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Hoffman Amps Forum image Author Topic: building a bias circuit from tranformer using full wave bridge and no center tap  (Read 5091 times)

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Offline Tone Junkie

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Ive tried using the standard method just going off one side and building a marshall type bias circuit but it hasnt worked for me. any insite on how to do it properly.
Thanks Bill

Offline kagliostro

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Quote
Ive tried using the standard method just going off one side and building a marshall type bias circuit but it hasnt worked for me.

Please give other infos

Is this the schematic you followed ?

Kagliostro
The world is a nice place if there is health and there are friends

Offline Tone Junkie

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No but that one looks like its worth a try.
Thanks Bill

Offline kagliostro

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Look to Sluckey's Amp Scrapbook (the origin of that schematic)

there is also one other way to skin the cat

the Typical Marshall way (right & top of page 5)

http://home.comcast.net/~seluckey/amps/misc/Amp_Scrapbook.pdf

Kagliostro

p.s.: Thanks to Sluckey sharing that file



The world is a nice place if there is health and there are friends

stratele52

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Ive tried using the standard method just going off one side and building a marshall type bias circuit but it hasnt worked for me. any insite on how to do it properly.
Thanks Bill
No but that one looks like its worth a try.
Thanks Bill

Which Marshall you make and does'nt work ?

Offline Tone Junkie

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Stratele52 I had a transformer that I had to use a full wave bridge because it didnt have HV center tap and when I did the standard marshall take off from one side like they use on the plexi amp it didnt work. I didnt have a marshall I just use that scheme alot.
I was actually making a trainwreck with spare parts I had laying around, i thought what the heck I can get what I needed from that transformer I just didnt do my home work first.
I will implemant one of the 2 ways shown in the morning.
Thanks Bill    
« Last Edit: December 20, 2011, 01:46:58 am by Tone Junkie »

Offline eleventeen

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You have to include the series capacitor if you're going to come off one side of a bridge rectifier. This is done in Bogen amps. You see it a lot more when the main rectifier is a half-wave diode voltage doubler.

Offline Tone Junkie

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Thanks guys I like comming here and asking questions I always learn something good here.
Bill

Offline Tone Junkie

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Worked perfect guys thanks.
Bill

Offline kagliostro

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Glad you solved the problem  :smiley:

Kagliostro
The world is a nice place if there is health and there are friends

 


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