EMRFD Message Archive 2292

Message Date From Subject
2292 2008-10-20 10:37:34 ve7ca2 LM387
The LM387 was a popular low noise dual 8 pin op-amp that was used
widely for low noise amplifiers in a number designs like the R1 DC
receiver by KK7P. It is no longer in production and I have not been
able to find a replacement for one that failed in my homebrew 6 meter
DC transceiver.

I am wondering if anyone knows of a replacement that has the same
pin-outs of the LM387?

73 Markus VE7CA mkve7ca@shelbrook.com
2293 2008-10-20 11:51:49 Nick Kennedy Re: LM387
You might check Futurlec, they seem to maintain some out of production

Regarding the LM387, it couldn't be directly replaced by a general purpose
op-amp because it has internal biasing to the (+) input of about 1.35 VDC,
or two diode drops. If you did find a suitable op-amp, you might make it
look like an LM387 by adding two diodes to ground at the + pin and feeding
it from Vcc through a 100k or so resistor. (check the data sheet for the
actual resistor value). That's how I model it in LTSpice.

73--Nick, WA5BDU

[Non-text portions of this message have been removed]
2294 2008-10-20 12:12:25 Pat Bunn Re: LM387
I have two that I bought on EBAY several months ago. When I saw that they were rare - I did not use it in my amp.

Email me if you need one.

Pat Bunn

----- Original Message -----
2295 2008-10-20 12:12:28 bobtbobbo Re: LM387
2298 2008-10-20 12:12:59 michael taylor Re: LM387
On 10/20/08, ve7ca2 <mkve7ca@gmail.com> wrote:
> The LM387 was a popular low noise dual 8 pin op-amp that was used

I don't know of any replacement parts, but the LM387N (plastic DIP
package) are apparently available from Futurlec (Thailand or
Philippines) and Unicorn Electronics (PA, USA).


I haven't looked at the datasheet / pinout to see if a newer low-noise
8-pin dual op-amp might be a suitable substitution or not.

-Michael, VE3TIX
2301 2008-10-20 13:10:48 bobtbobbo Re: LM387
> [Non-text portions of this message have been removed]
This link lists some possible substitutes you might want to look into:


Bob, K1AO
2302 2008-10-20 20:10:06 Rick Re: LM387
Hi Marcus,

The Signetics/Phillips NE542 has the same functionality and pinout, and I have used them
both in the R1 circuit. The LM387/NE542 were a wonderful part back in the day, but I
designed them out of my later circuits when garden variety dual op amps like the dual
5532 surpassed their performance. I still use them occasionally when I want to fire up an
original R1 board.

It looks like you have an offer of a replacement from the group.

Also, I am flattered to be confused with KK7P--that is my friend Lyle's call. He's well
known for a number of contributions to the art, often involving digital signal processing.

Best Regards,

Rick KK7B

, and
2304 2008-10-21 21:36:01 ve7ca2 Re: LM387