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previous: amz-fx [QUOTE]Please tell me you recently ... -- 12/18/2002 12:47 AM view thread

Re: Queen Triggered Wah

12/19/2002 6:25 PM
carlo
Re: Queen Triggered Wah
Jack, thanks for the laugh as well as the explanation.  
 
quote:
"...the 9v battery is setting the reference voltage on its base."
 
 
So the battery is still being used when the external ac is plugged in.... is it necessary? Meaning, will the unit work with external ac and no battery?  
 
quote:
"The opamp is providing drive for a reference voltage used as a pseudo-ground."
 
 
Cool.... this explains why what i assumed was the ground plane on the pcb isn't connected directly to chassis ground. I noticed that all the polarized caps that go to this pseudo-ground have the + end connected to it.  
 
quote:
"What happens if there is no ac adapter plugged in? The 9v power flows through the base-emitter junction of Q4 which acts as a diode."
 
 
Is the battery still connected to D9 in this case? In other words, is the external ac input switch, (no ac adapter plugged in), normally closed?  
 
Looks that way in the diagram, but the ac switch on the pedal is normally open. The ac switch and tip connections are reversed on the pedal, compared to the schematic, so for now i just connected the battery + to the base of Q4. The pedal is working, but the  
bypass foot switch is intermittent and the LP/BP foot sw is not functioning.  
 
much appreciated,  
carlo

 
Replies:
carlo anyone?... -- 12/28/2002 4:21 PM