Questions about the Low Voltage Booster article on AMZ...

[amonte]

I read over this article and wanted to start exploring some of the concepts using a pedal that I'm currently breadboarding, but I've got some questions.

First, I know the article explores the possibility of using alternate power sources such as AAA or AA batteries.  I don't think this would be a problem, but could I simply use a 9V battery and add resistance to the +9V lead to drop it down to +3 or +1.5V?

Second, I understand that in order to bias the transistor, I need to bring the collector down to 1/2 of the source voltage.  Do I need to make changes to the other resistors involved in biasing the transistor or will it work with just tweaking the collector resistor?  If so, what target voltages should I be shooting for on the emitter and base?

Thanks!

[petemoore]

I read over this article and wanted to start exploring some of the concepts using a pedal that I'm currently breadboarding, but I've got some questions.

First, I know the article explores the possibility of using alternate power sources such as AAA or AA batteries.  I don't think this would be a problem, but could I simply use a 9V battery and add resistance to the +9V lead to drop it down to +3 or +1.5V?
  I used an LM317 voltage regulator...knob adjust works great for this.
Second, I understand that in order to bias the transistor, I need to bring the collector down to 1/2 of the source voltage.  Do I need to make changes to the other resistors involved in biasing the transistor or will it work with just tweaking the collector resistor?  If so, what target voltages should I be shooting for on the emitter and base?
  A Jfet amp stage may need bias resistor adjustment for 'extreme' or lower voltage...where you get the cool compression/mild distortion. I think it's in the ariticle...
  I have a nice 'Mu>Starved MU' circuit, mu amps are self biasing, lending themselves well to this sort of thing...I got nice biases past lower voltages I liked.
  I tried
Jfet stage
Bipolar stage
Bipolar into Jfet
Jfet into Jfet
Jfet into mu
Mu to Mu
   Starving both stages...cool
  Starving the first stage only
Starving the second stage [boost into it an unstarved stage ]
  I have a nice Mu>Starved Mu circuit, really cool sounds with this one.
  A little breadboard would come in handy, I used perf and some well placed sockets.

Thanks!

[amonte]

Thanks for the reply - the LM317 looks pretty cool.  I'll have to read through that tutorial all the way. 

What I've been doing with the circuit on my breadboard is limiting the voltage going to the collector.  I've got a pot going to the collector that swings the voltage and I've been experimenting with everything from 2.5 to 8.0 going to the collector.  It starts to get really interesting towards the lower end, though the overdrive is a little "loose" and can get a bit flabby. 

Question - what is the difference in sound between starving the collector as opposed to starving the circuit?  Might starving the entire circuit help tighten things up a bit?

BTW - I've also got a bypass cap on the emitter, so the transistor is pumping out a nice amount of overdrive.  In fact, I had originally thought about combining clipping diodes with the clipping from the transistor, but just the results of pushing the transistor alone is making me consider leaving the diodes out.  Or, perhaps mixing the two outputs (direct from the transistor and output with clipping diodes) together.