Norty,
The scanner +/- 24 is seven to ten volts too high for most opaps. LM7815 and LM7915 are low cost Voltage regulators (1.75$) that will solve your problem by creating +/- 15V/ I normally do not suggest running signal processing off the scanner supply, but for the low currents you need, the LM series regulators will supply some isolation. They need a small capacitor pair on their outputs (0.1 uf ceramic, 220 uF 24 or 48V electrolytic).
LM3900 is a Norton Current differencing chip, is referred to as a Op-amp by mistake. It uses a different circuit layout, is not for beginners and has poor stability and bandwidth. It has its uses in automotive and scientific applications, but is not ideal by any means for laser show. LM324 is a horrible, outdated, bipolar device with huge distortion. Go for the TL084 family.
If your buffering color signals, let me know and I'll draw out the "Clamp" circuit that will protect the flexmods against reverse polarity. If there is any chance that the opamp will be miswired or the inputs left floating, you will need the overvoltage and reverse polarity clamps.
Steve
Last edited by mixedgas; 07-05-2014 at 07:14.
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