Date: Wed, 16 Dec 2009 20:28:01 -0800
Reply-To: David Marshall <mailinglist@FASTFORWARD.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Marshall <mailinglist@FASTFORWARD.CA>
Subject: Re: Audible Idiot "Light"...EE Inventor Wanted
In-Reply-To: <83404.99839.qm@web83607.mail.sp1.yahoo.com>
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This is quite simple. No need to send me $100
The blue
wire coming form the Alternator makes 12V when it is producing
current. When it is not making current, it goes to ground. The
idiot light in the dash is connected to 12V from the key and to the blue
wire from the alternator. When the key is on and the alternator is
off the light sees a difference of 12V across it and the light goes
on. Once the alternator starts making power both sides see 12V and
the difference across the light is 0V and the light goes out.
So all you need is a relay and a 12V buzzer and a source of 12V that is
on only when the engine is running, which is the fuel pump relay.
With this design, you would hear the buzzer for about 1 second when you
turn the ignition on but it would promptly go off if the engine is
off. Picture it as a pre flight test of your warning system - how
anal is that! ;-p
RELAY 1
30 - output of fuel
pump relay
85 - 12V from ignition key
86
- blue wire from alternator
87 - buzzer
If the engine is running, the fuel pump is running so you have the
source of 12V for the relays input. When the engine is off, the fuel
pump is off, so the 12V source is gone so the buzzer can't sound if the
relay was turned on. As with the idiot light in the dash,, a relay
needs 12V difference across terminals 85 and 86 so the relay will be OFF
when the alternator is making power and the key on with our above circuit
- 85 is 12V from the key and 86 is 12V from the alternator. The
instant the alternator fails (belt snaps or the like) it will stop making
12V and goes to ground, the difference across the 85 and 86 terminals goes
to 12V, the relay will then turn on thus turning the relay on and sounding
the buzzer that is attached to terminal 87.
David Marshall
VW Adventure Driver and BMW Adventure Rider
http://www.hasenwerk.ca
On Wed, December 16, 2009 16:55,
Richard Koerner wrote:
> Volks,
>
> I'm pretty
anal about my cherished Vanagon. Always looking...always
>
listening...follow the recommended maintenance activities by the book
and
> then some. Yet...it happened to me on my recent
half-country trip from
> San Diego to Brownsville, Texas.
The dreaded "red lights" suddenly
> noticed in the
instrument cluster; in my case, broken water
> pump/alternator
belt. I saw the lights and immediately pulled off the
>
highway. Were they on for seconds or minutes?....surely not more
than a
> minute or two. And I may have squeaked by...no
apparent engine or gasket
> damage, but time will tell on that
one.
>
> What we need is a simple fix. A small
"box" of electronics, wired in so
> as to detect any of
the red LED's coming on (oil pressure, alternator,
> coolant
temperature), with a LOUD piezo speaker blasting you to "get OFF
> the road and shut down IMMEDIATELY!!!. Doesn't have to
speak
> words....just be obnoxious.
>
> Sure, the
idiot lights do provide some measure of alert. But the vast
> windows of the Vanagon provide plenty of reasons for not driving
while
> staring down at the instrument cluster, especially on a
bright sunny day.
> We need a backup system...Audible.
Airplanes have these kinds of things,
> even "stick
shakers" to try to convince you to avoid a stall.
>
> So....any Electrical Engineers out there? I'm a Mechanical
Engineer...I
> can't do it, but it's easily within the realm of
some EE. Maybe it's
> already been done. I'd pay
$50-$100 for such a contraption...peace of
> mind...and freedom to
keep looking out the windows. Sound interesting?
>
> Rich
> 85 Vanagon not a Westy but I love it to death
> San Diego
>
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