[time-nuts] HP Z3801A Communications

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon May 19 00:33:31 EDT 2008

Charles Watkins wrote:
> Hi Dick, I've been silently enjoying all the comments that Time-Nuts Digest
> has had to offer for some time now, and have been too timid to respond (or
> simply not smart enough).  I do have a solution if you do not want to make
> the RS232 conversion on the Z3801A.  Originally I made a 422 to 232
> converter using a free sample chip from Maxim.  I believe it was the MAX232.
> It worked fine, and I still have it.  I mounted all the required surface
> mount components "dead bug" style on a small piece of perf board and mounted
> that within a DB-25 back shell.  The only drawback with the circuit was that
> I had to provide an external 5 volt supply and since I did not want to
> intrude into the PC, I used an external bench power supply.  I eventually
> bit the bullet, and made the modification inside the 3801.  Glad I did, it's
> much simpler now and unless you need the long line length that RS-422 can
> handle, the 232 mod is well worth it.  If you want further info on the
> MAX232 method, I can take pictures of the one I built and dig up the
> schematic I used.  However, it can be found on the web, I just can't locate
> the links right this minute.
> Good luck,
> Charles
Try a MAX3162.
It has RS232 derives and receivers as well as an RS485 driver and receiver.

The MAX232 contains TTL/CMOS to RS232 drivers and RS232 to TTL/CMOS 


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