"ian field" wrote in message
...
Some glass encapsulated thermistors I salvaged from some scrap telephone
equipment - I was hoping were RA53 as sometimes used to stabilise the
amplitude of simple AG signal generators.

Having found the data sheet online, I find that the RA53 has a room temp
res' of 5k - the one's I have are nearer 200k, so they might be RA25.

Anyone know where to look for info that might help in re designing such
circuits to accommodate the higher resistance thermistor?

TIA.



I've been down the same path with those nice telecomms thermistors but they
only start usefully dropping their resistance in oscillators running maybe
50Vrms. (They've got to see the high voltage just to dissipate a little
power in the high resistance bead, hence giving some useable resistance
change).

The 5kohm RA53 was perfect for the job but haven't seen 'em for the past 10
years. I now use 'DF08', DIL package, 1Amp bridge rectifiers. The diodes are
very well balanced, allowing clean sine generation.