Circuit Project Electronic

These circuits show methods of changing the operating frequency of astable LM555 timers electronically. Any source that can drive the base of transistor Q1 can control these circuits.
The advantage of using this type of frequency control is that the duty cycle of the timer is not affected when the frequency is changed. [...]

It is the circuit delays like model easy onely. It use control 3Volt electric small-sized fans because of apply to battery 3V or AA CELL 1.5V x 2. When press SW1 the system delays to begin the work. It make the electric fan turns the one period of time. The circuit [...]

This is OFF After Delay Switch Circuit. It is use Mosfet control the work of LOAD get. By have the work is simple be press Switch (Close) and liberate (Open) S1 an electric bell will loud. After C1 is charger within or change R1 [...]