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
I am wondering if anyone knows of a replacement that has the same
pin-outs of the LM387?
73 Markus VE7CA email@example.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.
[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.
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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 <firstname.lastname@example.org> wrote:
> The LM387 was a popular low noise dual 8 pin op-amp that was usedI 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.
2301 2008-10-20 13:10:48 bobtbobbo Re: LM387 >This link lists some possible substitutes you might want to look into:
> [Non-text portions of this message have been removed]
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.
2304 2008-10-21 21:36:01 ve7ca2 Re: LM387