Thrifty 2Hz Clock


CMOS
circuits are known for their low current consumption. This is
particularly important for battery-powered circuits. Unfortunately,
oscillators often require quite a bit of current. We therefore propose
this oscillator circuit that has a very low current consumption (about 3
µA). The circuit is powered from a type LM334Z current source. The
current has been set with R4 to about 3 µA. This is sufficient to power
IC1 and the oscillator circuit around X1. The oscillator generates, with
the aid of a cheap watch crystal and a few surrounding parts, a signal
that is subsequently applied to the divider in the 4060 and results in a
frequency of 2 Hz at pin 3 (output Q13). The level of the output pulses
is a lot lower than the nominal 5-V power supply voltage (IC1 is after
all powered from a current source with very low current). That is why
the signal on pin 3 of IC1 is amplified and inverted by T1. IC3a finally
turns it into a proper square wave with acceptably steep edges.

Circuit diagram:

Thrifty 2 Hz Clock Circuit

Thrifty 2-Hz Clock Circuit Diagram


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