circuit diagram of Remote controlled switch project

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• This is a schematic circuit diagram of a remote-controlled switch for home appliances.

• TSOP1738 used in the circuit for detecting IR signals from the remote.
• This circuit works with any infrared remote used for TV, DVD, USB player, etc. In this circuit there are two relays are used, the first relay is used for giving input signal to ic according to changing pulse from the sensor, the second relay is used for connecting load ie- Fan, light, etc.
• you can on or off any appliance by this circuit. This is worked up to 5-10 m distance from remote.

• This remote-operated/controlled circuit is designed to switch on or off any home or industrial appliance by using the TV/DVD remote. The circuit can be operated up to a distance of 5-10 meters depending on the remote user.

The circuit consists of a step-down transformer X1 (6V-0-6V, 250mA secondary), 5V regulator 7805 (IC1), to 5V regulated output, 1 change-over (C/O) relay, a timer ic NE555 (IC2), an IR receiver module (IRX1 TSOP1738) and some other discrete components.

The circuit works on 5V DC, which gets input voltage from transformer X1 and regulated by IC1. The circuit works by pressing any key on the remote. It also operated manually by pressing switch S1 to ‘on’ state. After on the switch, s1 remote-controlled disabled and then the only manual operation can work. The TV/DVD remote produces a 38kHz frequency. The IR receiver module operates at this frequency. It is used to control relay RL2.

Construction of Remote controlled switch circuit

The relay (RL2) triggers IC2 which is connected in bistable mode to control the relay 1(RL1) which is connected with the appliance(Fan, Light, etc). Timer IC2 toggles relay RL1 when switch S1 is pressed momentarily. Threshold and trigger input pins 6 and 2 of IC2 are held at one-half of the power supply voltage (5V) by resistors R2 and R3.

When pin 3 of IC2 is high, capacitor C4 charges through resistor R4, and discharges when the output pin 3 is low. When switch S1 is pressed, the capacitor C4 voltage is applied to pins 2 and 6 of IC2, which causes the output of IC2 to change from low to high, or high to low. When switch S1 is released capacitor C4 charges or discharges to the original level at the output pin 3 of IC2.

This operation can be operated by relay1(RL1) when IR signal(ray) are not incident on the TSOP1738 sensor, its output at pin 3 remains high. When any TV remote key is pressed, IR rays fall on the TSOP1738 and its output goes low. At the same time relay RL2 energizes for a few seconds through PNP transistor T2 (BC558).

Working of Remote controlled switch circuit

Initially, when there are no IR rays falling on the IR receiver module, its output remains high. Transistor T2 is in cut-off condition. Relay RL2 does not energies and hence IC2 does not toggle. As a result, home appliance connected at the contacts of relay RL1 remains switched off. When you press any remote key for the first time, the IR receiver module’s output goes low and the collector of the transistor T2 goes high. Relay RL2 energizes and triggers IC2. The output of IC2 goes high and relay RL1 energizes to switch on the appliance. Once relay RL1 is energized it remains in that state. So the appliance which is connected at the contacts of relay RL1 remains switched on. Now when you press any remote key again, relay RL2 energizes and re-triggers IC2. Then the state of ic2 changes. The output of IC2 goes low and relay RL1 de-energizes to switch off the appliance. Once relay RL1 de-energizes it remains in that state. So the home appliance remains off. This cycle repeats when any key of the TV remote is pressed to switch on/ off the home appliance. Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. TSOP1738 must outside of the cabinet to get a signal from the remote.

Components list-

Sensor

TSOP 1738-1

Capacitor

10uf 16v-1

1uf 16v-1

100uf 25v-1

0.01uf(103)-1

0.1uf(101)-1

Resistance

100-1

470-1