Just make sure that these step-down trannies are not autoformers! In Brazil they love these to handle 220V - 110V and vice-versa. You can test it by checking for continuity (resistance) between 'primary' and 'secondary': if you can measure a resistance it means it is an autoformer, and your 'secondary' is actually connected to the net!
Nope leadbelly. Sorry just lack of time, in between work, looking after a 4 month old baby and trying to do some soldering whenever I'm not changing nappies or heating up formula!.
For sure. These step downs are truly big EI transformers. Aournd 25 uSD for a 400Watt model increasing to around 60 USD for a 1000 watt model.
Was post #6 not suitable?
http://www.diyaudio.com/forums/tubes-valves/172894-voltage-doubler-using-psuii.html#post2290256
Sorry leadbelly, I was just trying to be of help; it is not my thread and I don't think any of my points were utterly stupid or if they were they were not unthoughtful.
No need to apologize, I was just trying to make a point about how invaluable searching the forum can be.
sorry missed that one. was multitasking at work😛
don't we need a resistor/cap series and also change the load to constant current?
How does this look? 723 mV of ripple. maybe with another series of caps this can lower. maybe 2 series of 10000 instead of 1 of 20000uF.
I get 110 volts with this. Perfect for the 6080's.
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Well hooked it all up to 2 x 6080 in parallel.
After plate resistor got a nice 116v and 100mA bias
BUT a horrible humming from the power supply😡😡
Got 20,000 uF on the last series of caps.
Too much ripple? Not enough filtering?
Maybe some more series of caps.
Maybe just a new transformer will be cheaper than all the big caps😛
After plate resistor got a nice 116v and 100mA bias
BUT a horrible humming from the power supply😡😡
Got 20,000 uF on the last series of caps.
Too much ripple? Not enough filtering?
Maybe some more series of caps.
Maybe just a new transformer will be cheaper than all the big caps😛
I think I should have the highest capacitance on the first leg of caps.
you can see I get much lower ripple with 20K (39mV) on the first leg rather than the last (738mV). Maybe a CCS on the anode would filter out some noise but at 1 amp my DN2540's would explode. I'll try tweaking the caps tonight.
you can see I get much lower ripple with 20K (39mV) on the first leg rather than the last (738mV). Maybe a CCS on the anode would filter out some noise but at 1 amp my DN2540's would explode. I'll try tweaking the caps tonight.
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Tried adding more caps but to no avail. Even tried a SRPP circuit with a cascode DN2540 on the plate but still a nice humming sound.
This voltage doubler with 2 trannies in series hasn't worked for me this time.
🙄
This voltage doubler with 2 trannies in series hasn't worked for me this time.
🙄
Maybe it's not ripple then. Maybe its a bad ground scheme, magnetic fields, or just buzzing transformers!
I'll try the other circuits mentioned on the other thread and also just 1 tranny instead of 2 in series. If no success I'll keep these trannies for heater supplies then.
They are good to heat 4 x 6.3v valves in series and with 3 amps, I can run 4 x 6as7/6080 easily. Hardly got warm.
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well I tried the 1 tranny doubler and als a quadrupler by valve heaven, with different layouts and existing amps that are quiet and can't get the doublers/quadruplers to stop humming.
Maybe it is the trannies I bought.
Maybe it is the trannies I bought.
In any power supply using just transformers, diodes and capacitors, if there is excessive hum, I would always suspect the capacitors first. Your problems in achieving practical DC output voltages close to the theoretical values could also be caused by faulty capacitors.
Other possible sources of hum are those mentioned in MerlinB's post.
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