1.2 General design of the STC 1000
The STC-1000 consists of two PCB's, the main board and the display board. They are held together by the solder joints that also passes the signals between them.
| Pin number | Description |
|---|---|
| 1 | Thermistor (Sensor 1) |
| 2 | ICSPCLK / Thermistor (Sensor 2) |
| 3 | ISCSPDAT / Buzzer |
| 4 | GND |
| 5 | GND |
| 6 | Vcc |
| 7 | Vcc |
| 8 | Vcc |
| 9 | Heating relay |
| 10 | Cooling relay |
| 11 | N/C |
| 12 | nMCLR |
| 13 | GND |
| 14 | GND |
| 15 | GND |
| 16 | GND |
The main board has a small (well... relatively speaking) PCB mounted transformer (the brown rectangular thingy in the image above) that converts mains power to 12VAC (the only difference between the 110VAC and 220VAC version is this transformer). This is then rectified and I assume smoothed with a capacitor to give a 'dirty' 12V power bus. This then feeds a linear regulator for a 'clean' 5v power bus.
The board also houses a piezo buzzer (the round black thingy in the PCB image), the two JQC-3FF relays (the two rectangular black things above the transformer), transistors (and flyback diodes) to drive the relays from the 12v bus and the screw type connection terminals in the back.
It also has the much needed programming header.
The display board has the LED display, the four buttons and the Microchip PIC16F1828 MCU on the bottom of the PCB.
