[time-nuts] capacitors for oven controller

[Charles Steinmetz]

Corby wrote:

>I'm working to replicate an oven controller and the schematic I have
>states to check the leakage resistance of the .01uf integration capacitor
>at 50 degrees C.
>    *   *   *
>What would be considered good at that temperature and how would I measure
>it?

If you CAN measure it, without extraordinary measures, it is probably 
not suitable.  Some bench DVMs (e.g., Fluke 8050A) have conductance 
ranges that measure very low conductances (high resistances).

>Also what type capacitor to use? Polycarbonate???

Polycarbonate is very difficult to find these days.  Of today's 
common dielectrics, it's a split decision between PP (polypropylene) 
and PPS (polyphenylene sulfide).  PPS handles higher temperatures, 
but PP has better insulation resistance at elevated 
temperatures.  Another possibility would be PTFE, if one will 
physically fit.  Finally, a C0G (NP0) ceramic could be a good choice.

Best regards,

Charles