Sammer has noticed about his latest project called liquid supply system. You can see a good example of such device when filling petroleum. It pours exact amount of it. The solution is pretty simple – it is based on time value rather than debit counter. So before usage, it needs a reference value which is taken by measuring 100% value. This is done by running pump as long as desired amount is pumped. Say its one litter than its 100%. Once the value is stored you can pour like 5 litters by setting value of 500% on LCD and starting the pump motor. Once liquid is poured, it stops automatically.

This by far not the most accurate way of doing this, but if you get right reference value and pump flow is constant, then it serves pretty good. The most attractive thing here that it is setup is simple – microcontroller, and motor relay. No real measuring is done.

In order to maintain comfort in the room you need temperature controller. The best results are achieved with heater and cooler working together. Sameer have put quite simple room temperature controller using AT89S52 microcontroller. These microcontrollers are based on industry-standard 80C51 instruction set.

Controller reads temperature from same reliable Ds1820 temperature sensor. While microcontroller doesn’t have internal EEPROM there is an external AT24C02 IC used to store preset values. It is interfaced using I2C communication protocol. Also there is a standard alphanumeric LCD driven in 4-bit mode where temperature and status messages are displayed. Temperature threshold values can be changed using couple push buttons. Unit has two relay switches where one controls heater and another cooler. Depending on current temperature value the relays can be switched differently. For instance is there is too hot in the room, cooler is on and vice versa, if its too cold, then heater is on and cooler is off.

Sameer Guptadesigned a robust water tank filling controller. First circuit is based on simple CMOS logic which detects when water fills the tank using two conductive electrodes. But he wanted to have more control, so he made another version which is based on AT89C2051 microcontroller.

Controller does pretty same thing as predecessor, but have more features like blinking LED indicator, sound alarm and of course possibility to add more features.

Lux meters are common devices among photographs or lighting specialists  – anywhere where illumination level is important parameter. Following lux meter developed by Sergei is capable of measuring illuminance in the range 0.025 – 99999 lux. He used MAX44007 sensor which is already factory calibrated.

He’s chosen a C8051F304 microcontroller from Silicon Laboratories. It talks to lux sensor via I2C interface and also updates 128×32 graphical LCD. Lux meter is only a 30x60mm size and is powered by single CR3032 coin cell.