12v Cascade ( Powder Coating )

Thread Starter

Roger60

Joined Feb 29, 2020
34
Hi all,
I am new to AAC and really envious of the people's knowledge on here.
Many years ago my knowledge began with the old CRT tv but unfortunately my life took a different path.

If you don't mind me asking.
It is with reference to a Powder Coating controller.
My understanding is a low voltage oscillator with high frequency negative output, which is then sent to a voltage multiplier ( cascade unit.)
Please correct me if I am wrong as my current unit has failed so if anyone could give me a basic insight that would be great.
My unit is a sealed system so is not meant to be played with.
I would really appreciate any input or advice.
Many thanks in advance.
Kindest Regards.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Thank you for the reply.
It is a resin sealed unit so i know it's is irreparable.
Running by a switching relay for the negative oscillation which then goes to a HV unit (sealed).
Cheap and Chinese
I am thinking if it's viable to make a basic system which could be run by electronics rather than a relay.
Any advice would be very much appreciated.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Thank you Shortbus,
I purchased an after market gun and a cascade unit a few weeks earlier as I knew the one I had would not last.
Since my original unit gave up the ghost, I took it apart and saw the internals were nothing like I had expected.
The cascade unit is powered by 12v and that is as much as I know about it.
Attached are pictures of said items.Screenshot_20200303-001316.jpg
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Sorry I posted before finishing.
I have looked at the link's you put up ( very much appreciated ) and the 555 timer has been mentioned.
In your opinion would you go down this route?
Unfortunately i only had a few months working with tv's many years ago. But was well aware of the HV line output transformer.
All advice and help is very much appreciated ;)
 

MisterBill2

Joined Jan 23, 2018
9,779
Thank you for the reply.
It is a resin sealed unit so i know it's is irreparable.
Running by a switching relay for the negative oscillation which then goes to a HV unit (sealed).
Cheap and Chinese
I am thinking if it's viable to make a basic system which could be run by electronics rather than a relay.
Any advice would be very much appreciated.
Here is a guess, which is that if not all of it is sealed in some resin material, it may be that a non-sealed part has failed and could be replaced. It may also be that something easily available will remove the resin material. 25 years ago we discovered that soaking encased engine computers in unleaded gasoline in a closed bucket for a week allowed the stuff to be removed. That was cheap back then, now gas costs a lot more. And I don't have a source of sealable steel buckets any more.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Lol MrBill.
Gas is expensive...the picture shown is a new unused cascade. My old system is broken and different to the item above.
Sorry for confusion.
That new cascade is what I would like to use and hopefully get up and running again.
The old unit has a relay which triggers the HV output which is also encased.
Will take a picture and post up.
 

MisterBill2

Joined Jan 23, 2018
9,779
An adequately sized relay is good for thousands of operations, and usually simple to replace when they fail. Electronic control when adequately sized and installed, can also work very well. But selecting the switching transistor without knowing the voltage or the current or the transistor drive available is a big challenge. In addition, the switching transistor will probably need a heat sink.
 

shortbus

Joined Sep 30, 2009
8,951
I have looked at the link's you put up ( very much appreciated ) and the 555 timer has been mentioned.
In your opinion would you go down this route?
It depends. Are you using this to make money? Then I would look into buying one, I worked with a guy who did powder coating on the side and he had a professional sized one, but don't know the brand name. A timer based one is going to be more involved than a cascade type.

Your "cascade" is really called a Cockcroft-Walton voltage multiplier - https://en.wikipedia.org/wiki/Cockcroft–Walton_generator They are pretty reliable if the correct components are used, components with values correct for the voltages, which most of the hobby machines don't do. They are made for a guy doing small parts and not much more.

I think if I was to do this I would start with a higher DC voltage than 12V. This would allow the cascade to have fewer steps. I do know that the guy from works machine wasn't like the little Harbor Freight ones it was built heavier using better components. Here is a good place to get components for something like this -
http://www.surplussales.com/
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Thank you.
I really appreciate what you have said and understand where you are coming from ( I think ) lol.
All the reading into the pro units state around a 15- 30KHz frequency with variable micro amps output.
What would be the max switching rate of a relay?
I only have a basic understanding of circuits and do really need all the help I can get.
This is why the more I read the more confused I get.
If someone can enlighten me I couldn't thank you guys enough.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Sorry Shortbus,
Just saw your comments.
All I know is it is a 12v supply voltage for that cascade.
I have just started out with a cheap unit and 3/4 through doing my motorcycle.
Expecting to build an all singing and dancing machine is not may aim so do appreciate everyone's effort.
Just something basic but reliable, unlike the unit I did have lol.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
The Eastwood does look ok but it's not available over here.
After more and more reading I came across a circuit which consisted of two transistors which in turn switches a misfit.
It is controlled buy a 555 ic. Would someone please tell me if this circuit could be used to control the above cascade please.Screenshot_20200303-162543.jpg
 

shortbus

Joined Sep 30, 2009
8,951
The Eastwood does look ok but it's not available over here.
Where is, "over here"?

With just a quick look that should do it, with a few changes. But I'd like to see the whole article it came from before commenting more.

I did some looking my self last evening for you and found a similar one, but one that the guy was using to make his own powder coater from scratch including the gun. He used a flyback transformer from a CRT computer monitor to make the high voltage instead of a cascade, which should in reality work as good or better. http://thegreatgeekery.blogspot.com/2010/07/powder-coating.html His "updates" links show the circuits.

I thought your cascade was the problem in what you already have? Thought you said it was covered in epoxy and couldn't be repaired?
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Sorry Shortbus, I am computer illiterate, I thought you knew where I was from lol.(UK)
I have confused all as I didn't put up picture of my broken unit.
The cascade is what I purchased a while back and was only interested in using it because it was here with a new gun.
That's the reason I didn't go for the flyback transformer and because there would only be low voltage up to the gun.
If you think a fly back would be better then you are the master and I am the student.
The unit that's broken is sealed so dead.
The cascade in the picture is the new one.
I have to thank you for all your time and effort you've put into this. It's really appreciated.
Shall source the link and TRY and put it up now.
 
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