> resistors they both look very similar
I think you mean capacitors

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I checked one of my suppliers and they dont sell 100 uF Ceramic capacitors.
I also checked my batch (as long as they were out) 104 for 100 nF.
http://www.marvac.com/funpages/ceram...itor_codes.htm
Checks out. The letters are in fact Temperature Coefficient Codes. Never payed any attention to it before

. And i've built a fair amout of circuits.
I'm pretty sure something's mixed up here . An 100 uF capacitor 99% of times are eletrolitic ones (#3). They can also be electrolitic and non polarized, but those are mainly used in audio systems.
Can you post the schematic of the circuit? It might help.