How can i obtain 24V/100mA (for an EHX Memory Man) from 9V AC?

[gigimarga]

Hello,

I want to modify my power supply and i need to obtain 24V/100mA from 9V AC (at 200mA, if i remember well, so it's ok).

How can i do this in an easy way?

Thx a lot!

[sean k]

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

http://www.kronjaeger.com/hv/hv/src/mul/

The villard and its ability to be cascaded is the one I remember... and like!

I suppose it depends on whether the 9VAC is a peak to peak or a RMS. If it's RMS you should have no trouble getting 24 VDC but if its peak to peak the you'll only get 17.8 or so. RMS would give you 25.4 - 1.2 which is 24.2 so you'll be right on the monkey but I think you might be pushing your 200mA supply for a constant 100mA. Check it for heat once everything is up and running. You can usually push transformer by 10 - 20 percent as long as its a peak draw and not constant.

[theehman]

Reissue or vintage unit?
Where's the 9VAC coming from?

[gigimarga]

@sean k: Thx a lot! Isn't necessary to regulate the tensoin using a 7824 after the Villard? The voltage of 9V AC is measured putting a DMM on the wires of the transformer 

@theehman: i think that the unit is vintage (comparing it with one that i saw on www.musiciansfriend.com)...the 9V AC is one of the twelve outputs of a toroidal transformer from 220V.

[calpolyengineer]

The DMM is setup to read RMS voltage (the expensive ones do real RMS, the cheap ones just divide peak by sqrt(2)). So you should be able to get enough voltage from just a doubler. The current is a little trickier, you would be right on the edge. I don't imagine that you would need a constant 100mA so it would probably be fine. It would be nice to use a regulator, but you need to feed it extra voltage, typically a couple volts.

-Joe

[gigimarga]

@sean k: After reading about the Villard voltage doubler I still don't know which are the values of the capacitors...