DIY injector cleaning

[Bruce Bowling]

> 
>  Andris,
> i guess the answer was NO there isnt a GOOD way for the DIY to clean injectors other than a additive in
> the tank.
> 
> Jimm L.
> the injector " guru"
> 
> 

A question:

Could one accomplish a sort of ultrasonic cleaning by simply driving the
injector coil at a high frequency, like 10 - 30 Khz, while backflushing?
Seems to me if one got the duty cycle right one could get the pintle to
just open and close slightly, producing an active high-frequency "hammering"
on the pintle. This, with the backflushed cleaning liquid under pressure,
should help clean the unit.

So drive the injector with a 555 timer coupled to a driver transistor. The
following circuit comes to mind:



  +12       +12                   +12
   |         |                     |
   |         |                     |
   |     ----------             Injector
  30K    |  4,8   |                |
   |     |        |            b   |c
   |-----|7 555  3|----330ohm--- TIP120
 130K    |        |               NPN
   |     |6,2 1  5|                |e
   |     ----------                |
   |      |   |  |                gnd
   --------   |  |
   |          | 0.01uf
 470pf        |  |
   |         gnd gnd
  gnd


The 555 timer is running at 10 Khz, at about 55% duty cycle. The drive transistor
is a TIP120 Darlington (NPN). Due to the duty cycle, the drive current should
be fine for any injector 2 ohms and up.

All parts are stocked at Radio Shack, and the whole circuit will cost under $10.00, 
including perf board. This is as DIY as it gets.

- Bruce

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                 Bruce A. Bowling
                 Staff Scientist
   Thomas Jefferson National Accelerator Facility
    12000 Jefferson Ave - Newport News, VA 23606
                 (804) 249-7240
bowling at cebaf.gov  http://devserve.cebaf.gov/~bowling
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