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I am working on a schematic that requires the operational amplifier MC34072P but I couldn't find it here in local stores! So, anyone would suggest any substitute to use? I'd be grateful. And by the way, what are the basic things should I look at in specs to compare such ICs? Thanks in advance!

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"The basic things to compare such ICs" should come from you. It will be the application which says whether the MC34072 was chosen for its fast settling time or its large capacitance drive capability. So, why did you choose that one in the first place? – stevenvh Aug 25 '12 at 15:01
Digikey is often a good place to look. They will deliver in many countries. where are you located? – Russell McMahon Aug 25 '12 at 15:56
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@Russell - I use the Digikey site often because of the fine selection tools, and for price indications. But AndrejaKo complains that shipping abroad can be prohibitively expensive, like his 120 dollar example says. I find it too much for an opamp, anyway. – stevenvh Aug 25 '12 at 16:13

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"I want to amplify a signal coming from audio stream (audio signal) so that I filter it and deliver it to LED making a LED organ."

Good news: almost any opamp can handle this, so that I wonder how you got at the MC34072P, especially since you can't find it. You don't need a high bandwidth or slew rate, or low noise and distortion.

Your main requirements will be power supply and output drive. The LM358 can source minimum 20 mA, typical 40 mA which is probably enough to drive your LED. This current is specified at +15 V supply however, so if you only would have +5 V you might get less. You can always use the opamp's output to drive a transistor.

Don't use a dual supply, like +/- 15 V. If the output would go -15 V the negative voltage will destroy the LED or transistor.

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The MC34072P appears to be at End of Life.

Two available options that are (nearly) equivalent include MC34072PG, and MC34072VPG, as well as MC33072PG.

You can see the results of my search here at this page on Mouser. On that page, you can broaden the parameters (i.e., remove some of the filters) to see more part options.

Method of searching for parts similar to any PartXYZ, for the future

  • You can use the Search tool of a seller/distributor website like Mouser or Digikey.
  • Find page of PartXYZ on the website.
  • Go to the parent category containing the part, ideally in a new window/tab.
  • Then on this category listing page, you will see a Search tool (which will now search within the category you just chose).
  • For the Filter parameter options, set the parameters equal to the ones of PartXYZ, especially the parameters that are important to you.
  • The Search tool of the website should now give you various options similar to, and including, PartXYZ.

Specs to look for in opamps: Gain, Bandwidth, Noise, Offset voltage/current/drift, Bias current, Output impedance, Slew rate, CMRR, Packaging, Price ... And so on; depends on what your application needs really.

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If the local store doesn't have the MC34072P there's a great chance that they won't have the MC34072VPG either. Nothing to do with end of life, but with storing more common types, like 741 and LM358. – stevenvh Aug 25 '12 at 15:12
@stevenh: A good point that I didn't even consider. Siraj Muhamamad: Providing details regarding why you chose that part would help (you/others) find a meaningful replacement. – boardbite Aug 25 '12 at 15:23
@boardbite I chose that part because I want to amplify a signal coming from audio stream (audio signal) so that I filter it and deliver it to LED making a LED organ. And thank you very much for your precious info. – Siraj Muhammad Aug 25 '12 at 22:10
I'd like to thank @stevenhv for his comment, but do I understand that LM741 and LM358 could be a replacement? and now you know why I want the part for? and thanks a lot! – Siraj Muhammad Aug 25 '12 at 22:14
up vote 1 down vote

If you're not tied to some super-special characteristic of the MC34072, I suggest you use the TL072. The TL071/TL072/TL074 series are very common and very widely used JFET-input OpAmps, and I think it's even safe to assume than Motorola (now OnSemi) introduced their MC34071/2/4 series OpAmps as a second source for TI's parts.

For most applications, both types will likely work as interchangeable drop-in replacement parts.

There's no trouble at all obtaining the TL07x parts.

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