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| ICM7555xP | CMOS General Purpose Timer, 555 compatible, PDIP-8 | | | | S3 | 1 | TL074 | Quad Low-Noise JFET-Input Operational Amplifiers, DIP-8/SOIC-8/TO-99-8 | | R15, R20, R22 | 2 Smaller cap (476nF?) for C1 - Ceramic 104s for C10, C14, might be fine, might introduce intermittents - Don't put R8 so close to R26 -- D36/R47 too close Testing before powering up: Clock In - U1-13 (can get at from top when assembled - Stop Switch - 10 ohms between U1-14 and U2-1 when off, more like 1M ohms when off Single Step - 12V through 10k Ohms to U-1-14, more like 1M when off Single Step.

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