[time-nuts] HP 5275A

Howard Davidson hld42 at att.net
Sun Nov 6 21:46:00 EST 2016

The real hack in the 5245 Nixie tube decoder is that the neon lamps were 
the memory element.


On 11/6/2016 2:15 PM, paul swed wrote:
> Don't know what to say on the transistor. It may have been actually made
> that way. They did lots of things back then. Yes familiar with the bcd
> decoder its used in the 5245 class counters also. I think someone was doing
> some funny stuff at lunch time to come up with that. It was the 60's after
> all.
> How about some pix of a 9815 calc. That would be pretty neat.
> On really old stuff if you can't find the part needed its pretty easy to
> replace the whole function with modern answers. I know it sort of breaks
> the original mode but for me at least its a case of getting it going.
> Regards
> Paul
> On Sun, Nov 6, 2016 at 1:59 PM, Adrian Godwin <artgodwin at gmail.com> wrote:
>> Slightly off-topic, as this is a general repair question. But it's a TIC.
>> I'm repairing a 5275A timer (all-discreet count logic to 100MHz, neon bulb
>> display, a most amazing bcd to decimal decoder made from neons and LDRs,
>> 1-2-2-4 decade counters ..) and the current problem is a 2n1038-2 germanium
>> T05 transistor in the power supply.
>> It's mounted in an aluminium bush which is then isolated from the chassis.
>> I don't think the bush is also a collet but I can't see how to remove the
>> transistor. It resists ungentle pushing .. should I push it with a hammer ?
>> Or is there a kinder way ?
>> (I'm hoping to eventually put this into a system with a 101A oscillator and
>> a 9815A calculator to measure the ADEV of a Boule electric pendulum clock).
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Howard L. Davidson
hld42 at att.net

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