Presented here is an Arduino-based automatic fish feeding system for an aquarium. Feeding the fish is a daily task, which can become a problem if you are out of station for more than a day. This dispenser just needs to call a cellphone number followed by another number to perform a particular task, like turning on the motor to feed the fish in the aquarium. This project requires two cellphones, one for making the call and another for receiving it. Circuit and working The block diagram of the automatic food dispenser for an aquarium is shown in Fig. 1. The circuit diagram of the same is shown in Fig. 2. It consists of Arduino Uno board (Board1), DTMF decoder MT8870 (IC1), 5V voltage regulator 7805 (IC2), npn transistors BC547 (T1) and 2N2222 (T2), 5V relay (RL1), 12V DC motor and a few other components. Fig. 1: Block diagram of automatic food dispensing system Fig. 2: Circuit diagram of automatic food dispenser for aquarium DTMF Dual-tone multiple frequency (DTMF) is a signalling system...

This converter is inexpensive and quick to build, it is nothing more than a DC / DC converter, its use is for USB sockets or any other device that needs a stabilized voltage 5 Volts and a maximum current of 2 amps. With this power converter, you insert a voltage from 6 Volts to 24 Volts and have a regulated output of 5 Volts per 2 Amperes. That is, you can use a car or motorcycle battery or your vehicle's cigarette lighter as power, and you will have an outlet to charge your cell phone, camera, etc. DC / DC converter for USB jacks The circuit is very simple, and you may have already seen it in some project here on the site, the circuit uses only five components, a 7805 positive voltage regulator integrated circuit, a TIP42 transistor, a 5 Ohm resistor and two disk capacitors or polyester, one of .33 and the other of .1 or 330 and 100 nF. The capacitors are filters and accompany the voltage regulator 7805. This converter works perfectly, as long as you respect a number of devices co...