This is a 35.3 to 10.7 MHz converter circuit. It converts the 35.3 MHz signal coming from a VHF/UHF tuner down to an FM tuner to decode the TV audio in FM quality. The IC being used (TBA120) is one of the most common components in radio and TV circuits. Although it was designed as an RF amplifier and FM demodulator, it can also be used for many other applications.

This analog switch circuit is designed to switch on or off and analog line. it consists of two analog switches in IC form that are controlled by two pushbutton switches. In standby mode the voltage at the control pins of the analog switches is low.

This NiCad baterry charger circuit schematic can charge 6 volts as well as 12 volts NiCad batteries. It uses a transformer which can deliver 4 to 5 A current between 12.6 and 15 V. Ordinary chargers select the charging voltage through a swith but the circuit featured here uses an automatic current regulator.

This FM radio tuner is the right circuit for hobbyists who want to build their own tuners instead of buying a “plug-n-play” finished product. The fm tuner circuit is designed with only 3 transistors. The amplification is around 40 dB. The first transistor works as an RF amplifier. The second transistor is the mixer.