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Op Amps
Jan 10, 2019 10:27:17 GMT -6
Post by keymod on Jan 10, 2019 10:27:17 GMT -6
How does a novice builder, without a lot of intricate testing equipment, test an op amp build to make sure it is working correctly? Can it be done simply with a good DMM? Don't want to plug one into a good piece of gear and risk blowing something up, LOL.
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Post by winetree on Jan 10, 2019 11:09:42 GMT -6
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Post by matt@IAA on Jan 10, 2019 13:06:36 GMT -6
You can do it with a breadboard and some banana clips. The fivefish audio tester is really easy. You can't do it just with a DMM because you need to provide power to it. In, out, some kind of feedback loop (with or without resistor/capacitor) rounds it out.
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Op Amps
Jan 10, 2019 14:24:28 GMT -6
Post by keymod on Jan 10, 2019 14:24:28 GMT -6
But, for either one of those, it seems you need an oscilloscope??
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Op Amps
Jan 10, 2019 19:43:06 GMT -6
via mobile
keymod likes this
Post by matt@IAA on Jan 10, 2019 19:43:06 GMT -6
Nah. Set it up as a balanced receiver and send a signal to it from your interface. You can either record the unbalanced output or measure it with a DMM.
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Post by Blackdawg on Jan 11, 2019 11:50:19 GMT -6
What exactly are you measuring though? Like what means it's a good opamp? I'd like to do this to mine too.
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Post by matt@IAA on Jan 11, 2019 15:22:26 GMT -6
What exactly are you measuring though? Like what means it's a good opamp? I'd like to do this to mine too. With an interface you can do RMAA and check THD and frequency response. With a square wave input and a scope you could measure slew rate. With a signal analyzer you could also do THD and see the FFT for even and odd order harmonics. I suppose you could find a way to measure CMRR as well. Generally though, most op amps are going to be nearly indistinguishable at normal levels and output loads. If it passes audio, and you built it with the spec components, then it’s “right”. I guess you could check DC gain and stuff, too. Dunno. |
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Post by matt@IAA on Jan 11, 2019 18:31:51 GMT -6
You can generate a THD comparison like this in RMAA. Its free. This is two op amps swapped out on a circuit.  |
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Post by matt@IAA on Jan 16, 2019 18:54:14 GMT -6
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Post by Blackdawg on Jan 16, 2019 19:14:24 GMT -6
Nice that was very informative. |
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