DIY Wireless Digital Thermometer For Multiple Sensors

This wireless digital thermometer project uses a hardware-based scanning and telemetry architecture rather than a programmable microcontroller. At the core of the transmitter circuit, a 3-bit binary counter systematically sequences through up to eight temperature sensors. As the counter steps through each channel, the analog voltage representing the temperature is captured and converted into a digital byte using an 8-bit Analog-to-Digital Converter (ADC). This digital data, along with channel identification signals, is fed into a parallel-to-serial encoder to format the bitstream for transmission. The serialized data modulates a 433MHz Ultra High Frequency (UHF) RF transmitter module using Amplitude Shift Keying / On-Off Keying (ASK/OOK) modulation, which then broadcasts the data through the air via radio waves. On the receiving end, the paired 433MHz RF receiver module captures the incoming ASK/OOK radio signals and passes them to a data decoder. The decoder converts the serial data back into a parallel format. Finally, an 8-bit Digital-to-Analog Converter (DAC) transforms the digital temperature values back into corresponding analog signals, which can be observed and verified using a digital multimeter. Supporting resistors, capacitors, and power supply components ensure stable voltage regulation and signal integrity throughout both the transmitting and receiving stages.