This circuit uses several transistors and relays in addition to active components in addition to IC555. The circuit works automatically opening and closing a pair of curtains.
The S3 switch functions to control it manually and allows the curtain to open or close in part. The output of this circuit will control a DC motor mounted on the curtain pulley mechanism simply to shift the curtain.
How automatic operation works
The circuit is divided into three main parts, namely two-way hooks, inverting circuit and timer circuit. The function of the S3 switch will determine the series to work automatically or manually.
The default circuit in the picture is the position of the S3 switch in an automatic state. Transistors Q1 and Q2 are designed to form a bistable circuit that will determine the A / 2 relay control. Switch S1 functions to open the curtains, while S2 to close the curtains.
When the circuit is turned on, a brief positive pulse is applied to the base of Q2 through capacitor C2. When transistor Q2 is active, A / 2 will automatically activate too. Network capacitor C3 and resistor R4 will form a low current buffer circuit against the relay. Relay A / 2 is a 12V voltage relay that has a coil impedance of no more than 500 ohms.
When the relay is active, the current through the relay coil will be reduced by resistor R4 to save power consumption. When the transistor Q2 turns off, the charge on capacitor C3 will run out, but when Q2 becomes active (either when pressing the switch S1 or when the circuit is turned on), the capacitor C3 will be charged very quickly through the coil relay.
This circuit does not require complex power supply circuits, enough with a 500 mA transformer with rectifier diodes, capacitors and an IC78xx regulator.