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Question for J. Orman: Minibooster

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9/8/1999 12:55 AM

Question for J. Orman: Minibooster

Jack: As I've said before in these parts, the Minibooster is one of my favorite effects. Lately I've been using it quite a bit, and maybe I'm developing ears like Eric Johnson's (grin), but I can tell when the voltage gets even half a volt below fully charged.

Looking at the push-pull setup, I can't really get a handle on what R_LOAD of the circuit is. Could you give me a quick theory lesson on this circuit? Would you classify this circuit as...how shall I put it..."battery intensive?"

9/8/1999 8:14 AM
Stan Bailey	I too would like a theory lesson. I showed it to my electronics teacher and he made the comment: "I wander was he's trying to do here". He only had a second to look at it, but it left me wandering. Stan

9/8/1999 11:51 AM
R.G.	Which circuit is it? If it's the stacked JFETs, that is a JFET copy of an old triode circuit where one tube provides an active load for the other. If you'll note the URL for the circuit you're using, I'll do a dig into it.

9/8/1999 1:32 PM
Fuzzman	>If it's the stacked JFETs, that is a JFET copy of an old triode circuit where one tube provides an active load for the other. I've seen lots of tube cascode circuits but never that one, where can I find it? Do you have a URL or other source I could look up? I'm familiar with the mic preamp on Pat's Schematics page.

9/9/1999 2:24 PM
Jimi	>>> that is a JFET copy of an old triode circuit I emailed Jack and asked him about this. Maybe we'll see what he has to say if I get a response. Glass Audio has published numerous tube cascode circuits. GA is online at http://www.audioxpress.com J2K

9/12/1999 1:58 PM
R.G.	It's not a cascode. It's a constant current source load on a basic common source gain stage.

9/8/1999 3:22 PM
Joe Fuzz	Hi, R.G. Nice to talk to you again! Well, I had to do some digging but I found it out at the PCB site: http://www.lazyfinger.com/mini/mini.gif As you can see, it is the stacked JFET arrangement you alluded to. I really like this circuit so any light you can shed on it would be great.

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