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previous: Mike I. Checked my CMOS manual and the CD40... -- 4/25/2000 5:04 PM

Re: Pearl Phaser

4/25/2000 7:14 PM
GFR	Re: Pearl Phaser My first guess was a CMOS hex inverter but 1) pin 7 goes to the LFO and 2) pin 14 goes to a comparator + transistor inverter + capacitor load from pins 8&9. 3) No pin to ground or Vcc. On the Bad stone pin 8 goes to ground and pin 16 goes to B+ plus LFO, together with some other pins. 4) The controlled resistance pins go to a "B1" voltage through some very big resistors (220K) and 5) also have some very big resistors in parallel (680K). On the bad stone there's a smaller resistor (27K) going to ground. On the bad stone it looks like the "bottom" mosfet of each inverter is used as a variable resistance (Rds) by varying each Vgs while the "top" mosfet is off. Maybe it's cmos inverters, but then they're working differently from the Bad Stone. I'll also take a look at the ETI cmos phaser (it only uses cmos inverters) to see if it's similar.

4/25/2000 7:14 PM

GFR

Re: Pearl Phaser

My first guess was a CMOS hex inverter but

1) pin 7 goes to the LFO and
2) pin 14 goes to a comparator + transistor inverter + capacitor load from pins 8&9.
3) No pin to ground or Vcc.

On the Bad stone pin 8 goes to ground and pin 16 goes to B+ plus LFO, together with some other pins.

4) The controlled resistance pins go to a "B1" voltage through some very big resistors (220K) and
5) also have some very big resistors in parallel (680K).

On the bad stone there's a smaller resistor (27K) going to ground.

On the bad stone it looks like the "bottom" mosfet of each inverter is used as a variable resistance (Rds) by varying each Vgs while the "top" mosfet is off.

Maybe it's cmos inverters, but then they're working differently from the Bad Stone. I'll also take a look at the ETI cmos phaser (it only uses cmos inverters) to see if it's similar.

Replies:

Mike I. Just took a look at the ETI schemat... -- 4/25/2000 11:38 PM