llplutot@hotmail.com wrote:
Quote:
Hey,
does anybody know how you can create a constant cathodic voltage (+/- 0
mV SHE) or a constant current ranging from 1 up to 200 mA. The electron
supply should not vary too much. I know a potentiostat can do the job,
but it's too expensive. I assume that the high cost for a potentiostat
is because it's very precise. Do there exist cheaper systems which can
do either one of the jobs (or the two) with an accuracy (standard
deviation) of +/- 5 mV (for constant potential) or +/- 0,5 mA (for
constant current)?
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Sure. Someone wanted to fly a potentiostat in a satellite experiment,
and got the Nijmegen (now Radboud) University to build them a
potentiostat on a printed circuit board. It didn't have any heavy
expensive poteniometers, because it was a single purpose device.
In order to make a fairly trivial job more interesting, I made the
design more or less indestructible - you could put 240V AC across any
of the inputs and they wouldn't blow up - and it still wasn't all that
expensive. The bare printed circuit board was the most expensive
component.
Commercial potentiostats are expensive largely because the market is
tiny, and every machine has to make an enormous profit to keep the
manufactueres in business. It pays to build them like tanks and fit
them with best and biggest potentiometers money can buy, because the
extra cost doesn't make much difference to price to the customer, and
the extra quality can squeeze out cheaper-looking competition.
E-mail me with more detail about your application
(billDOTslomanATieeePOINTorg), and I'll see if I can find the circuit
diagram and work out a way of sending you a copy.
-----------
Bill Sloman, Nijmegen
Constant current - constant voltage
Linear Mode
