4 IN4005's. Could I use the 4007's with the 4005's and get aways with it? Can you even intermix diodes like that? If not, can I just use all IN 4005's? I think they are rated to 600V.
Re: Help with Liver pool
I did find out that this is a 50 watt tranny too
Re: Help with Liver pool
You're going to need to connect the primary's to 115V and measure the secondaries. I'd say it's probably around a 500V transformer so you'll need to drop some B+ to use with a Trainwreck. Post the voltages once you've measured the secondaries and we'll see if it is suitable for a Trainwreck.
As for 12V filament. You can use this on 12AX7 by connecting to pins 4 and 5. Instead of 4/5 and 9, you use 4 and 5 and leave 9 unconnected.
For the output tubes, you could run the EL84s in series. You would wire up two EL84's in series and connect those across the heater so that each tube sees 6V according to Kirchoffs law.
As for 12V filament. You can use this on 12AX7 by connecting to pins 4 and 5. Instead of 4/5 and 9, you use 4 and 5 and leave 9 unconnected.
For the output tubes, you could run the EL84s in series. You would wire up two EL84's in series and connect those across the heater so that each tube sees 6V according to Kirchoffs law.
Re: Help with Liver pool
Yeah - but it's not that simple because those filaments start out life at 25V not 12. It's been suggested that I get new appropriate iron from mosse. Guess that's what I'll have to do. Any ideas what this crazy SD PT might work for project wise?
Re: Help with Liver pool
Whatever you use it for, you could use an LM317 to adjust down to 6.3V and make a nice regulated DC supply.
Re: Help with Liver pool
Hate to show my total ignorance but what an LM317
Re: Help with Liver pool
also - could I just use a little 117x 6.3 volt tranny to run the HT's?
How would I wire that up? Just splice it into the power cord and ground?
How would I wire that up? Just splice it into the power cord and ground?
Re: Help with Liver pool
Oh I get it... a voltage regulator!
Doesn't it take all sorts of calculations to figure what resistors to palce on either side to get to value?
Doesn't it take all sorts of calculations to figure what resistors to palce on either side to get to value?
Re: Help with Liver pool
The wiring would be a pain but you could treat the centre-tapped filament winding as 2x 12V windings and use one half for 2 EL84s in series and 2 12AX7s wired for 12.6V, and the other half for the other 2 EL84s in series and the remaining 12AX7 wired for 12.6V.
This would mean that you'd have to tie the centre-tap to ground rather than the centre of each filament winding, so it wouldn't be as quiet, and you'd also need more wiring to accomplish this.
You could use the voltage regulator method but you need to make sure that the winding can supply the full current at the 24V as you need at 6.3V since the voltage drop times the current drawn will be dissipated as heat by the regulator.
I'd probably just spring for the correct transformer in this case, and speak to Moose.
This would mean that you'd have to tie the centre-tap to ground rather than the centre of each filament winding, so it wouldn't be as quiet, and you'd also need more wiring to accomplish this.
You could use the voltage regulator method but you need to make sure that the winding can supply the full current at the 24V as you need at 6.3V since the voltage drop times the current drawn will be dissipated as heat by the regulator.
I'd probably just spring for the correct transformer in this case, and speak to Moose.