Bromine - 5-4-2007 at 13:09
I have found two power supplys at low cost. One has 40V and 5A second have 20A and 15V, both have regulated voltage. Which one would be more useful in
experiments in chemistry.
chemrox - 5-4-2007 at 22:34
I found a variac at Fry's for $60. Very nice unit with a voltmeter on it. 10-120 vac 15 amp
Bromine - 6-4-2007 at 04:16
AC wouldn be much use for electrolysis and many other experiments.
indigofuzzy - 6-4-2007 at 20:57
AC could be rectified into DC.
As for which supply is more useful, it depends on what you're doing. But, most experiments in electrochemistry seem to use much lower (e.g. 1-7 volts)
voltages than either of your supplies.
kaviaari - 7-4-2007 at 01:10
In normal electrolysis the current is somewhat more important than high voltage. So the professional versions have low voltage but high current. This
is because the Faraday's law of electrolysis. It says that the total electric charge that passed through the solution is I*t. So the higher the
current the less time is needed to get the desired product. Most of the reactions happen easily when the voltage is over say 6V. I personally use a
12V car battery charger with the maximum current of about 6A and it has been enought for everything that I have done this far.
If you have a variac pushing out say 40V and the circuit is sucking the total of 12A you are going to need one big diode bridge and it will heat up a
lot. After the bridge you would also need a large capasitor to filter all kind of impurities in the current. Not to mention possible regulators etc.
I would go with the 15V and 20A one.
[Edited on 7-4-2007 by kaviaari]