Woody,
That’s impressive. Your example shows how the DROK
compensates for the voltage IT IS BEING SUPPLIED, and “boosts” its conversion
level to maintain an OUTPUT set point voltage (under or over) ... based on its
own INPUT. This will work great for a battery supply, which gradually loses
power. However, if the DROK supply is from say an AC/DC supply, and the
household power dips a bit – for reasons I stated previously – I would assume
that a well regulated AC/DC supply would likewise maintain voltage for the DROK,
in this chain.
My “feedback loop” was more about voltage drop in the
resistance of wires from the DROK to the telescope stuff. Would the DROK still
provide a steady 12 vdc output during load changes – CCD cooling variable load,
or mount slews, where more amps are drawn and some voltage is lost to the cable
resistance?
The DROK maintains its own output steady, even as it is
supplied by weak or spikey power. But without a feedback line, the DROK
wouldn’t know about raising its preset 12 vdc slightly, to account for the
equipment load it is supplying. Then again, DC cables are 2-wire, so a feedback
compensation would require a third wire, which means special 3-wire cable if we
wanted compensated output.
Anyway, it is probably not that much of a problem,
unless the DROK is driving an accessory at borderline voltage levels. If the
equipment loads the DROK output, so that a bit more is lost along the DC cable,
then the CCD might only be running with 11.5 VDC (even though the DROK is
putting out 12 vdc at its output terminals).
The DROK supplying reliably consistent 12.0 vdc to the
CCD depends somewhat on the cable length joining them, and the size of the load
variability. The DROK can provide “reliable power” BELOW a user set maximum
level, but not compensate for lost power actually delivered at the load.
I’ll leave it at that, since this is more of a
“theoretical” possibility.
Must say, based on its reasonable price and excellent user feedback,
the DROK is a really nice device for supplying varied levels of voltage to our
diverse accessories.
*****
One other thing came to mind, while viewing that “bulky”
oversized DROK case’s assembly video.
In the interests of saving scope space needed for DROK enclosures, for
say, TWO different voltage levels controlled by individual DROK’s - I was
wondering if it would be possible to “stack” two DROK boards inside the same
case.
Would be nice to have just one (switchable) DROK meter for both – using
something similar to the old PC’s (parallel port “printer sharing”) switch
for its two IDC cable connectors. But, I suspect the meter itself holds
dedicated parameters for just one DROK - thus not switchable. In such case, a
second DROK panel meter might still be attached to the back end, with
the fan(s) and output posts, relocated to the enclosure side
panel(s).
Joe
