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previous: Aron On the memory man schematic: -- 10/10/1999 6:41 AM

Re: Need +15 volts from schematic

10/11/1999 2:36 AM
Don Symes	Re: Need +15 volts from schematic Something to notice - the 4047, a CMOS logic part with VDD at pin 14 and VSS at pin 7 - is being run with VDD at GND, and VSS at some negative voltage (didn't notice if -15 or what). For some reason, they're running this circuit 'upside down'. I also failed to find where B1, B2, etc go. Is there another page or some stuff missing? Flipping the circuit over to run from a 'positive' supply shouldn't be too tough. The IC pins at GND go to +15, the pins at -15 go to gnd. The opamp and transistor biasing will have to be re-thought. Any particular reason for your concern?

10/11/1999 2:36 AM

Don Symes

Re: Need +15 volts from schematic

Something to notice - the 4047, a CMOS logic part with VDD at pin 14 and VSS at pin 7 - is being run with VDD at GND, and VSS at some negative voltage (didn't notice if -15 or what). For some reason, they're running this circuit 'upside down'.

I also failed to find where B1, B2, etc go. Is there another page or some stuff missing?

Flipping the circuit over to run from a 'positive' supply shouldn't be too tough. The IC pins at GND go to +15, the pins at -15 go to gnd. The opamp and transistor biasing will have to be re-thought.

Any particular reason for your concern?

Replies:

Aron I gave up. I understand how it work... -- 10/11/1999 3:19 AM
AMZ The circuit uses a negative voltage... -- 10/11/1999 9:34 AM