The Remote Control Tester designed here uses the Monostable Mode operation of a 555 Timer. The circuit can be used to check the working of any remote control. If the remote control is working then it produces a beep sound at the buzzer and the LED glows. And if it is not working they are silent. The remote control tester designed here uses the monostable mode of operation of a 555 Timer. The remote tester uses three key components.
The infrared receiver:The infrared receiver used in this project is the TSOP1738. It is an infrared detector at a centre frequency of 38 Khz of the incoming infrared light. The characteristics of this infrared receiver is that when it detects infrared signal at about 38 KHz its output terminal goes LOW (0 V) and when no infrared signal is present it remains high (5V).
Transistor: The same kind of transistor is used as in SHORT CIRCIT DETECTOR and the working is also same.
555 Timer: The 555 Timer is used in the monostable mode of operation as described in SHORT CIRCIT DETECTOR.
1. 555 Timer
2. Resistors (4K7, 100R)
3. Capacitor (47uF, 1nF)
4. Infrared Receiver (TSOP 1738)
5. 5V Buzzer
7. Transistor (2N3906)
The output of the 555 Timer is connected to a 5V Buzzer and a LED. When a remote control is brought near the infrared receiver and a button is pressed in the remote, signals at 38KHz goes out of the remote (if the remote control is in working condition). This signal is received by the infrared receiver and gives out its output terminal LOW (almost 0V which is less than 0.7V). Now the base of the transistor gets less than 0.7V and this activates the transistor. This in turn triggers the 555 Timer as the transistor connects the trigger terminal of the 555 Timer to the Ground by connecting its emitter and collector terminals. Hence the output of the 555 Timer goes high making a sound in the buzzer and glows the LED. So when the Buzzer sounds and the LED glows, it can be understood that the remote control is working.
In contrary, if the remote control is not working, the infrared receiver will not receive any infrared signal and it will give its output terminal HIGH which will not activate the transistor and consequently the 555 Timer will not be triggered and the Buzzer will not sound and LED will not glow. This condition makes us understand that the remote control is not working.
Circuit Diagram :