RV Start/Stop (glow plugs) Relay Help

[notme]

Hello,

I need a simple but reliable way to hold a small automotive 14vdc relay on
for a few seconds after it has lost power. Basically, I'm thinking a
capacitor accross the +/- leads of the relay coil fed in series with a diode
to allow a fast charge (and parrallel to that diode) a resistor to allow a
more paced discharge.

This is for the stop portion of the relay and I'm thinking that just as the
engine is about to die (dc to power the relay will cease, and the relay will
now flip positions and supply a glow plug siganal), and the engine may
recover and re-start.

Any thoughts on if this approach will work with the relay.

Thanks for the help.

Tom

 

[John Miller]

notme wrote:

I need a simple but reliable way to hold a small automotive 14vdc relay on

<snip>

Tom, I tried to email you, but you didn't leave a clue in your message.
Please email me at the address in my sig.

--
John Miller
Email address: domain, n4vu.com; username, jsm

This will be a memorable month -- no matter how hard you try to forget it.

 

[JeffM]

hold a small automotive 14vdc relay on
for a few seconds after it has lost power.
I'm thinking a capacitor accross...the relay coil
Tom (notme)

You're on the right track.
http://groups.google.com/groups?&q=darlington+capacitance-multiplier+OR+capacitor-multiplier

 

[Peter Bennett]

On Thu, 03 Jun 2004 05:55:37 GMT, "notme" <notme@worldnet.att.net>
wrote:

Hello,

I need a simple but reliable way to hold a small automotive 14vdc relay on
for a few seconds after it has lost power. Basically, I'm thinking a
capacitor accross the +/- leads of the relay coil fed in series with a diode
to allow a fast charge (and parrallel to that diode) a resistor to allow a
more paced discharge.

This is for the stop portion of the relay and I'm thinking that just as the
engine is about to die (dc to power the relay will cease, and the relay will
now flip positions and supply a glow plug siganal), and the engine may
recover and re-start.

I assume this is for a diesel engine - if so, powering the glow plugs
as the engine is stopping should not encourage the engine to restart.
The glow plugs are used before starting to pre-heat the cylinders, to
make the engine start more easily. If the engine has been running,
the cylinders are already hot enough to allow the fuel to ignite
easily, without help from the glow plugs.

To stop a diesel engine, you simply stop delivering fuel to the
injectors - without fuel, the engine can't continue to run.

On my boat, the engine has a solenoid to pull the fuel shut-off lever
on the injection pump. To stop the engine, I press the button that
powers the solenoid, and must _hold_ the button pressed until the
engine has stopped turning.



--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
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