On Thu, 16 Mar 2006 11:50:29 GMT, Ignoramus2206
wrote:

On Thu, 16 Mar 2006 01:00:42 -0600, Don Foreman wrote:
On Thu, 16 Mar 2006 05:28:28 GMT, Ignoramus26498
wrote:

On Wed, 15 Mar 2006 20:41:57 -0600, Don Foreman wrote:
Does anyone own a similar power supply? I could not properly switch it
to constant current mode.

i

There is no switch.

Set the voltage to the maximum that is acceptable for your
application. Turn the current knob all the way CCW. Then turn off
the supply and connect the load. When you turn the supply back on,
advance the current knob until current reaches the desired level.

Thanks Don. Worked great, with a resistor. I set current with the
resistor in the circuit, then shorted outputs, and the current did not
change but voltage dropped to almost zero.

So, I think, this supply is quite suitable for tasks such as plating
small objects.

I appreciate your advice, it helped.

i

Da nada.

Yes, that supply should work nicely for plating and anodizing small
objects. Matter of fact, Caswell Plating sells Mastech supplies for
that use. The integral meters are a nice feature. I don't know how
well the Mastech supplies regulate current, but plating and anodizing
aren't that fussy.

The numbers cited in ebay auctions for new mastech supplies are very
impressive. Check this auction: 7599501997:

#

Two level of control for both current and voltage outputs: coarse and
fine for ease of use
# Adjustable outputs: 0-30V and 0-5A
# Input voltage: 110V AC and 220V AC switchable
# Line regulation: CV = 0.01% + 1 mV, CC = 0.2% + 1 mA
# Load Regulation: CV = 0.01% + 3mV, CC = 0.2% + 3 mA
# Ripple noise: CV = 0.5 mV RMS, CC = 3 mA RMS
# Protection: constant current and short-circuit protection
# LCD reading accuracy: +/-1% for voltage and +/-2% for current
# Environment: 0-40C, relative humidity 90%
# Size: 11.5" x 6.5" x 5.5"
# Weight: 13 lbs

I am not sure if I should believe these numbers, but as you said,
plating does not require that sort of precision.

It's quite easy to design a linearly-regulated supply with those
specs. You won't see that level of performance on the bench, though.
Example: just 300 micro-ohms of contact resistance at each connection
will produce more than 3 mV of drop at 5 amps. Banana jacks aren't
nearly that good. (Not that it matters.....)

Constant current is definitely the way to go because current is the
relevant parameter in these processes. Figure your surface area, dial
in the appropriate current, look at your watch and go do something
else while things progress.

Yes... I will be checking out the easiest process to start off with.

i

Zinc, copper and nickle are all pretty easy. Zinc is probably easiest
but none of them are difficult. Chrome is fussy, takes a LOT of
current, and the chemicals are very nasty. I don't mess with chrome.