Voltage doubler/tripler circuits

[diablo]

After a gap of about 25 years, I'm about to re-start on some DIY amp building.
As part of reminding myself what this is all about, I've ordered a couple of 'class T' kits to practice my soldering on. Also deecided on the power supplies to go with them (well nearly). Must dig out my dusty old theory books and re-learn Thevenin's theorem and the rest.

A longer term aim is to build a four channel amp which is a mixture of designs I've come across. Essentially it will be similar to to the JTLI amp but with a different valve section which requires higher voltages.

I would prefer to use only 3 transformers, for space reasons. I obviously need a separate trans for the valve heaters. But can I use a transformer for each pair of the power section of the amps (+35/-35) which will also supply +70/-70 or even +105/-105 to power the valve stages by using some form of voltage multiplier.

I cannot find too much on this subject by internet search (maybe I'm searcing for the wrong terms?)

Are there any ICs which perform this function?

I'm still in the early stages of designing this, but it would be good if I knew that putting these voltages into a spice program was valid.

How much better will it be to use separate transormers for these stages?

Many thanks or any help.

 

[jan.didden]

Google "voltage doubler". First hit.

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/voldoub.html

Where did you look??

Be aware though that voltage doublers and triplers have generally quite large output impedance. Therefore, if you take current from them, they will quickly sag. But for just a few mA for a tube pre stage it will work.

Jan Didden

 

[diablo]

That's not what comes up when I do a search for "voltage doubler in Google! What gives here?

High output impedance, eh? Will work but may sag? That doesn't sound good.

Thanks for the warning, I think I'll have change the design to find room for two more transformers.

Regards,
diablo

 

[jan.didden]

[snip]Thanks for the warning, I think I'll have change the design to find room for two more transformers.

Regards,
diablo

... or a transformer with several secondaries?


Jan Didden

 

[peranders]

.... the voltage doubler is a hard load for the transformer and also the caps, not so effecient in other words. It's much better with the right voltage from the transformer.

 

[diablo]

Thanks for the replies.

It does make a lot of sense to get custom wound transformers, provided it isn't too expensive. I'll perhaps get a quote or two.

Regards
diablo

 

[TonyTecson]

the voltage doubler is a hard load for the transformer and also the caps, not so effecient in other words. It's much better with the right voltage from the transformer.

for ss amps, yes, for tubes where load currents are in milli Amps, voltage doublers are very attractive! low voltage transformers can be used, example, a 150vac sec gives you 400+ dc easily!

myself uses voltage doublers for tubes!