gusfinley said:I've been messing around with these comparator circuits and I'm having a but of trouble getting them to work right...
Let me be a little more specific, I have half of an NE5532 opamp remaining after building my preamp, so I am hoping to use this as the comparator. I want my "clip" led to turn on just before I reach the 5V peak to peak limit of the Analog-to-digital convertor. The supply rails on the opamp are +12V and -12V.
Am I comparing my voltages wrong? I am comparing a DC signal with an AC signal, and perhaps that is causing some trouble. Perhaps the +12V and -12V rails are causing trouble? I'm not sure... but something is a little screwy!!
mshilarious said:Did you see the schematics I linked? You need to divide the +12V supply to create a +5V reference for the opamp. Then when the signal hits +5V, the LED will light. It doesn't matter that it lights in a half-rectified manner, you can use a cap to smooth out the LED's blinking.
gusfinley said:yeah, I've created a voltage divider to give it a reference of 2.4V (max for half of the wave) but as soon as I plug it into the opamp terminal the voltage is no longer 2.4V. Wierd stuff like this keeps happening when I wire up the circuit. I works just fine in simulation, but when I wire it up its a different beast.. perhaps I'll go back to the transistor clipping indicator, but I wouldn't really like something that is non-linear....
mshilarious said:How much current to you have in the divider?
gusfinley said:not much. (.2mA or so) I used a 50K pot to set the reference voltage level.