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Powering OPL3 module from +-5V?


Sauraen
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Yes and no. To voltage on the opamp limits the maximum input/output voltage they can reproduce without clipping the signal. If you simply lower the voltage from +-12V to +-5V you'll potentially clip 7V on either end of the signal. The resistors need to be adjusted, not to raise the gain, but to lower it.

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I most certainly can. Have a schem :flowers: This is only for one of the YACs, the other one is identical.

The DACs on the mbFM output a signal of 0..5V (what else could they do, they're powered by 5V). So it seemed only natural to simply buffer that signal and output it, rather than turn it into a bipolar signal (+-12V), which requires additional voltages. Since regular opamps can only have in/output voltages up to ~1.5V of their power rails, I went with a rail-to-rail amp, that lets the signal get very close to the rails. The voltage divider made up of R52/R56/R57 and R53/R58/R59 lowers the signal to roughly 0.4V - 4.6V, centered around 2.5V to prevent clipping.

sammichFM_base_rev1_output.pdf

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I already have +-5V power rails in my build, so how about this: Output of DAC goes through 10uf coupling capacitor, becomes -2.5 to 2.5 volts. Run this through unity-gain buffer made from normal non-rail-to-rail op-amp powered from +-5 volts. I've been experimenting with the LF412 op-amp and it clips at +-4.17 volts when powered from +-5, so that should be enough. Does this sound good?

Also, do the sample-and-hold op-amps for the DAC need to go rail-to-rail? If so, I would need to make IC3 and IC5 on the MBHP_OPL3 board TLV2774 rail-to-rail op-amps powered from +5 volts, and then make IC6 a normal op-amp like LF347 powered from +-5 volts. And somehow insert the coupling capacitors between the two...

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