Peter, David, Brian et al, et al. Peter, you wrote: <Could anyone provide a description to the list of what the voltage stabilizer is supposed to do and how it is accomplished? Possibly a contraption can be made from electronic components.>
The 'Voltage stabiliser', as it is known , is a very simple, but remarkable ingenious device. It is simply a bimetalic self heating device which has a switch contact operated by the bimetalic element. The contacts are normally closed, and the current flowing to the instruments causes it to heat up and it eventually opens. If the volts are low, the current is lower (Ohms Law - remember?) and the contacts remain closed for longer. Conversely if the volts are high the current will be higher (still Ohms Law) and the contacts will be open for shorter times. Thus the power/voltage applied to the instruments is kept fairly constant. The effect of the slow switching (about every 10 secs or so) doesn't have any effect on the instruments as they are bimetalic too, and have very long thermal time constants. That bit was the simple bit. BUT, because the instruments are indeed bimetalic, they are also affected by ambient temperatures, I mean a half full tank is a half full tank whether in 140 degrees F or in minus 40 (F or C). So the bimetalic regulator automatically allows for the ambient temperature, i.e. takes longer to heat up if it's cold, therby exactly allowing for the bimetalic instrument to also receive the extra bit of voost to keep the reading accurate in cold weather. The converse is, of course, true for hot weather. This works because the bimetalic elements in the instrument and the regulator are virtually identical. Making an electronic version is not trivial, the voltage stability is easy-peasy, but the temperature correction requires look-up-tables, design data, temperature measurement etc. etc. etc. I do electronic stuff for a living and I wouldn't even start. :-) Just a twopence worth of not-so-humble-opinion. Chris Dupres Surrey, UK. 74 JH
