Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Solid State => Topic started by: TIMBO on July 07, 2012, 09:20:57 pm
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Hi guy's, Can't quite get my head around this one. I built a little onboard treble boost circuit just as an added effect but i can't work out how it should be grounded.
The transformer that powers the heaters is the first transformer in a back to back setup and i am using the 12vac tap for the heaters and the 15vac tap to a voltage regulator to power the treble boost circuit.(normally the boost circuit is run on 9vdc but can be run at a little higher voltage for added headroom)
The heater circuit 0v is not grounded as it is part of the back to back setup and the treble boost regulator circuit 0v is also not grounded as it is part of the back to back transformer circuit as well.
This means that the regulator circuit is FLOATING and the boost circuit ground is using the AMPS GROUND as its ground.
Is this OK???
The circuit is not working very well HUMMING and not producing the desired effect.
The circuit provides voltages at various points in the boost circuit but i get different readings as i do not know if i should be grounding the MM (black lead) to the regulator 0v or the amps ground???Thanks
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> part of the back to back transformer circuit
Not shown in your plan, so can't comment.
> the regulator 0v or the amps ground???
Should be the same thing.
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PRR, I am sure that i am unable to use the back to back transformers to power the regulator circuit but my thinking was the REGULATOR part of the circuit could be floating but this does not seem to be the case.
I bypassed the regulator and clipped a 9v battery to the boost circuit and it worked well. So now my thinking is that like a normal FX pedal the ground of the FX and FX power supply use the amp ground as part of its circuit :think1:
So a separate small transformer used to power the regulator is required as you have said, the regulator and boost circuits should have the same ground.
The first schem is what i thought i could do by just tapping off the 15v and 0v tap to power the regulator.
The second schem is what i think i NEED to do.Thanks