I have a PT transformer that specs. 300-0-300 and need a 300-45-0-300. I was hoping to use the one I have the 300-0-300 and step down the voltage for the bias 45volt leg requirement. Will this work? If so what size resistor is required to step 300 down to 45 volts. I tried a 475k and still have over 100 volts.
Thank you in advance, Shawn
TRANSFORMER PROBLEM
Moderators: pompeiisneaks, Colossal
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Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: TRANSFORMER PROBLEM
ampegs used the same approach...... they used a 100k or 220k
connected to a 56k resistor to ground as a voltage divider
and fed the bias rectifier from that junction
youll have to fiddle with the values of the pot. a resister to ground at the end
of the circuit for your application and available parts.... this example used
a 15k pot. and a 33k resistor
connected to a 56k resistor to ground as a voltage divider
and fed the bias rectifier from that junction
youll have to fiddle with the values of the pot. a resister to ground at the end
of the circuit for your application and available parts.... this example used
a 15k pot. and a 33k resistor
lazymaryamps
Re: TRANSFORMER PROBLEM
What Andy said...I think you aren't constructing in properly. In addition, look at the typical Marshall circuit for a helpful hint -- JTM45 comes to mind; other models are good, too. For a Fender reference, maybe AA964 is a good reference.