12v Cascade ( Powder Coating )

Thread Starter

Roger60

Joined Feb 29, 2020
34
Hi Both, It was a case of brain freeze yesterday.
MrBill, After discussing things with you, I now understand the relay is activated by the foot switch ( not for the oscillations ) of the circuit.
This is why my concerns were about a relay for oscillations because of the noise lol.
So you are saying it works on the principle of a transformer ratio and then a regulator?
You are correct in saying everything is inside the ( sealed black box ).
When I condemned the unit there were oscillating noises but no output voltage. It was extremely low.
 
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Thread Starter

Roger60

Joined Feb 29, 2020
34
Hi Shortbus, Reading and video's has been my life for quite a while now.
I can't even get the smilies to work lol.
The trigger is a micro switch which could control relay and or solenoid valve. If I went down the road of a Flyback, which I am swaying towards.
You are correct in saying about high voltages for the flat surfaces. But powder coating suffers from ( faraday cage effect).
Because the charged particles will take the easiest path ( flat surface ) the edges and hollows suffer, So variable voltage is good but also the variable current and air pressure, even though we would be dealing with micro amps output.
The other thing to deal with is the -negative voltage output. It will not work without the negative charge.
It is the electronics side of thing's I struggle getting my head around. Thanks to you guy's, I am slowly getting there.
Can't thank you people enough for dedicating your time to us apprentices.
 
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shortbus

Joined Sep 30, 2009
8,971
The trigger is a micro switch which could control relay and or solenoid valve. If I went down the road of a Flyback, which I am swaying towards.
If my unit ever dies, I would build one with the flyback. The modern CRT color TV flybacks have a DC output, making them perfect for this. Flybacks from a CRT TV are made to work for hours at a time so will live longer than the cascade, especially on big jobs.

All of the professional coater machines, or at least the ones I know about, use a flyback and not a cascade. For two reasons I can think of.
1.they are made for extended use
2.the guns will be less fatiguing to the operator, because the electronics are in a box or cabinet not in the gun.

Now days it's not just powder coating that uses this HV, standard spray painting in manufacturing uses it too. To save the cost of paint, it makes less over spray and better coverage.

Reading and video's has been my life for quite a while now.
I can't even get the smilies to work lol.
If that is in reference to posting links to your items, all you need to do is -
1. left click your mouse on the address bar of the page of the link.
2. right click and choose 'copy'
3. in your post, left click again and choose 'paste'

If that isn't what you meant don't be offended by me thinking it was and telling you how to do it.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
If my unit ever dies, I would build one with the flyback. The modern CRT color TV flybacks have a DC output, making them perfect for this. Flybacks from a CRT TV are made to work for hours at a time so will live longer than the cascade, especially on big jobs.

All of the professional coater machines, or at least the ones I know about, use a flyback and not a cascade. For two reasons I can think of.
1.they are made for extended use
2.the guns will be less fatiguing to the operator, because the electronics are in a box or cabinet not in the gun.

Now days it's not just powder coating that uses this HV, standard spray painting in manufacturing uses it too. To save the cost of paint, it makes less over spray and better coverage.



If that is in reference to posting links to your items, all you need to do is -
1. left click your mouse on the address bar of the page of the link.
2. right click and choose 'copy'
3. in your post, left click again and choose 'paste'

If that isn't what you meant don't be offended by me thinking it was and telling you how to do it.
I did say I was computer dumb lol
The tablet is different to computers but getting there.
I have bowed down to experience and ordered a flyback transformer, should be here tomorrow.
The circuit diagram I posted is nearly finished as most nights I am awake. It was said it could work with minor alterations.
Are you able to explain in minor detail what is needed to be done.
The two variables are in the post and the 4700μf cap.
Will put up pic if you wish.
Thank you.
 

MisterBill2

Joined Jan 23, 2018
9,886
The trigger operated microswitch can work with either type of high voltage source, and with any solenoid air valve. There are lots of circuits for flyback transformer based high voltage supplies, but do you have enough experience to build one from just a circuit schematic? They are not terribly complex, but they do demand that certain portions be "just so." Of course, there are a lot of flyback supplies remaining in CRT computer monitors. That could be a really cheap source of all the parts.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Hi MrBill,
I believe I can follow circuit diagrams (providing) I know the component values etc
As I have almost completed the circuit schematics I posted earlier.
I'm sure you kind gentlemen will point me in the right direction lol.
Just kidding.
 

