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HV Electrostatic sticky device increase the force

smilem

Member
Hello, I have this table with electrostatic sticky surface that made by a snake design of tracks and 3000V DC power supply for HV.

My problem is that the table was redesigned from zero, and now the electrostatic sticky force is very low. The tracks were copied exactly.
The tracks are made from copper foil, the 0.2mm double sided tape used to glue a 0.6mm PVC or PP plastic sheet not sure.

Track gap is 3.5mm exacly for 3000V not to arc right.

Any ideas how to make this work?
The PSU PCB are attached.
 

Attachments

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
From my days of maintaining HP Pen plotters, humidity kills the hold-down ability.

From what I can remember from 50 years ago, The plate was made out of about 1/4" Aluminum with a hole in the rear with pins for the 2 wires. Through wear, the pattern under the outer layer became visible.

I maintained about 6 of them, mostly the 7044 and 7047's.

I "think" the material might be vinyl on the outermost surface. Cleaning that surface with methanol almost always helped. Methanol will displace water.

I do remember replacing one hold down surface, but I forget the reason,

I found this: http://www.kerrywong.com/2017/04/30/hp-7044a-x-y-recorder-teardown-lorenz-attractor/ which has a post by one of the creators of the autogrip electrostatic hold-down Platten

Here is a patent: https://patents.google.com/patent/US3916270A/en

It looks like better performance is had by applying the pattern to the back of the top vinyl film film. Possibly screen printing?

The platten was attached with 4 screws. Counterbored, recessed and was surrounded by an insulating material.
 
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smilem

Member
I tried to apply tracks on the top surface with graphite spray, turned to be unreliable and high resistance.
The tracks are now copper foil then 0.2mm double sided 3M 9088 Polyester tape that gles backin of 0.6mm PVC or PP.

How can I increase voltage to 5000V? I attached my schematic.
I looked on ebay for cheap DC to HV power supplies and can't find anything in 5000V range?

Perhaps I can add few caps and diodes to increase the voltage further to 5000V?
 
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unclejed613

Well-Known Member
Most Helpful Member
I tried to apply tracks on the top surface with graphite spray, turned to be unreliable and high resistance.
graphite is conductive, and could cause arcing... i've seen fiberglass PCBs with carbon tracks between traces burned into the surface. easiest way to detect them is running the unit in a dark room and look for any sources of orange or yellow light on or within the board. blue light will be caused by corona discharge.
 

smilem

Member
Found this project https://github.com/Jan--Henrik/electrostatic-adhesion-plate/tree/master/DINA5

What capacitors and diodes do I need? SMD? The project does not mention any specifcations for parts. Now how stupid is that?
The caps seems like polarized ones either.

I also found that "Sparks occur in air when the voltage per mm exceeds 3000V/mm. "
So that makes it safe to use 7000V as my gap is 3/3.5mm and it's benn insulated with tape.

What smallest parts I can get? my space is limited.
 

JimB

Super Moderator
Most Helpful Member
I also found that "Sparks occur in air when the voltage per mm exceeds 3000V/mm. "
Maybe under perfect conditions in a laboratory, but for many year I have used 1000v/mm as the typical dielectric strength of air.
Many factors affect the breakdown voltage, humidity, the shape of the electrodes (sharp electrodes break down the air at lower voltage).

Where you have strips of metal stuck to a surface, it would be wise to use a lower voltage rather than a higher one.

JimB
 

smilem

Member
"Where you have strips of metal stuck to a surface, it would be wise to use a lower voltage rather than a higher one. "

I agree, but the electrosttic force is too low to be usable. Perhaps the 33M safety resistor should be lowered the current perhaps too has an impact of how strong the electrostatic force will be?
 

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