This Circuit diagram presented in this schematic is an simple, low-cost, and easy to construct infrared remote control tester. The remote control tester circuit is built around an easily available infrared receiver module (TSOP 1238).
Normally, data output pin 3 of the IR receiver module is at a high level (5 volts) and as such driver transistor T1 is in cut-off state. If the IR receiver module receives a valid (modulated) infrared signal, its data output pin goes low in synchronism with the received infrared bursts. As a result, transistor T1 conducts during negative pulse period and the LED blinks to indicate reception of signals from the remote such as TV remote control.
Also when the TRANSISTOR T1 conducts and the LED blinks , the buzzer connected at the collector of transistor T1 will generate a sound .
Evan if this circuit require 5V DC for energising the circuit you don’t need an additional transformer or an voltage regulator circuit , because the 5 volts is directly derived from the 230V AC mains supply. Unlike the conventional resistive voltage divider, a capacitive potential divider is used here, which does not radiate any heat and makes the tester quite compact.
I you don’t want to use this infrared remote tester circuit at 230 volts you can modify this circuit and eliminate the voltage regulator part ( and replace it with another 5 volts dc power supply ) .