[guzzler]

I've just enclosed a 15-0-15 transformer wired in series to give a nominal 30V output... however, my DMM (very cheap, $16) reads 37.2V... is the rated voltage (ie, 30V) the RMS value??

If it is the RMS value, is it safe to run the 37.2V measured through a 35V capacitor, assuming 37.2 = Vpeak?

If the 37.2 is too high, can i drop the voltage using parallel reversed diodes, or will this rectify the signal??

cheers

g

 

[guzzler]

^ bump ^

could really use a hand with this one!

g

 

[jarthel]

why not post the question in other forums like headwize, diyaudio or audioasylum?

Head-fi isn't the only forum that deals with DIY electronics.

I'm sure the forum's owner/moderators wouldn't mind that you post the same question to different forums.

That's why I post my questions to several forums so I have more chances of getting a reply.

 

[jeffreyj]

Quote:

Originally posted by guzzler I've just enclosed a 15-0-15 transformer wired in series to give a nominal 30V output... however, my DMM (very cheap, $16) reads 37.2V... is the rated voltage (ie, 30V) the RMS value?? If it is the RMS value, is it safe to run the 37.2V measured through a 35V capacitor, assuming 37.2 = Vpeak? If the 37.2 is too high, can i drop the voltage using parallel reversed diodes, or will this rectify the signal?? g

The voltage to which the filter capacitor(s) will charge will be the peak voltage, not the rms, so multiply your 30Vrms by 1.414. Of course, you can take a volt or two off for the diode drops in a bridge, but that'll still be a long ways away from 35V. 50V capacitors would very much be necessary in this application.

The circuit you posted will, indeed, reduce the peak voltage, but it will also increase the harmonic content of the "sine wave" by putting a noticeable pause in the transitioning from one polarity to the other.

 

[guzzler]

ok cheers jeff... i'll have to desolder my old 35V and go and get me a 63V one!

g