PWM injector driver

[Greg Hermann]

At 1:45 PM 4/8/01, Carter Shore wrote:
>Hello listers,
>A while back I worked on some swedish (SAAB-Scania)
>printers that used a capacitor voltage doubler circuit
>to do peak/hold for the print solenoid driver.
>The capacitor was switched in series with the supply
>voltage to supply 2X voltage when the solenoid fired,
>then it decayed to 1X voltage for the remainder of the
>firing event.
>These drivers were remarkably reliable, the circuit
>was dead simple, and used good quality film capacitors
>of a few microfarads, along with a couple of diodes to
>implement the doubler.
>
>I bet I could dig up the schematics and scan them if
>anyone is interested.
>
I think this observation is right in line with what Bob Hale said about the
last generation of high speed, electro mechanical teletype print hammer
throw circuits being something that might adapt very well to driving
injectors.

---But I think the teletype stuff Bob mentioned was a _LOT_ more hot-rodded
than what you are talking about. I think he said they were up to something
in the neighborhood o 230 vdc for the "peak" driver voltage on the last
generation of teletypes!

Greg


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