MisterBill2

Joined Jan 23, 2018
9,886
Hi MrBill,
I believe I can follow circuit diagrams (providing) I know the component values etc
As I have almost completed the circuit schematics I posted earlier.
I'm sure you kind gentlemen will point me in the right direction lol.
Just kidding.
There are two sites that I have seen circuits for flyback high voltage supplies on, but neither of the sites provides the associated text or much in the line of parts listings. Probably on this site, some place, there is somebody with the information that you need. One caution is that if the application really needs such a high negative supply voltage, the rectifiers that are often a part of flyback transformer assemblies may not be able to handle that high a voltage without breakdown. For a large CRT color set I have seen 27kV, but that is about the most I have seen. Projection TVs of longer ago may have had higher voltages but I am not familiar with them at all.
A different option could be a voltage multiplier circuit fed by a transformer used for neon signs, and other gas discharge tube signage. I had one of those rated for 360 watts output, 12,000 volts at 30 mA. Rather dangerous, though, that much voltage with that much current behind it. Also, it weighed about 12 pounds.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
The pro units do go up to 100kV, but I'm not greedy lol. The only other thing is to make a cascade/ Cockcroft Walton as you are aware. Diode/capacitor circuit. Ideally it needs to be 50kV to be worth doing. Through all the reading I've seen it mentioned (as voltage goes up the current goes down). There would have to be many stages to even reach 50kV ?
I have seen two FB Transformers in parallel.
There are a few diy powder coating systems using FB Transformers but would have to find again.
12lbs is not much if it's in a control box lol.
The FBT and switching isn't the problem it's the negative voltage output.
 

MisterBill2

Joined Jan 23, 2018
9,886
The pro units do go up to 100kV, but I'm not greedy lol. The only other thing is to make a cascade/ Cockcroft Walton as you are aware. Diode/capacitor circuit. Ideally it needs to be 50kV to be worth doing. Through all the reading I've seen it mentioned (as voltage goes up the current goes down). There would have to be many stages to even reach 50kV ?
I have seen two FB Transformers in parallel.
There are a few diy powder coating systems using FB Transformers but would have to find again.
12lbs is not much if it's in a control box lol.
The FBT and switching isn't the problem it's the negative voltage output.
From 6kV to 60kV would be ten stages, and that would be a bit, BUT if the feed was a transformer then there would not be much else to add to the complexity. So it may be worth thinking about.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Can a hv circuit go through two stages?
I don't know the theory but if stage 1 produced 10kV could that then go into a multiplier because each time it is doubled?
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Sorry I was slow there lol
How do the components handle those high voltages?
I didn't think they existed.
 
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Thread Starter

Roger60

Joined Feb 29, 2020
34
Just found these. The small transformer will produce 20kV and they are fitted in the powder coating cascade (multiplier) last picture Screenshot_20200306-213755.jpgScreenshot_20200306-213829.jpgScreenshot_20200306-214127.jpg
 

MisterBill2

Joined Jan 23, 2018
9,886
Can a hv circuit go through two stages?
I don't know the theory but if stage 1 produced 10kV could that then go into a multiplier because each time it is doubled?
OK, here are quadrupeler circuits, after that it becomes a cascade/ Cockcroft Walton circuit. No, it does not double the output voltage. The multiplier circuits multiply the peak value of the input voltage by the number of stages, which is typically the number of diodes. A doubler only doubles the AC input voltage. And now those small transformers shown in the pictures are another version that I have not worked with. 20 kV fed into a double could indeed give you 40 kV.
One word of caution is that some of those circuits do not deliver a symmetrical waveform, and most multipliers depend on a reasonably symmetrical input waveform. So with some drivers they may not work as hoped.
 
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shortbus

Joined Sep 30, 2009
8,971
I'm going to bow out of this! Mrbill either has me on his ignore list or is just purposely giving different information to you. And I am not going to compete with him any more. That said if you want to use a flyback the circuit I linked to in post #17, or the one you posted in #16 would work for the flyback, as that is what they were designed for.
 

MisterBill2

Joined Jan 23, 2018
9,886
Sorry to have offended you, Shortbus. That circuit in #16 appears to deliver a symmetrical drive, while the one in #52 does not. And I don't recall ignoring you.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Shortbus, please do not bow out. I really value both parties opinion and would like to get this done with all involved.
As the saying goes, two heads are better than one.
In this case it's two and a bit, and I should be the bit that's missing.
 

shortbus

Joined Sep 30, 2009
8,971
Sorry to have offended you, Shortbus. That circuit in #16 appears to deliver a symmetrical drive, while the one in #52 does not. And I don't recall ignoring you.
You seem to disagree with everything I'm saying, things I have actually found by spending time looking to help him.

Do you even have a powder coater? Or even done any? I have.
 

Thread Starter

Roger60

Joined Feb 29, 2020
34
Thank you for coming back here ( I hope )
I have received the FB Transformer and there's a but here.
The circuit is complete however the ic555 is getting hot.
It was followed to the letter and the only load is my mini oscilloscope.
The circuit is post 16 will have to look back.
 

MisterBill2

Joined Jan 23, 2018
9,886
You seem to disagree with everything I'm saying, things I have actually found by spending time looking to help him.

Do you even have a powder coater? Or even done any? I have.
None of my comments were about powder coaters or electrostatic painting systems, they were all about power supply and high voltage circuits. A high voltage circuit for an image tube or a gas laser or a geiger tube is still a high voltage low current supply. And a voltage multiplier is the same circuit regardless of the load, and needs a symmetrical drive wave to work as intended.
 
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