Remote control tester Circuit
This is a simple remote controller tester circuit based on infrared sensor IC TSOP 1738. When the IR waves fall on the sensor it output changes to low state. This makes the transistor Q1 (BC558) ON and LED will blink according to the code contained in the signal. So for the press of each button the LED blinks in different ways. This is a good indication of the working of remote. The diode D1 drops 0.7 V to give the IC ~ 5V supply from the available 6V. R2 is a current limiting resistance.
The transistor BC558 can also be replaced with others like BC158, BC177, S8550, 2N2905. If you find the LED glowing all the time even if you cover the IR sensor it may be a problem with the IC. This ICs output with no signal will be high and with signal it will become low. May be the quiescent current through IC1 itself is biasing Q1 may be your specimen if of quite high gain. You can try by shifting the emitter of Q1 to R2 IC1 junction, which may solve your problem.
You can modify the remote control tester circuit to connect a piezo speaker between the transistor collector and the negative terminal for sound indication.
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Remote Control Tester Circuit Diagram with Parts List
|Infrared Sensor||IC TSOP1738|
|PNP Transistor , Q1||BC558|
- Use a 6V battery to power up the circuit.
- This circuit can be used to test remotes operating in the 38Khz carrier frequency.Almost all remotes fall into this category so no problem.
The Remote control tester circuit uses the IC TSOP1738 for its working. This is an IR remote control receiver module which is embedded with a PN diode and a pre-amplifier to form one pack. This IC produces an active LOW state output and provides a HIGH +5 Volt at OFF state. That is, when IR radiations with a frequency of 38KHz (sensitive frequency of TSOP1738) are received by the IC, its output will be LOW. All the unwanted rays coming from sunlight, high wattage bulbs and so on could produce an undesired output for the sensor. This can be avoided by using a Band Pass Filter (BPF), an integrator circuit and an automatic gain control.
The pulses that are received from the IR Transmitter are amplified using a control module inside the IC. The PIN diode produces a signal corresponding to the signal it receives. The AGC adjusts the gain to a certain level according to the signal it receives from the PIN diode. The AGC sends its output to a BPF and filters unwanted frequency. These frequencies are then passed on to a demodulator and then to a transistor. The collector output of the transistor is obtained at Pin 3 of the IC.
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