My Circuit

Ready Bluetooth solutions are often quite expensive. The cheapest Bluetooth modules that are currently commercially available, there are from the Chinese manufacturer Rayson . The modules BTM-112 (Class 2) and BTM-222 (Class 1) each cost around 15 €. Since the modules are designed for 3.3V supply voltage is required for connection to a 5V system in addition to a 3.3V voltage regulator for 2 level converter (Level Shifter) for the UART signals. In addition, you do not want to give up a status display with LED safely. The price of a module is still all in all about 20 €. The circuit The circuit of the Bluetooth module is designed to operate on a 5V system. As a voltage regulator, a controllable LM317L is used.Similarly, a 3.3V voltage regulator such as the LF33CV could be used. Level converter A level converter (English Level Shifter) is used to adjust signal levels of different voltage levels. A typical example of a level converter is for example a RS232 converter. This converts the 1...

H ere is a circuit that lets you operate your home appliances like lights and water pump from your office or any other remote place. So if you forgot to switch off the lights or other appliances while going out, it helps you to turn off the appliance with your cellphone. Your cellphone works as the remote control for your home appliances. You can control the desired appliance by pressing the corresponding key. The system also gives you voice acknowledgement of the appliance status. Circuit description Fig.1 shows the circuit for cellphone based device control with voice acknowledgement. It comprises microcontroller AT89C51, DTMF decoder MT8870, voice recording/playback device APR9600 and a few discrete components. Microcontroller AT89C51 is at the heart of the circuit. It is a low-power, high-performance, 8-bit microcontroller with 4 kB of flash programmable and erasable read-only memory (PEROM) used as on-chip program memory, 128 bytes of RAM used as internal data memory, 32 individua...