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previous: Charlie Thanx for all the input ;-)... -- 5/11/2000 1:10 AM

Re: Circuit problem...revised...

5/11/2000 3:28 AM
R.G.	Re: Circuit problem...revised... Well, good folks, we got trouble, yes trouble, right here in River City - That's "trouble" with a "T" and that rhymes with "B" and that stands for.... Bluesbreaker... Pin 4 is where Ground goes. The opamp can't work unless this is zero volts. Likewise, pin 8 is where the power goes. This should be battery voltage, around 9V. An opamp can't be operating linearly if all three pins for the opamp (that's +input, -input, and output) aren't all within a few millivolts of the same DC level. In the case of the Blues Breaker, there is a 4.5V DC level generated and applied to one +input directly, and to the other through a 1M resistor. So - looks like wiring or parts value problems. In any case, nothing will work until you get 9V on pin 8 and 0V on pin4. Use your ohmmeter to see what the DC resistance is from these pins back to the battery clip. I bet they're not 0 ohms.

5/11/2000 3:28 AM

R.G.

Re: Circuit problem...revised...

Well, good folks, we got trouble,
yes trouble, right here in River City -
That's "trouble" with a "T"
and that rhymes with "B"
and that stands for.... Bluesbreaker...

Pin 4 is where Ground goes. The opamp can't work unless this is zero volts. Likewise, pin 8 is where the power goes. This should be battery voltage, around 9V. An opamp *can't* be operating linearly if all three pins for the opamp (that's +input, -input, and output) aren't all within a few millivolts of the same DC level. In the case of the Blues Breaker, there is a 4.5V DC level generated and applied to one +input directly, and to the other through a 1M resistor.

So - looks like wiring or parts value problems. In any case, nothing will work until you get 9V on pin 8 and 0V on pin4. Use your ohmmeter to see what the DC resistance is from these pins back to the battery clip. I bet they're not 0 ohms.