This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
We found this simple circuit with headphones listening in Radio Electronics magazine from March...
This circuit was obtained from Maxim documentation. The circuit has 4.5 and 5.5V thresholds for...
This complementary-output amplifier can be used to source a good qualuty signal to high impedance...