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
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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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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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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