Variable potassium chlorate power supply

[kilnj69]

Just spent the last 2-3days "(researching/buying components) building" my first potassium chlorate power supply. The drawing is not finished yet, just thought I’d like to share and welcome your advice during this build . Plus I have to wait for the parts to arrive before I can ACTUALLY build it .

So plenty of time to redesign/modify the plan while I wait. It is going to be built off of a old 250w ATX psu, and will be hacked to be fully regulated/variable by modifying the PWM signal to the KA7500B from this website (http://boginjr.com/electronics/lv/atx-mod/).

So it should be able to supply ~4.8-15V at MAX 5V - 22A and 12V - 9A

As I’m only looking for around 10A MAX at 5-6V so I should be in good shape.

FEATURES are as follows

1 x 14.5mm (.56") Blue LED Amp meter 0 - 9.99A

1 x 14.5mm (.56") Red LED Volt meter 0 - 99.9V

1x Blue LED 16mm hole 18mm OD push button switch

1x 25mm x 16mm Aviation Grade Aluminum Knob

2x 4mm binding posts

More to come soon.................

 

Justin

chlorate psu 1.bmp

chlorate psu 2.bmp

chlorate psu 3.bmp

chlorate psu 4.bmp

[kilnj69]

Edited February 11, 2013 by kilnj69

[50AE]

Haha, you're making it too fancy in my opinion. Just joking, but keep in mind that if it's near the cell, the later will leak gases and salts might leach out of it. If it's pH regulated it will leak chlorine which will attack metals nearby. So your new nice looking power supply will look like s**** in a few months and you will wonder why. The current you want is low though, so you might get away using long thick cables.

 

For my chlorate cell, I will try building a very high current, probably MOT with big rectifier diodes and a simple PI filter. Current value will be determined by the cable thickness and PI filter resistor or choke.

[Arthur]

Sorry but a properly designed switch mode psu will have the output volts and current and ripple sorted out and the input power factor compensation sorted out, all of which matter a lot.. Volts ripple is what can kill electrodes quickly -especially Pt electrodes for perc.

 

If you can minimally hack an ATX psu then you should have all this done for you.

[50AE]

Sorry but a properly designed switch mode psu will have the output volts and current and ripple sorted out and the input power factor compensation sorted out, all of which matter a lot.. Volts ripple is what can kill electrodes quickly -especially Pt electrodes for perc.

 

If you can minimally hack an ATX psu then you should have all this done for you.

 

Did I say something against switch mode power supplies? By saying "fancy", I ment the box, indicators and stuff.

[kilnj69]

Haha, you're making it too fancy in my opinion. Just joking, but keep in mind that if it's near the cell, the later will leak gases and salts might leach out of it. If it's pH regulated it will leak chlorine which will attack metals nearby. So your new nice looking power supply will look like s**** in a few months and you will wonder why. The current you want is low though, so you might get away using long thick cables.

Thanks Arthur and 50AE, I just received some parts for this power supply in the mail today (Will upload some pictures soon, so happy ). As Arthur mentioned with the ATX psu the features are excellent. I.e. perfect dc voltage with no ripple, overload protection, efficiency ect ect. As I will use this as a "lab/hobby power supply" (when not making chlorate) It's multifunctional and I like all the bells and whistles .

As you were concerned 50AE. I'm going to be using 12AWG 1 meter long silicone lipo wire to reduce resistance and carry the amps between the PSU and CELL. I don't want to get in to the whole setup here in the Electronics area just wanted to talk about the electronics (but with electrolysis I guess it's becomes hand in hand). I'm going to use a Mixed Metal Oxide (iridium-ruthenium) on expanded titanium substrate for the anode and titanium plate/sheet as the cathode/s.

I was just thinking that with the anode I've got, with a current density of around 200mA~300mA per square cm. I might like to run it at about 19A (~90% of the capacity of the PSU) I just bought a 0-20A blue led Amp meter. But as I’m in to quality not quantity of the finished product (500g-1kg). Sustainability of a continuously / permanently running cell is not of importance. (If I run out... I'll make some more ).

I've thought many times after researching/finding/designing/buying parts and doing more research....... why am I doing all this just to make some chlorate . I could just use the atx psu as is unmodified and leave it at that with out spending any money or time.

But I guess I want to try something no-one else has before, or maybe I just want to..........build something (Variable PSU)/make something (chlorate)........... And at the end of the day I can say, I can do that.

Justin

[kilnj69]

I have received all the parts, but am yet to build this properly. I could not wait to make some chlorate, so I used the PSU as is and got excelent results (about 89% effiency................. I know unbilevable ). I have tried to figure out why but i'm at a loss. ~900ml of solution at 350g/litre KCL running at ~4Amps for 65.5 hours running ~62 degrees celsius, yeilded 178G of kclo3 here is the graph from day one

NOTE: At 5:30pm I changed the water in the cooling bucket and the cell tempreature droped to aroung 40 degrees celsius.

 

I should get around to building the finished variable PSU soon.

 

Justin

[TomasBrod]

I was going to start a new thread, thankfully I noticed this one seconds before disaster.

This modification is moderately easy, with basic electronics knowledge and some soldering skills. You do not even need to buy the parts.
The main thing is to modify voltage feedback in the power supply. TL494 or compatible based units have feedback directly on pin no.1 of the chip. I basically removed the original voltage divider and replaced it with potentiometer and few resistors. Then I disconnected the other (+12V and -12V) outputs at output filter coil.

 

I put together an article on my personal website. There are some tips and link collection to other useful articles.

 

I managed to get output regulated between 2.5V up to 12V. Funny is, If I turn down the voltage quickly it shuts down, if I go slow it's OK.

My unit is rated 200W and I am yet to reach it's current limits.

[SeaMonkey]

The main thing is to modify voltage feedback in the power supply. TL494 or

compatible based units have feedback directly on pin no.1 of the chip. I

basically removed the original voltage divider and replaced it with

potentiometer and few resistors. Then I disconnected the other

(+12V and -12V) outputs at output filter coil.

...

If I turn down the voltage quickly it shuts down, if I go slow it's OK.

 

 

 

TomasBrod,

 

Excellent idea. Old Computer Power Supplies can be turned

into something very, very useful.