Aquarium controller of own construction

[Vermes]

Main functions of the controller

• switching on and off the light
• simulation of sunrise and sunset by smooth lighting and extinguishing halogens 12V controlled by PWM
• measurement of pH and on the basis of that measurement – CO2 solenoid valve control
• adding and changing water (solenoid and a pump pumping old water)
• dosing of liquid fertilizers using the windscreen washer pumps 12V
• temperature measurement and controlling the heater

The most important element of the controller is Atmega32. The rest can be divided in few modules. The controller is powered from an UPS accumulator (UPS also powers the circulation pump in the aquarium) with 12V. LM7805 stabilizes the voltage on the level of 5V (adequate to supply elements of the controller). Two ULN2803 are responsible for activation of the relays. The clock is PCF8583 which communicates with Atmega32 via I2C. Temperature of the water is measured by LM35DZ. The last module is signal amplifier from electrode to measurement of pH, based on TL074. All the relays are on a separate board. They switch on the light, the heater, CO2 solenoid, water solenoid, pumps dosing liquid fertilizers etc. There is also IRF640 along with the heat sink and ventilator on the board with relays module. It controls the halogens simulating sunrise and sunset.
The first picture shows the front panel of the controller, next two – the motherboard from the top and bottom, and the last – relays module with transistor IRF640.




Link to original thread – Sterownik akwarystyczny