The step from an electro to high quality high stability is a big one.
If the OP wants reasonable advice, describing the application a bit is
probabably a good idea.
Whats important to you:
voltage? frequency range? temp range? current in the capacitor,
space available, capacitance linearity with applied voltage,
leakage, stability over time, cost, microphonics.... its a long list.
Probably only one or two really matter in any specific app.
The only case where a non-polarized capacitor is not a better
replacement for a polarized one (ie an electro) is if size or cost is
significant. Electros are high-capacitance-density, cheap and
cruddy compared to most anything else.
Bill Sloman wrote:
At 02:58 15-2-2006, you wrote:
Im wondering what i can use instead of Electrolytic capacitors, what
is high quality high stability polarised capacitor at value of 0.01uf
any ideas pls
Hi Marc - the right user-group for this sort of question is
sci.electronics.basics. The answer is, that for a capacitance as low as
0.01uF you don't need to bother using a polarised electrolytic capacitor
at all - metallised film capacitors are much better capacitors. If you
want particularly high quality, go for polypropylene film - Farnell list
a 0.01uF (10nF) +/-1% part with 160V DC (100V AC) maximum working
voltage under order code 303-8543 for 1.3 euro each.
If you were prepared to use an electrolytic for the job, a much cheaper
ceramic disk or chip part would presumably be perfectly adequate (and
better at very high frequencies). Polyester metalised film capacitors
can also be pretty cheap.
If you are primarily interested in temperature stability, polystyrene at
110ppm/C is better than polypropylene at -200ppm/C, and polyphenylene
sulphide is better still
"from -55°C to +85°C, PPS is virtually flat at 7 ppm/°C" but I've only
used it in surface mount capacitors. RS Components stock PPS parts.
Bill Sloman
