In the case of overhauling the mobile phone of the home appliance remote control, the radio audiometry method is commonly used, but this method cannot judge whether the transmission capability and the frequency are good. Gas Explosion-Proof Motor,Explosion Proof Motors,Gas Explosion Proof Motors,Explosion Proof Electric Motor Yizheng Beide Material Co., Ltd. , https://www.beidevendor.com
I made a high-sensitivity sound and light indication test by using the iron shell shielded finished product receiving head (also available with the new integrated line external line receiving head) and the power supply box and other components on the old outdoor antenna. Device. It can be checked by key to check whether the keys are in good contact with the remote control mobile phone. It can be seen whether the launching capability is strong enough.
In actual production, keep the original power box casing, transformer, power board and red LED part, plus 7805, rectifier, electrolytic capacitor, etc. (such as 5V battery for power supply, this part can be used). The circuit is as shown. 
B1 uses a small radio output transformer, H is a piezoelectric ceramic piece, and can be used as a sound-assisting cavity for the waste plastic film of the No. 1 battery. Other component model parameters are selected as shown.
If the original power supply box has no heat dissipation hole, a hole can be drilled, the piezoelectric piece with the auxiliary sound cavity is fixed near the hole, and the remote control receiving head and the light emitting diode are opened on the outer casing side, and the receiving head is fixed, and the two LEDs can be Out of the shell.
When using, align the remote control mobile phone to the receiving window of the detector and press each button to observe whether the LED1 is illuminated or not.