Circuits

If you still have an old computer, the problem is to connect to it modern mouse may be familiar to you. Old mechanical mouse, sooner or later come into disrepair - cable wear, buttons do not work, etc. In general, modern laser mouse is usually much nicer than the devices of the last century

Because the serial mouses are no longer produced, then the for PC without a PS/2 port is still two options: adapt the PS/2 or USB mouse. With PS/2 mouse everything is much easier - this protocol can be implemented in almost any microcontroller, such as ATMega8.

The adapter is built on ATMega8 microcontroller and uses MAX232 to match the TTL signal levels with a serial port levels. The microcontroller receives data from the PS/2 mouse and transmits them via the UART.

This device allows to reduce the noise from cooling fan. It turn off the fan or reduces the rotation speed depending on the temperature of the radiator. Also the device beeps when temperature exceeds a threshold. There are two variants of device for fans of different power.

The first variant is designed to control 12-volt computer fan, and has been fully implemented on the SMD-elements:

This LED "icicle" made from mainly blue LEDs. This device can serve as Christmas present or New Year's ornament. The "icicle" can be transformed into a "candle" if to use red and yellow LEDs and to change accordingly its external design. As the body I used two fur-tree toys: transparent plastic icicle and one-half of the Christmas ball. LEDs are placed in the first and second placed the microcontroller board.

It's a simple doorbell that can play melodies and audiorecords from I2C flash-memory chip. The device has two parts - digital and analog. The digital part used the microcontroller AT89C2051 and flash-memory AT24C256.