Why isn't this working? Revisited...

[ExpAnonColin]

Well, it's just not working.  The little diagram on the side is vbias, right?  And I should be connecting where the circuit asks for V- to the "black" side of the 9v?

Something isn't going right..

-Colin

[Ansil]

on a dual opamp take pin 4 and put it to ground.
take the voltage bias.. and series it with a 1meg resistor and put it on pin 3.

that should help

[ExpAnonColin]

on a dual opamp take pin 4 and put it to ground.
take the voltage bias.. and series it with a 1meg resistor and put it on pin 3.

that should help

So, basically, NOTHING should be connected to the 9v's "black wire"?

-Colin

[ExpAnonColin]

Sorry, ansil, but it's still not working... thanks for the suggestions, though.

-Colin

[Peter Snowberg]

Your Vbias is correct as well as the power connections. Are you getting any oscillation on the outputs at all?, and what voltages do you see on pins 7 and 1?

If you look at this circuit on the scope, use AC coupling.

There must be an answer.

Take care,
-Peter

[ExpAnonColin]

Your Vbias is correct as well as the power connections. Are you getting any oscillation on the outputs at all?, and what voltages do you see on pins 7 and 1?

If you look at this circuit on the scope, use AC coupling.

There must be an answer.

Take care,
-Peter

Actually, funny as it may sound, I've been looking at everything little aspect of it on a scope-I'm getting no waveforms and no real voltage out of pins 7 and 1.  Using AC coupling, too...

Hmm hmm hmm..

I highly doubt the op amp is messed up, but I guess it's possible.

-Colin

[Peter Snowberg]

When you say no voltage, are you talking zero on the outputs? That would point to a bad opamp.

To test it out, wire the opamps up as unity gain followers by connecting the - inputs to their respective outputs and connect the + inputs to your Vbias. Check using your meter for 1/2 Vcc at the + inputs, and if you get that, you should see the same voltage at the outputs. I love breadboards.

Take care,
-Peter

[ExpAnonColin]

When you say no voltage, are you talking zero on the outputs? That would point to a bad opamp.

To test it out, wire the opamps up as unity gain followers by connecting the - inputs to their respective outputs and connect the + inputs to your Vbias. Check using your meter for 1/2 Vcc at the + inputs, and if you get that, you should see the same voltage at the outputs. I love breadboards.

Take care,
-Peter

Well, with my scope, there's always some latent interference going around... when I say no voltage I mean just your standard fuzzyness going on when you have it set on 5mv.  I'll try doing that now quick...

-Colin

[Paul Perry (Frostwave)]

So, basically, NOTHING should be connected to the 9v's "black wire"?

-Colin

Well, ground (earth) has to be, of course.
Also, the circuit is now running at 9v total supply, not the original 18. Whihc I wouldn't expect to see stop it, but You Never Know.

[Peter Snowberg]

Thanks Paul, I missed that comment. I was looking at the original message...

And I should be connecting where the circuit asks for V- to the "black" side of the 9v?

-Peter

[puretube]

bear: multiply the values of all resistors by 10....

[Thomas P.]

At the moment I simulated this circuit and it worked. Nice triangle and square waves.

[puretube]

err...
s.b. mentioned already, that pin 4 is to be connected to the minus (black wire of the batt.) 9V AND to the ground? (i.e.: it IS ground)

[Ge_Whiz]

Will the 4558 work with a supply of only +/- 4.5V? try plugging in an '072 or similar?

[ExpAnonColin]

So, basically, NOTHING should be connected to the 9v's "black wire"?

-Colin

Well, ground (earth) has to be, of course.
Also, the circuit is now running at 9v total supply, not the original 18. Whihc I wouldn't expect to see stop it, but You Never Know.

So I DO have th negative ground it.

Tomboy-that makes me pretty jealous!  I guess I'll just start from scratch again.

-Colin

[Thomas P.]

Well, that it works during an simulation doesn't have to say that it works in the real world :wink: