Vermes
Advanced Member level 4
Unitra Pionier RE 105 is a popular radio clock manufactured in the 80s. The construction has a good FM tuner with a voltage tuned head and a programmer for three channels on FM and one on AM.
This project is a processing of an old radio clock. The old tuner was removed. Then a new transformer 5/12V was applied to the power supply. Synthesis system TSA6057 works with the head from a wrecked car radio. That head is equipped with stereophonic receiver, MPX signal output and very good sensitivity.
RDS decoder was based on the system of preprocessor SAA6588. Its main advantage is that ready data can be received via I2C. Grouped data can be displayed. It can take place in an interrupt forced by DAVN output of the preprocessor. Used information: PS (name of the program), RT (Radio-Text) and CT (Clock-Time). Information from CT can be additionally verified and then stored in RTC (PCF8583), then hour is read from it and displayed. In addition, batteries maintain the device. Decoder can cause some distortions, so it should be shielded.
Radiotext is hardly visible on LCD display, so it is better to use VFD with brightness four steps regulation. Only the strongest and the weakest used save both screen and eyes. Photoresistor is in the top of the housing (picture). Additionally, the screen was dimmed by film for windscreen sticked on it.
Then you have to adapt a remote control to the device. It can be an IR remote control (picture), which allows you to turn on and out the device, switch programmed channels, volume adjustment and control (on/off) the alarm.
Volume adjustment was based on a chip TDA8425. The potentiometer was replaced with an encoder equipped with a pressed axle which allows for manual turning on and off (sleep mode).
The whole is powered by microcontroller Atmega8515. The device can remember up to 20 channels in the EEPROM.
Analog clock operates autonomically and the alarm can be activated even if it is not plugged in. Power supply is R14 battery. The clock is backlit with 3 SMD LEDs.
Pictures:
Video:
Link to original thread (useful attachment) – "Tuning" radiobudzika UNITRA Pionier RE 105