time-lapse unit

elektor july/august 1985 1110111B.111 moitigie Which amateur film maker has not wished sometime that he could experiment with time exposures? For- tunately, it is now possible with a simple electronic circuit to see the grass grow without having to sacrifice a night"s sleep. The circuit consists of a clock oscil- lator, N1-N2, a 12-stage binary counter, IC2, and a monostable, N3-N4. Preset P1is adjusted to make the highest oscillator frequency about 16 Hz. When switch S2 connects pin 4 of N2 to pin 8 of N3, the circuit works in "real time". Each successive step of S2 from this position doubles the time between exposures. At the minimum oscillator frequency of 0.5 Hz, and S2 connected to the Q11 output of IC2, intervals of up to two N1 . N4 = IC1 = 4093 16 IC2 4040 CLK hours are possible between exposures. As the signal at the wiper of S2is a square wave, which is — by definition — logic 1 for half the time, it is essen- tial that it is shaped in a monostable. The duration of t...