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Andy, I deal with a lot of old circuitry. Mica caps going bad, as you stated, are VERY rare. It does not seem to be a DC problem as I am feeding in a square wave at 25kHz. I doubt over voltage has

I do not remember ever hearing of mica caps going bad.? I do not think they age, or fail except by over-voltage stress. But one hears about electrolytics (both Al and Ta) aging and/or going bad all

True Andy. I meant to refer to the LM108 in the app note. The circuit I have is using the LM118 though. Still looking for that LM121 model. The issue is that the circuit I have is not bench performing

Careful, there!? You have the wrong second-stage op-amp.? 118 ≠ 108. The application note shows the *LM108A* as the op-amp that is coupled with the LM121 preamp.? It is not a LM118A.? Those two

I think what you mean to say is that *TODAY's LM321* is not the same device! But originally the LM321 was the same as the original LM121.? Then at some later date, either NatSemi or Texas Instruments

Hi all, I'm working on a project that involves saturable transformer and when I try to model it in LTSpice, I can observe the saturation effects when there is sinusoidal voltage but I cannot really

Mike, that is the correct datasheet. The LM121 was mentioned in the 1994 NSC Application Handbook. I uploaded that ap note to the TEMP files as well (LM121 AN-79.pdf).

All, I just uploaded a LM121 data sheet to the temp folder. Mike

Strange, my yellowing copy of the 1980 edition has the LM121/221/321 on page 4-11. -- http://davesrocketworks.com David Schultz "The cheeper the crook, the gaudier the patter." - Sam Spade

Indeed; many web sites offering its data sheet do not in fact include LM121, only LM221 and LM321, which do not have two outputs. -- This email has been checked for viruses by AVG antivirus software.

The LM121 is shown as a preamplifier IC in the 1976 National Semiconductor Linear Data Book, but it's not listed in the 1980 edition.? I will look to see if I still have the 1976 data book or any

The old National Semi numbering system was LM1xx for Mil-temp devices, LM2xx for industrial temp, and LM3xx for commercial temp. Then the LMyx1 was for the single version, LMyx2 for dual and LMyx4 for

If you meant LM321, it is a single version of an LM324.

The LM121 has a differential output. Pinout is 1: output 2 2: IN- 3: IN+ 4: V- 5: balance 6: balance 7: V+ 8: output 1

All the models do not show the proper LM121 differential output configuration. Andy, you are correct about the LM121 being special. The old National Semi Apps Handbook has the LM121 and LM118 used as

It looks like the LM121/LM321 was a very ordinary 1 MHz GBP op-amp, but maybe with somewhat lower operating power (lower supply current).? It is capable of +/-16 V supplies, but optimized for 5 V

As I say, it's been too many years.? But I do not remember that the LM121 was anything like the LM118.? The latter was optimized for high slew rate and bandwidth, unusually high in its day. Andy

Remember that LM121, LM221, and LM321 are the same, just with different worst-case ratings. There is something that claims to be an LM321 SPICE model, here:

Derek, There is a PSPICE version on that list.? I use it all of the time in LTspice.

If it's a Tina model, it might be compatible with LTspice, but might need some tweaks. -- This email has been checked for viruses by AVG antivirus software. www.avg.com