Oh datasheet from texas instruments also said LM432 is similar to LM358, lol
Yes that is correct. But once biased properly the results are easy to see on the scope picture of the actual device and it shows a clean waveform.The LM358 dual and LM324 quad do not produce crossover distortion when they drive a resistor connected to ground like you did or to the positive supply because then one of the output transistors operates in class-A (and unfortunately gets hot).
They work fine within the specs they were designed for just like any other op amp would work with the same specs. Not all op amps are designed to put out 50 megaamperes at 2 gigahertz with a slew rate of 50 megavolts per microsecond. Any op amp with a GBW of 1MHz and slew rate of 0.5v/us will act the same way. If you want faster then you look for faster, but if you dont need faster than you can use ANY op amp with these specs, and ANY includes this one.Also since they are low power and do not have enough bias current for their class-B output transistors then the slew rate is so low that they have trouble with frequencies above 2kHz when the output level is high.
In #1 above you said the crossover was eliminated with the proper output biasing, so no need to rethink this aspect of it. It doesnt really matter that the gain was 1 i used that because it was easier to set up the test and besides using this for a buffer is a common use anyway. But the 10kHz attenuation idea is just not correct because the 2v peak wave looks the same at 100Hz, 1kHz, and 10kHz, and those three frequencies were used for the tests. Of course the slew rate limits going too high, but that's the same for any op amp with a slew rate of 0.5v/us.Your gain of only 1 resulted in lots of negative feedback and your frequency of 10kHz was maybe causing your opamp to attenuate crossover frequencies.
As per AG's observations, MrAl could you test the amp with a plus and minus supply with the load to common (midpoint of the supplies) or connected to the midpoint of two 2kΩ resistors in series connected from the V+ to ground, since that will increase the chance of observing crossover distortion?
I can see how using a single supply with a single resistor to ground minimizes that type of distortion.
I know the LM358. The LM358 is a friend of mine. I started designing with it the year it came out. But I'm with ag on this one. It is the greatest 2-wire intercom part in the world because it can survive almost anything up to a direct lightning strike, and a mile of cable across a golf course picks up a lot of stuff. But a guitar amp is almost as limited a set of requirements as a voltage follower bench test. For real audio, like a phono preamp or an active filter, it falls apart very quickly because of its limited GBW. The output stage bias trick cannot compensate for its inherent internal non-linearities caused by its low-gain PNPs, or its high input noise caused by its low input stage design current. Hell of a part, but an audio part only in a very restricted sense.
ak
Maybe the MC358 was used in geetar amplifiers because they want all the distortion as they can get. It was designed for low power so the bias current on the output transistors was so low that they produce crossover distortion since they operate in class-B instead of class-AB. I think it is wrong to force an output transistor to use a very high current continuously in class-A.
I use MC33172 dual low power opamps for portable low power supply voltage and current audio applications since they have the same input common-mode voltage range all the way down to 0V, lower power supply current and the same low power supply voltage as the LM358 but they have no crossover distortion and work well up to 35kHz.
I also bought some solder paste and it was expensive enough that i wont let it sit around forever without using it
I'm afraid so. Except for repair and building of legacy devices, and hobbyists, no one uses DIP packages anymore, so the volume is too small for manufacturers to economically keep building devices in that package style..............
Maybe DIP packages are going the way of the vacuum tube
Many ICs are made today in a "bumps on bottom" case that needs to be soldered in an oven I guess.
I'm afraid so. Except for repair and building of legacy devices, and hobbyists, no one uses DIP packages anymore, so the volume is too small for manufacturers to economically keep building devices in that package style.
Because of large inventories many old devices will still be around for years in DIP packages, but no new devices will be.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?