FM Transmitter Circuit using Transistors

FM Transmitter using Transistors
FM transmitters are one one of the basic RF circuit you could easily build at home and of course you can even play with these kinda circuits. The above circuit is one of the simplest and most basic FM transmitter you could build. Even though this circuit supplied with only 5V it is capable of covering the range of around 300 meters.

Temperature controlled DC motor using PIC 16F877A

Temperature Controlled DC motor
You might have come across several applications where we need to control a specific device based on analog parameter. This Embedded system works in a similar concept where we are about to control the speed of a DC motor using based on the external temperature. The rise in temperature will result in increase in speed of the motor and vice versa. These type of systems can generally be used to maintain temperature of a room or object automatically.

Working of IC ULN2803

IC ULN2803 Pin Diagram
ULN2803  is a High voltage, high current Transistor Array IC used especially with Microcontrollers where we need to drive high power loads. Thic IC consists of a eight NPN Darlington connected transistors with common Clamp diodes for switching the loads connected to the output. This IC is widely used to drive high loads such Lamps, relays, motors etc. It is usually rated at 50v/500mA.