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

Bob kb8tq kb8tq at n1k.org
Tue May 16 18:12:30 EDT 2017


If you approach this as “restoring a classic car”, then you repair the beast. From a practical standpoint, looking at the 
schematic and what’s in the divider setup ….. it looks like a < $2 PIC  or ($3 STM32 board ) would replace almost 
everything there. That’s not quite accurate, but it’s pretty close. Getting it all to work would take a bit of effort. On the 
other hand somebody may have a great big pile of modules running around. Replacement may be cheaper / easier than you think. 


> On May 16, 2017, at 4:33 PM, Ulf Kylenfall via time-nuts <time-nuts at febo.com> wrote:
> Starting to trouble-shoot some of the 5065A circuitryI saw that the (mechanical) clock drive flipflop IC1of the digital divider ass:y A16 is behaving very strange.
> All of the voltage regulator circuitry in this ass:y is working,providing 4.2V and so on, but IC1 and the two transistorsQ11 and Q12 exhibits a strange behavior.
> When IC1 is driven by a 1PPS squarewave of 0...4.2Vthe outputs of the transistors goes from either 0...4.2VOR 4.2...13V OR 0...13V in a random pattern.I can see this also at the bases of the transistors.The 13.3V is stable
> 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?
> (Just want to know if I should scrap the Option 01 and 03alltogether)
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