This is an IR receiver module tester, which can be used to do on-board testing of IR modules used for remote control of electronic devices such as televisions and video disc players. The circuit is quite straightforward, and it also has the capability of acting as a remote tester. Miniature IR receivers that are sensitive to pulsed infrared radiation are what make up IR receiver modules. These have a pin photo-diode and a preamplifier stage that are both contained in an epoxy casing that also functions as an IR filter. The module is equipped on the inside with an automatic gain controller (AGC), band-pass filter, demodulator, and control circuit. Its output consists of a bipolar transistor with a

resistor ranging from 80 to 100 kilobohm in the collector of the transistor. The collector output of the transistor is high and produces 5V at 5 mA when it is functioning normally. When the pin photo-diode detects the existence of pulsed IR photons, the output of the module is active-low; as a result, it causes a sinking current to occur. The IR receiver module is capable of continuous data transfer at up to 2400 bps or higher, and it is designed with a high level of immunity to light from the surrounding environment. Band-pass filtering and automatic gain control (AGC) work together to eliminate unwanted noise and prevent false triggers. The module will only react to the IR beam if the carrier frequency of the beam is somewhat near to the frequency that is in the center of the band pass. Functioning of the circuit In order to connect the circuit to the positive, the negative, and the output of the module, three miniature crocodile clips are utilized. If the module is operating as it should, the voltage at its output will not change. Because of this, the cathode of LED1 becomes high. Because of this, LED1 will not glow, and the buzzer will not make any noise. When you direct the remote handset's infrared light beam onto the IR receiver and then press any switch, current flows into the output of the IR receiver. In response to this, LED1 begins to flash, and the buzzer begins to beep in time with the pulsations of the IR beam. If, on the other hand, your IR receiver module is broken, the output of the module will not sink current when you direct the remote handset towards the module and press any switch. This is because the module will not send a signal to the remote handset to sink current. Therefore, the LED1 does not flash and the buzzer does not sound in time with the pulsations of the IR beam. The circuit is supplied with power by a 9V PP3 battery, and that voltage is reduced to 5 volts by a zener diode designated ZD1. The vast majority of IR receiver modules can only operate at voltages between 3 and 6 volts. The discharge of the storage capacitor C1 causes the LED1 to rapidly brighten and dim. (EFY In the course of our testing, we had made use of a TSOP1738 IR receiver module.

Construction and quality assurance Construct the circuit on a modest-sized piece of matrix board, then enclose it in a modest-sized cabinet after you've done so. For an audio-visual indication, you should use a red LED with a high brightness and a little buzzer. It will be much simpler to connect to the pins of the module if you first link points A, B, and C to the crocodile clips using red, black, and blue wires. The pin assignment (front view) of several common IR receiver modules is presented in the table below for the purpose of making it easier to identify the pins.