Voltage Regulator – Ron’s 70 S2 Crossflow
The original 10V regulator is a fairly crude mechanical unit that makes a fair amount of electrical noise and has very loose tolerances regarding 10V. Check out:
http://www.lotus-europa.com/manuals/misc/electrical/gauges.html I replaced it with an LM2940T-10 voltage regulator (Digikey). All the info you need to duplicate my circuit is in the data sheet for the part. It is small enough to locate between the Temp and Fuel gauges secured with a couple of short screws. You should use a small heatsink on the regulator as shown in the picture (also available from Digikey) I used it to power all the gauges (I added the oil pressure gauge. It will now be consistent / not change with engine speed / battery voltage although it may read slightly low all the time.)
The circuit diagrams below.
If you want to retain the original regulator adding .01 and 1 µF capacitors, in parallel to ground at the case, to the input and output will dramatically reduce electrical noise. It will still have poor stability and loose voltage accuracy.
