Assistance in wiring a simple circuit?

[things]

Any idea's why i would have got 12V on the output though?

I'll plug it back in and tweak it some more...

 

[ericgibbs]

Any idea's why i would have got 12V on the output though?

I'll plug it back in and tweak it some more...

Could be any or all of these:

Blown opa.
missing -V supply.
open neg feedback loop.
high -v input and gain R5 set too high.
EDIT: or R4 is not set correctly.[ the -5V ref]

or you not measuring it correctly.

 

[things]

Hi, the 1K resistor is supposed to limit the voltage to like 5V right?? I measerud the voltage of the PSU, between +15V and -15V, and its like >20V !!

Does that mean: 15+15=30V ??

 

[ericgibbs]

Hi, the 1K resistor is supposed to limit the voltage to like 5V right?? I measerud the voltage of the PSU, between +15V and -15V, and its like >20V !!

Does that mean: 15+15=30V ??

hi,
The 1K limits the current thru the 5V zener.
The voltage across the zener should be about -5V.
The junction of R2 and R5 should be -5.1V with respect to 0V.

Measuring from +15V to -15V should read 30V.

 

[things]

Ahh damn, im not thinking straight. Sorry Eric, I found out that I had the + hooked up to pin 5, instead of 8 LOL!!!

Anyway, what do I need to do with both of the pots?

Thanks for all the help!

 

[ericgibbs]

Ahh damn, im not thinking straight. Sorry Eric, I found out that I had the + hooked up to pin 5, instead of 8 LOL!!!

Anyway, what do I need to do with both of the pots?

Thanks for all the help!

hi,
Do this:
Disconnect the TL072 from the sound card signal, you can leave the ground and power line as they are.

For both TL072's
Now connect R1 marked '1' to 0V

Set R4 to a value of 10K [ that will give a OPA gain of 1]

Adjust R3 until pin 1 of the TL072 reads +2V

Connect the output of the sound card [recall its got +2V sitting on it]. back onto R1

The outputs of the TL's should now be close to 0V.

Let me know what you get.

 

[things]

hey Eric, I have done that, and end up with a 0 without sound, and a 4.97 maxed out fully. So that is all good, but I am still having that huge distortion problems. Any idea's what could be causing this?

Thanks

 

[ericgibbs]

hey Eric, I have done that, and end up with a 0 without sound, and a 4.97 maxed out fully. So that is all good, but I am still having that huge distortion problems. Any idea's what could be causing this?

Thanks

hi,
Distortion could be due to a number of causes, overdriving the inputs or outputs is common.
Keep the input levels lowish.

How are you driving the sound card input.?
Whats on each channel.?

Do you have a scope.?

You did say the galvo amps are differential, how are the inputs connected.?

Sorry so many questions, I can't look over your shoulder.

 

[things]

The sound card is being driven with a software called "Spaghetti". which is a laser show controller that supports using a sound card.

I require atleast 3 channels out of it, to control X, Y and the green laser.

No I don't have a scope, and I am giving the differential amps thier signal, as shown in the last diagram I posted. I have gone through windows and looked for any EQ's that might be screwing with it, but found nothing..

 

[ericgibbs]

The sound card is being driven with a software called "Spaghetti". which is a laser show controller that supports using a sound card.

I require atleast 3 channels out of it, to control X, Y and the green laser.

No I don't have a scope, and I am giving the differential amps thier signal, as shown in the last diagram I posted. I have gone through windows and looked for any EQ's that might be screwing with it, but found nothing..

hi,
As you have no scope, we will do a quick 'dc' test of the OPA/galvo's

Look at the attached dwg.
Connect a voltage divider chain VR1 etc as shown in the dwg.

This test will check the OPA's and galvo's
Make a note and post the results of the tests.

OK.?

 

[audioguru]

The TL072 has two opamps inside. You are not using the second opamp and are using two dual opamps instead of just one.

Maybe the loops are the opamps oscillating.
The TL071, TL072 and TL074 opamps are fairly wideband and oscillate at a high frequency when they directly drive the capacitance of a shielded output cable. Add a 100 ohm resistor in sreies with the output of the opamp and the shielded cable that goes to the galvo amplifier input to isolate the cable capacitance from the output of the opamp.