AoE Figure 2.11. Pulse generator

Push the switch for switching on the lamp for 80ms. This circuit is a variation from AoE "Pulse shaper" (page 78). It is not possible to change the pulse duration arbitrarily by changing the time constant e.g. for a minute, because if the capacitor's value is increased, the charging time is also increased (more time needed to fire again). If the 10KOhm resistor is increased to e.g. 1MOhm, the third transistor will not conduct, and the lamp will constantly on (increasing the 10KOhm resistor to about 100KOhm will cause oscillations, but this can be fixed by placing a parallel resistor to the capacitor). But this circuit can be used for switch debouncing.

published 9 years ago