The idea
I had a room for the machine. There should be a temperature of a certain level, with moisture and cold outside. The electric fireplace and stoves are not for me, there is a lot of firewood, fuel and a lot of energy consumption, with not so much heat output. I looked and purchased an industrial fan, with a minimum of plastic, combustible materials:
Specifications:
- Rated voltage, network frequency, V / Hz __220 / 50;
- Power consumption, kW ____ 1/2 kW;
- Heat output, m3 / hour _____200;
Control
There is a fan heater, now it is necessary to make a smart control and monitoring system. Searching the Internet for a circuit from RK magazine No. 11/2008, “Digital Thermostat”. The design was simple, as for me, with a two-line digital screen. Below is a diagram drawn in SPlan 7.0.
According to the characteristics, the thermostat is able to set the temperature from -25 to + 75 ° С, at a step of 0.25 ° С. In the presets of the menu, you can also set the drop and rise in temperature in steps of 0.1 ° C.
Work with the thermostat is carried out using buttons. The “+” and “-” buttons (S1 and S2) determine the temperature or the fall (rise), the “MODE” button (S3) - setting mode.
In order to set the maintenance temperature, press the S3 button and hold it until “SET TEMPERATURE” lights up on the screen.
Use the S1 and S2 buttons to set the necessary decline (increase).
The next time you press the S3 button, it returns to displaying the current temperature.
Temperature control is carried out using a digital thermometer A1 - DS1820. This is a ready-made item that does not need to be configured. The temperature sensor is made in the form of a separate element, connected to the main unit with a shielded wire with a 3.5mm plug (audio).
In the event of a breakdown, malfunction or a remote sensor not connected, a warning message lights up on the display
The circuit is controlled by the PIC16F628 microcontroller. The clock frequency is organized by ZQ1 quartz with a resonance frequency of 4 MHz.
The fan heater is controlled by the triac VS1 - BT136. The triac is controlled by an MOC3043 optocoupler.I supplemented the fan heater power circuit with an intermediate relay. The relay coil began to play the role of the load of the triac, and parallelized its contacts and connected it into the power supply circuit of the fan heater.
The operational power supply circuit is made on a small hermetic transformer, it has a dual secondary winding, 9V-0-9V, for a rated current of 100mA. The rectifier is made on two diodes VD1 and VD2. If a transformer with one step-down winding, it is necessary to apply a bridge circuit. The controller and display are powered by + 5V via voltage regulator A2 (7805).
To turn off the backlight, pin 16 of the screen can be turned off, or as I set the switch.
Thermostat circuit board, purely my design.
Assembled control board:
There are several pages in the thermostat.lay file.
Housing
The third task is the corps. I chose the Z20. Below is the technology for fitting the case and making holes using templates.
Everything fit in the case. A socket for connecting a switched load is installed.
Files: