[time-nuts] The "NAKED" 5065A optical unit

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Feb 20 04:30:54 EST 2018

In message <AABPJY7PFAJKDQYS at smtpout01.dca.untd.com>, cdelect at juno.com writes:

>Here is a PIX of the optical unit from a 5065A totally removed from the
>shield assembly.


>Left to right:
>Lamp assy
>lamp oven cylinder
>lamp reflector/convection block/diffuser
>Rb85 filter cell

It looks like there is a square filter of some kind
between the reflector and the filter cell ?

I've been thinking a little bit more about power for the lamp assembly.

Since I have the lamp on the bench-supply I am going to plot lamp
voltage vs. photo-I because it looks like a threshold rather than
a linear relationship.

If that is the case, I think it will make sense to give the lamp
its own adjustable voltage regulator (LM317), so the power can be
reduced to what is optimal/necessary without having to take the
lamp apart and change a resistor.

A 1R resistor between the 22-30V supply and the LM317 will make it
easy to monitor lamp current, and a 300mA short-circuit protection
is a nice bonus.

If need be, the regulator could start out at 20V and drop to something
lower in a matter of minutes.

Actually, now that I think about it, I should try to measure if it
is gives better stability if I drive the lamp with constant current,
constant power, constant voltage or constant photo-I...

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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