Homemade simple automatic message machine

Single chip microcomputer STM32L151CCU6

RF cable can be customized for other specifications

6.3V220UF Volume: 5X8 own factory direct sales - solid capacitor - patch aluminum

Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ) 7.5PF 10PPM 20PPM 30PPM

First, the component selection

C1 selects the leakage current to be particularly small; the relay selects the small reed relay with working voltage ≤6V, pull-in current ≤15mA, contact voltage >220V, contact current >0.1A; resistance R1<500kΩ.

Second, the working principle

When using, press the recorder recording button, K1 closes, and put the words "The owner is not at home, please ring the doorbell, and there is something for you to record for two minutes" on the door. If you find that the LED light is on, it means that the guest has come, rewind the recording, you can know the guest message, but don't forget to break K1 once, otherwise the LED light will always be on.