At 11:41 AM 1/30/2009, Mike S wrote:
>TCA700Y, they are hard to find at a reasonable price these days. If you
>need one, the best bet is to try and get one off a junk instrument
>cluster. They were used on many/most VW/Audis from the mid '70's
>through the '80's.

Sounds like a candidate for a +12v regulator and a few diode drops,
or a +5 and a five-volt zener on the ground lead.  It's not like it's
a precision application...

Newark Electronics, an outfit not known for low prices, sells
LM340T5s for $1.34 in onesies.
<http://www.newark.com/jsp/displayProduct.jsp?sku=37C1790&CMP=KNC-G10000683&HBX_OU=50&HBX_PK=LM340T5>

And I think this 5.1v zener would probably do, $0.34 in onesies.
<http://www.newark.com/fairchild-semiconductor/bzx55c5v1/zener-diode/dp/58K8776>

If you do either of these tricks, make sure the voltage doesn't end
up low, or your coolant light will never stop blinking...spec is 10v
+/- 0.5 but I'd recommend
10v +0.5 -0

Remember that zener diodes go in the circuit with the band (or arrow)
pointing toward the plus side, in this case the ground lead of the regulator.

--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage," '85 GL "Poor Relation"