Leakage current. Using an electrolytic as a timing capacitor is seldom a wise thing to do. You can end up with such severe leakage (and it doesn't take much) that the circuit actually stalls and sits there looking stupid (sorta like my dog).I noticed there's a huge difference between electrolytic and non-electrolytic capacitors; I used a 47μF 100V non-electrolytic capacitor instead of the 10μF 63V electrolytic and the frequency went up instead of going down. How can that be?