[SOLVED] Voltage doubler with voltage regulator

[aurelien_7]

hi!
I need 18 volts supply, since i'm having 12 volts transformer i decided to use full wave voltage doubler to raise voltage to 24 volts.
But at the output of doubler i'm getting 36 volts :/ and after pluging it to LM7818 at the output of regulator i'm getting 3.5 volts
In datasheet of LM7818 maximum input voltage is 33 volts!
So i don't know beacause of the fact that input voltage is exceeding maximum input voltage rated by datasheet I am wierd output from regulator.
So I am open for advices

 

[BradtheRad]

C2 and C3 appear to be only 220 nF. They need to be a much larger value (probably 100 uF or more). That should bring up the output to a higher volt level.

 

[tpetar]

What you say on this circuit :



**broken link removed**

Dont expect to much current from your design, and BradtheRad is right you need bigger capacitors.

:wink:

 

[aurelien_7]

woooho!
i replaced capacitor and instantly the output raised to 18 V!
tnx!