12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Switching supply for electrolysis
Hey, would anyone be interested in buying kits or prebuilt power supplies for electrolysis? I'm thinking 0-5V, up to 50A (at any voltage), output
ripple probably good enough for your computer if you were that desperate.
I don't have a design on hand at the moment but it's really a pretty simple thing. Say 10 people wanted one, I could design and build them in a month
or two, plus little lead time for any additional units. I would guess cost in the $100 range.
Tim
|
|
|
starman
Hazard to Others
Posts: 318
Registered: 5-7-2008
Location: Western Australia
Member Is Offline
Mood: No Mood
|
|
@12AX7 Having looked into some laboratory DC supplies that seems a reasonable price range for that kind of constant amperage.I would definitely be
interested,although shipping to Australia would probably kill it for me price wise.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
What's shipping to .au usually run, I'm guessing a few bucks a pound? That's not too horrible. At least it isn't a linear supply with a laminated
iron transformer!
Tim
|
|
|
woelen
Super Administrator
Posts: 8013
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
I must give one word of warning with switching power supplies. They are very good for electrolysis purposes and of course for many low-voltage
electronics experiments, but they are VERY easily killed by HV-equipment. I killed two switching power supplies, simply by attaching a 12V --> 15
kV converter to it. The electrostatics, produced by this 15 kV converter simply kill the switching power supply.
This of course only is relevant if the power supply is used as a general purpose power supply for both low-voltage and high-voltage experimenting.
Another thing is that the supplied voltage probably should be somewhat higher. Some cells do not draw much current at 5 V. Maybe the usefulness can be
extended quite a lot if the maximum output voltage can go as high as 7 volts.
[Edited on 21-7-09 by woelen]
|
|
|
Polverone
Now celebrating 21 years of madness
|
Thread Split
21-7-2009 at 08:52 |
dann2
International Hazard
Posts: 1523
Registered: 31-1-2007
Member Is Offline
Mood: No Mood
|
|
Hello,
Don't want one myself even though I mess around alot with Chlorate/Perchlorate/Anodes etc. I am up to my eye-balls in power supplies. Another one and
'her indoors' would put me outdoors.
A specification that I would rather see (for Chlorate etc) would be something like:
An open circuit Voltage of 7 Volts and a current capability variable from 0 to 50 amps (ie. a constant current supply). Is that easily done with SM
stuff?
Going off topic for this thread I will give a quote from here
"For any power transformer, the maximum flux density is obtained when the transformer is idle"
Is this what the fracas was about.
Also size of power transformers is frequency related as you get smaller and lighter packages for same power as freqeuncy goes up.
Dann2
[Edited on 21-7-2009 by dann2]
|
|
|
Dr.3vil
Hazard to Self
Posts: 59
Registered: 27-7-2006
Location: Secret Underground Bunker
Member Is Offline
Mood: 4He + 8.7 MeV
|
|
Potentiostat
I have been thinking about a homebrew system for controlled potential/current electrochemical work. These devices would have far more value then just
a simple power supply. Even a simple unit with reasonable stability would open the doors for amateur work in electrochemistry, not to mention a wide
class of synthetic pathways to organic chemists. Like most scientific equipment, their price precludes them from the home lab.
http://en.wikipedia.org/wiki/Potentiostat
http://www.gamry.com/App_Notes/Potentiostat_Primer.htm
DR.3vil
- Paper chemistry works the first time every time -
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
The supply could have an operational input which would allow any generalized sort of control, constant voltage, constant current, potentiostatic, etc.
Such an input would also require some electronics knowledge to use properly.
On the other hand, I'm guessing most uses for a potentiostat would be much lower current, allowing one to simply use, for example, a power op-amp
(e.g. LM1875) to drive the cell. Add supply (a linear supply would be fine) and off you go. It would be good for whatever voltage you're using
(10-30V?) and a couple of amps. A discrete model could easily be built for many more amps. Matter of fact, I have the parts to make a +/-20V, 20A
bench supply... I need to build that some day. 
Tim
|
|
|
starman
Hazard to Others
Posts: 318
Registered: 5-7-2008
Location: Western Australia
Member Is Offline
Mood: No Mood
|
|
Constant current at greater than about 3V@50amp range would suit my purposes nicely.As long as shipping runs at under 50% of the unit cost you can put
me down for one.I like this kind of initiative on the forum,surprised we haven't seen a glassblower offering custom glass to order.
Should you proceed with this 12AX7 please U2U details.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
|
|
|
chromium
Hazard to Others
Posts: 284
Registered: 27-6-2005
Member Is Offline
Mood: reactive
|
|
I would not buy SMPS for lab use if its design is not well tested for reliability. Like woelen sayd switchmode PSU-s are sometimes very easy to kill.
Some years ago when i had access to computer power supplys with almost no cost i choose ones for lab use by short-circuiting all outputs in nearly
every possible combination several times. About one third or quarter of PSU types survived this mistreatment and no one of them has failed
afterwards. Some of those wich did not survive were killed by just one-time short from 5 or 12V to ground.
When all think alike, then no one is thinking. - Walter Lippmann
|
|
|
Swede
Hazard to Others
Posts: 491
Registered: 4-9-2008
Member Is Offline
Mood: No Mood
|
|
Fixed voltage supplies can be used, but after using a true variable supply, it is like comparing a Yugo with a Porsche. A true CC/CV supply is a joy.
I've used both switchers and linears for chlorate/perchlorate cells, and the switchers do work fine, at 1/5 the weight and lower cost too, but yes you
do need to know that they cannot be abused quite like a good linear supply can.
A 1 kw linear supply will probably weight 40 to 60 pounds. They are big, heavy, expensive, and getting harder to find at a decent price. If I was on
a budget, I wouldn't hesitate to go with a switching supply for the stuff we generally do.
If the kit can be set up variable voltage at a minimum, I think it'd do well.
|
|
|
densest
Hazard to Others
Posts: 359
Registered: 1-10-2005
Location: in the lehr
Member Is Offline
Mood: slowly warming to strain point
|
|
Mr. 12AX7's project overlaps with some stuff at my chaotic corner. I'm not trying to take over anything - it just happens I've got some parts which
might help  ...
I've got quite a number of Vicor BAT-MOD 0-56V 0-4.2A constant current/constant voltage DC-DC converter modules I'd be happy to sell for a very
reasonable amount each. They require: a nominal 300VDC input (250W per module)
a fuse per module
a heat sink definitely and a fan if not positioned to get good cooling
an input noise filter to protect the module from the mains and the mains from the switching noise generated by the module
an output filter to protect the module from the load and the general environment from switching noise.
0-5V (or so) DC control voltages in. It produces voltage outputs for current, and I think (IIRC), that they can be paralleled in
constant current mode. If there's interest, perhaps in collaboration with 12AX7, a circuit board to hold one of these could be made, also
containing:a universal input (100-250VAC 50-60Hz) PFC AC-DC chip/modulea fuseholderterminals to connect
everythinga couple of control potsprovisions for either analog or digital meters Of course, there's always the alternative of
attaching a USB module with 2 DACs and 3 ADCs for computer control, or a microcontroller for local programming.
Any thoughts?
Also, I've got two or three Vicor Mega-Pack 2KW universal input PFC power units which accept these modules on plug-in circuit boards, holding up to 7
boards, also accepting other Vicor modules for 5V, 12V, 15V, etc. etc. They're shoe-box sized and not too heavy (5Kg?) for shipping. If someone has
one of these, a Bat-Mod can be put on one of the carrier boards instead of one of the fixed output units.
[Edited on 23-8-2009 by densest]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
