Blown digital VMs on rpc....
 

Brian Lawson wrote:

On Fri, 30 Oct 2009 00:33:02 -0400, "Existential Angst"
wrote:

SNIP
This is going to prove to be an effing effort way disproportionate to what
it "should" be. Mebbe I'll dig up more wallwarts (hopefully 6), and see if
they supply sufficient isolation. goodgawd....

Hey Pv'd,

And put a load across the "battery supply" (the output) of each of the
new wallwart outputs to keep them slightly loaded and the voltage
somewhere near the 9VDC the meters want. I've tried a bit of what you
were attempting with some other stuff, and find that the "DC" is
really ****ty, so much so that they won't for instance trying to run a
small portable radio when the "9VDC" wallwart output is strapped in
place of the batteries, or even when strapped across the batteries. 60
cycle hum like crazy. I should have put the scope on, but I'm both
busy and lazy. You should though!!! VBG


Get some 9.1 volt Zener diodes, 1 k resistors and 100 uF 16 volt
electrolytics. Put the zener and electrolytic across the meter's power
input, and put the 1 k resistor between the positive terminals. Then
connect the negatives. This will regulate & filter the power for the
meter.


Have fun. I've had three panel meters sitting ready to mount in my
RPC box for nearly five years now, but not taken (or had) the time to
fiddle with doing it. Maybe I will, now that you mention the voltage
discrepancies you saw on yours. 2 lathes, Bridgeport, and surface
grinder all work OK as it is, but something blew something in the CNC
lathe when I tried it with the RPC. Stuff for another day !!

Take care.

Brian Lawson,
Bothwell, Ontario.


--
The movie 'Deliverance' isn't a documentary!