I'm trying to build a twin-T oscillator for synthesising drum sounds. The LM741 heats up pretty quickly and the circuit hardly oscillates even when the feedback is at 100 per cent. Even with an LM386 amp I hardly get anything (though I can see some oscillation on the scope). The circuit gets 10ms 5V pulses from an Arduino. Does the TL071/2 run from single supply? Can it replace the LM741?


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    \$\begingroup\$ 1. Any op amp can run from a single supply. 2. It is difficult to tell what is actually being asked here. Please post a schematic. \$\endgroup\$ – Matt Young Apr 13 '13 at 5:14
  • \$\begingroup\$ Schematics here: flickr.com/photos/alkopop79/8644385451 \$\endgroup\$ – alkopop79 Apr 13 '13 at 12:09
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    \$\begingroup\$ I suspect a capacitor in series with the output would improve behaviour - at the moment it's effectively DC-coupled the output to ground. \$\endgroup\$ – pjc50 Apr 13 '13 at 12:49
  • \$\begingroup\$ What is the power supply voltage being used? \$\endgroup\$ – Anindo Ghosh Apr 13 '13 at 12:54
  • \$\begingroup\$ circuitlab.com/browse/by-tag/drum Your output loads your (-) feedback loop. \$\endgroup\$ – Optionparty Apr 13 '13 at 14:31

It's working now. I replaced the 741 for a TL072 and a resistor had to be replaced for a larger one (the 2.2M). As for the split rail, I made a simple rail splitter that converts 9V to 4.5V, 0V and -4.5V.

  • \$\begingroup\$ The circuit here: circuitlab.com/circuit/g52648/screenshot/1024x768 \$\endgroup\$ – alkopop79 Apr 14 '13 at 20:15
  • \$\begingroup\$ You could also checkout LM324 \$\endgroup\$ – abdullah kahraman May 14 '13 at 21:12
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    \$\begingroup\$ A rail splitters does not convert 9V to +/- 4.5. That's a misleading way to look at it. Your circuit is powered on 9V. Ground is at 0V. What the splitter circuit does is provides a bias voltage reference. That reference isn't a real ground. It cannot sink current like a real ground. You should not use the ground symbol for that node. \$\endgroup\$ – Kaz May 14 '13 at 21:13

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