[time-nuts] Re: HP5061 offline management.

[paul swed]

Hi Charles thank you for your response.
The resistor is not hot at all. 81.6 degrees.
Its 9 ma. for the inverter. The rest of the power is simply the switcher
losses. The .31 watts is the 120 vac consumption not the 3500V inverter.
I actually use 2 X 220 ohm resistors in series as thats what I had but it
could be 470. Its not critical.
Regards
Paul

On Thu, Aug 5, 2021 at 6:51 PM Charles Steinmetz <csteinmetz at yandex.com>
wrote:

> paul wrote:
>
> > Leave just the 3500V supply run. Disconnect it from the internal power
> add
> > a resistor and cap powered by a external switching wallwort in the 1 watt
> > range. Brand new meanwell  units are $11. These are medical grade not
> that
> > its required. The resistor is about 470 ohms a 1/4 watt. Dropping 24V to
> > 19V. Use a 470 uf cap on the side of the resistor connected to the 3500V
> > supply. Ground the negative to the chassis so the I pump meter works.
>
> I may have misunderstood what you are doing, but a 470 ohm resistor
> dropping 19v to 24v will draw from 40 to 51mA, and will dissipate from
> 0.75W to nearly 1.25W.
>
> If this is the real operating condition, it's not a happy place for a
> 1/4 watt resistor.  You'd really want a 2W or greater resistor there,
> with some good ventilation around it.
>
> Best regards,
>
> Charles
>
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