Fred,
Sounds like you're talking about the capacitor that was fitted to earlier
pumps (prior to the use of a diode). It's probably a 47 uF (microfarad)
capacitor rated at 400 volts. Later pumps have an unusual looking diode
that is shaped like a small cylinder with black and red leads.
In the transistorized setup, the points switch the current to the transistor
(the resistor limits the switching current), the transistor switches the
current
to the coil, and the diode allows the "backflow" of current--induced when the
transistor is switched off by the points and the field in the coil collapses--to
bypass the points and limit arcing (which is what erodes the points in the
first place). This is called a "flywheel diode" and is often placed across
inductive loads to prevent arcing (some relays have them internally).
Anyway, you can dispense with the capacitor.
bs
***************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
***************************************************************
Subject: Re: Transistor Fuel Pump
> Fred Wescoe wrote:
>
>>A quick question before I seal the pump up and return it to place. I removed
>>the black plastic cap. I placed the transistor, new diode and resitor as
>>indicated in the drawings. I have what I assume is an original diode
>>connected in the original circuit. It has these markings; 400V- and then what
>>appears to be 47 ohms and then 10% plus or minus. Is this the diode and do I
>>just throw it away, I assume it is being replaced by the transistor?
>>
>>
> What color is it? Does it have any white, black or colored bands on
> it? Could it be 47 uf or ufd instead of ohms?
> --
> John Miller
|