This is the circuit diagram of a voice operated relay. It similar with sound activation switch circuit which will turn on and turn off (connect and disconnect) the switch depending on the sound input. The output switch of this circuit is act by a relay. Components list: R1, R7 : 1K R2, R4, R8 :… Read More »
This is an 250mW RF power amplifier circuit project. This circuit is designed to amplify the output of about 7mW wide band FM transmitters to a final level of about 250mW. General purpose 12V DC power supply can be used to operate this RF amplifier circuit. Schematic Diagram: Components List: R1 ____________________ 10R R2 ____________________… Read More »
This is a sound activated switch circuit. It’s will turn on and turn off based on a loud sound such as clapping your hands. You can adjust the sensitivity (how loud of a sound will activate the circuit) from a pin drop to a Mack Truck Horn. Very practical for a variety of projects. Add… Read More »
The following is 4 x 25W quad audio amplifier circuit (amplifier with four inputs and four outputs) based TDA7381. This amplifier is designed for car audio system, but you can also use this circuit for other purposes. This circuit has a design very simple and very easy to build. Schematic diagram: If properly layouted and… Read More »
The following scheme is a courtesy light circuit you can use to delay an electronic device to be disabled. For example, you can connect this circuit to the lamp in your room. When you turn off the lamp with a switch on the circuit, the lamp will remain lit in a certain period of time,… Read More »
This is the circuit diagram of mini FM receiver that build based on single FM IC TDA7012T. Components List: R1 = 8kΩ2 R2 = 10kΩ R3 = 390Ω C1,C3 = 10nF C2,C6,C9,C16 = 100nF C4 = 33pF C5 = 25pF trimmer (Murata type TZB4Z250AB10R00) C7,C10 = 1nF5 C8 = 820pF C11 = 1nF C12 =… Read More »
This is a 12VDC to 9VDC converter circuit. You may use this DC to DC stepdown converter circuit if you have fixed 12V power supply / battery, but you need 9V power supply for your electronic devices. Scheme Diagram: Components List: R1________ 560 ohm, resistor C1________ 1000uF/16V, Electrolytic capacitor C2________ 100uF/16V, Electrolytic capacitor C3________ 330nF,… Read More »
This is a very easy and simple LED flasher with only three components: a flasher IC LM3909, a LED indicator and an electrolytic capacitor. The supply voltage is 1.5V, so it can be operated using a 1.5V battery which can be easily found on market. Component list: LED1 _________ Red LED C1 ___________ 100uf/16V IC1… Read More »
This is the circuit diagram of 80W power audio amplifier based on power IC LM12. The circuit kit is sold at electronic part/component store, the design is proven to be valid and work. This amplifier use dual polarity power supply to operate. Here the Amplifier Circuit Diagram: Here the PCB layout: