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From: Kristian Jonsson
To: 'alpines(at)autox.team.net'
Subject: RE: alpines(at)autox.team.net digest #837 Wed Oct 14 04:05:00 MDT 19
98
Date: Wednesday, October 14, 1998 4:35AM
>It is not that easy
>I have no electronic ignition (I wish I had), just the old fashion way.
>But there are no way I can connect the rev. counter in series because no
>voltage is going through the rev. counter. (from the flat connector to the
>round pin connector). The engine donīt start because there are no voltage
>to the coil.
>Some other electrical rev counters have the wire going one turn around (a
>transformer) outside (or inside) on the back of the rev counter. But
looking
>inside this rev counters, there are only tiny wires, clearly only made to
>take very weak current.
>Are we talking about different electrical rev counters??.
>To me it it looks like the rev counter need current to make it work and
>signals from the coil to the rev counter brain so it knows where to point
>the needle.
>If I do like that, it works.
British Leyland and Jaguar used tachs that have connectors that match
your description, and they opperate the same way that the alpine
tachs work. Dont be put off by the size of the wire, its short, and not
that small. The primary circuit only needs about 10 amps peak,
and with a typical 4cyl dwell, you can draw no more than 5amps
average. The wires are small becuase they go straight to the
current transformer. If the whole wire from the ignition to the coil
were that small, then you'd have major voltage losses, but
in fact several inches of #20awg wire would not cause significant
voltage loss for that current level.
The ignition switch wire goes into one connection, and the coil
feed wire connects to the other. The transformer is internal.
Connection polarity is critical, or the tach wont work.
You say you arent using and electronic ignition, perhaps you are
using a "hot" coil, or a coil designed for a ballast restistor, and you
havent one connected?
Sounds like the tach is swamped with too much peak current,
which once again sounds like the reason that the tach works
when you put the tach across the ignition to coil feed wire.
Jarrid
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