[time-nuts] HP 1820-0313 4.2V Logic (Flip-flop)

[Dave M]

Poul-Henning Kamp wrote:
> --------
> In message <1580810140.741428.1494966823210 at mail.yahoo.com>, Ulf
> Kylenfall via time-nut s writes:
>
>> That the 1820-0313 is unobtanium I can understand.Has anyone created
>> an equvalent based on discretesor is there a suitable SMD "single"
>> flip-flop like single gatesthat could be suitable?
>
> I did a divider board for the LED clock:
>
> http://phk.freebsd.dk/hacks/HP5065A/20160112_working_clock/index.html

The 1820-0313 is a Fairchild 931HC or Motorola MC931G DTL clocked flipflop.
I think if you toy with a TTL or CMOS JK-flipflop; it should work with no
issues.  The only caveat would be the 4.2V Vcc.  The DTL logic was spec'ed
to run at 5V, same as TTL, but don't know how TTL logic would work at 4.2V.
.
You might find a 3.3V flipflop and zener the 4.2V Vcc down to 3.3V and build
it all onto a small piece of perfboard.

I've attached a copy of the pertinent pages from my old Motorola databook
(1966 Motorola Semiconductor Handbook) directly to Poul.

Dave M