The circuit uses a CA3060 triple OTA (two units serve as switched current generators controlled by a third amplifier). A CA3160 BiMOS op amp serves as a voltage follower to buffer the 0.0022 ÂµÂ¥ integrating capacitor. The circuit has an adjustment range of 1,000,000:1 and a timing range of 20 Âµ& to 20 sec. The `ON-OFF` switch actuates an LED that serves as both a pilot light and a low-battery indicator.
The LED extends battery life, since it drops battery voltage to the circuit by approximately 1.2 volts, thus reducing supply current.