[time-nuts] Re: HP z3816a DC power supply DIP switches

[paul swed]

As Ed stated Switchers feeding switchers can be problematic. What I found I
had to do was put a relay in series with a slight time delay. This allows
the primary switcher to come up and then gets slammed into the secondary
SPS. Could be a fet/transistor switch. So linear is preferable.
Regards
Paul
WB8TSL

On Tue, Mar 1, 2022 at 11:20 PM Dave ZL3FJ <2c39a at silverbears.nz> wrote:

> If its anything like the Z3815A then the supply should provide 24 to 48V DC
> at about 25W continuous, and
> be capable of providing around 40W for 10 minutes while starting. (this
> data is  from the unofficial manual for the  Z3815A that Murray Greenman,
> ZL1BPU, produced some years ago when a number of the Z3815A/GPSR units
> appeared on the surplus market down this way)
>  DaveB, NZ
>
> -----Original Message-----
> From: ed breya [mailto:eb at telight.com]
> Sent: Wednesday, March 02, 2022 16:39
> To: time-nuts at lists.febo.com
> Subject: [time-nuts] Re: HP z3816a DC power supply DIP switches
>
> Sam, I noticed in your last post that you're planning to use a printer type
> PS. It may work if you luck out, but I suspect that it won't have enough
> juice to get things up and running.
>
> If it's anything like the typical ones I've seen, it's a small SMPS brick,
> built for running ink-jet printers. These tend to be just heavy enough for
> their normal purpose, but not much beyond. Actually, most SMPSs don't work
> well for transient startup conditions like this. In this case, you have to
> charge the big filter cap, and take on the negative input R, and the high
> initial oven heater load. SMPSs tend to be very quick in protect-response,
> and likely will current limit, by going into immediate fold-back, tick
> (chirp), or trip (and manual reset) mode. You can of course, try it and see
> - it shouldn't hurt anything. If it immediately faults, you can try letting
> it do its own soft-start, by connecting the load first, then plugging the
> PS
> into the line.
>
> I think your best bet is to use a bench linear PS for experimenting - one
> with way more current capability than you apparently need. Then you can
> figure out how it all actually works before deciding on the long term
> solution.
>
> Ed
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