Suitable design for a home made Flocking Applicator ...

Discussion in 'The Projects Forum' started by odintheterrible, Jun 16, 2010.

  1. odintheterrible

    Thread Starter New Member

    Jun 16, 2010
    Greetings one and all ...

    I recently decided to refurbish the interior of my '91 Toyota MR2 and decided that I would like to 'flock' the dash, centre console and other bits etc to inprove things. As this is all I have in mind, buying a professional flocking applicator seems a little extreme at around £700 a pop !! So, I started looking round to evaluate the possibility of building a unit myself ... give the limited use it will get.

    The problem I've encountered is that most of the stuff out there on the 'Net seems to be quite old and much of the schematics and component used appear to be based upon older, and now unavailable items or steam driven technology. I have tried looking at buying a 'kit' (based upon the Cockroft-Walton Multiplier pricipal) but the supplier can't/won't quote a figure for the output (needs to be in the range of about 35KV + pullin' about 40 micro amps if I use battery power (6 or 9VDC) although mains power (230VAC) would be preferable) and it seems like a bit of a waste of money to have to buy the kit in order to establish the output !?!

    Now I must add at this point that my experience of High Voltage applications is ZERO !!!! ... so I'd be most grateful for assistance with the following ....

    ... I came across an article which appears to describe a circuit which meets my needs almost exactly, trouble is that some of the components appear to be unavailable (due to age of article) and a bit of the circuitry leaves me mystified; so ... and here's the big ask ... would one or other of you kind souls care to step up to the plate and update what I've found so that I can have a fighting chance of building it ??? ... PLEASE :rolleyes:

    My main sourcing issues seem to be mainly associated with; C2, L2, T2 and Thy1 (have the pdf spec sheet if required)
    Thy1 Thyristor S0802MH by Tag Semiconductors Ltd (pdf spec sheet available)
    T2 Transformer 240v : 240v 12vA type DB247
    T1 Motorbike ignition coil from any bike repair shop or scrap yard
    Here's the circuit diagram I found ...


    ... and here's the info that went with it ...

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    If you only need 30 KV or so to attract the flocking, then that circuit is really crazy. Auto ignition coils produce 30 - 40 KV from a 12 volt input. I would think that driving the primary with 20 times the usual voltage might simply fry the coil.

    The circuit at the link should do for the high voltage - . You will need to run down some 1N4007's to rectify the output so you place DC on the parts.
    Last edited: Jun 16, 2010
    odintheterrible likes this.
  3. Darren Holdstock

    Active Member

    Feb 10, 2009
    That's a capacitive discharge ignition circuit, the output of which can be lethal. Mind how you go, to say the least.

    In its proper state with the secondary terminated by a spark gap, the peak voltage at the secondary will be limited by the width of the spark gap. With no gap to flash over, the secondary voltage can be huge, and all that energy has to go somewhere. Usually it flashes over the insulating resin in the transformer and blows up the primary drive circuit. Indeed, this is what happens to many modern ignition systems if the spark plug is absent - they self destruct.

    If you're not familiar with HT circuits, this isn't the one to start with. If the Cockcroft-Walton kit mentioned is sold for flocking application purposes then I'd go with that one, it would be much less likely to kill you. It would still be tricky - all the circuitry at the HT end would require special construction techniques to prevent flashovers, and I couldn't vouch for the effectiveness of the inherent current limiting, but you'd live to have another go if it doesn't quite go right first time.

    If you must use the OP circuit, then replace the vehicle ignition coil with the transformer from a gas cooker ignitor. It's the same circuit, except that the output energy is limited by design, and by legal safety standards. Work out how much energy is discharged by the cooker ignitor primary capacitor (0.5XCXV^2), and don't exceed this figure.
  4. odintheterrible

    Thread Starter New Member

    Jun 16, 2010
    Thanks for the valuable input/info ... the Cockcroft-Walton kit isn't sold specifically for flocking ... I believe it is offered as a negative ion generator ... the suitability for the flocking application was a suggestion from another source ... but it's difficult to judge the fitness for purpose without the output figure which the supplier won't quote.

    I was wondering, since posting, if this kit might be more suitable ...

    Code ( (Unknown Language)):

    Negative Ion Generator Kit

    Input: 9...12VDC, output: 3...7kVs. This ion-generator regenerates negatively loaded air particles (air-ions).

    Technical data:

    • Operating voltage: 9...12VDC
    • Current consumption: approx. 80...150mA
    • Output voltage: static, approx. 3.000...7.000V peak value
    • Board dimensions: approx. 54 x 44 mm
    Again, thanks for the info and guidance.
  5. Darren Holdstock

    Active Member

    Feb 10, 2009
    I'm afraid I don't know the requirements of the flocking process, so I couldn't say. I can tell you that this kit will give a very spiky output, if that's OK, and the voltage won't be very well regulated.

    Bear in mind ionisers usually have current limiting on the outputs in the form of a long chain of 10 Mohm resistors (or thereabouts), otherwise they tend to give off painful little lightning bolts when touched. Safe, but painful. Be wary of smoothing the output with a high-voltage capacitor though, as this will increase the amount of energy delivered per shock. Even if the HT PSU circuit is current limited to a safe level, the addition of a large enough output cap can make it dangerous again.
  6. John P

    AAC Fanatic!

    Oct 14, 2008
    People building model railroads sometimes use these devices to make grass stand up on the scenery (the scenery base is previously coated with glue). Here's a thread about it:

    The high-voltage components are taken from electric fly swatters or negative ion generators. They say it's safe, as there's very little current available from the high voltage source. I hope that's true.
  7. someonesdad

    Senior Member

    Jul 7, 2009
    There are also methods of spraying chopped fibers onto adhesive surfaces to provide a decorative surface. I don't know if that's what you're after, but you can buy the kits pretty cheaply in woodworking supply places.