Here is the AM Radio receiver circuit diagram based on old single IC MK484. Components List: R9, R10_________ 6R8 R6_____________ 100R R3_____________ 1K R1_____________ 4K7 R7_____________ 5K6 R4_____________ 10K R2_____________ 100K R5_____________ 150K R8_____________ 820K Pot_____________ 10K log pot Coil & ferrite bar set C7______________ 470p ceramic C, C4, C5, C6_____ 470nF monoblock C2______________ 100nF… Read More »
This circuit is a powerful three stage, 9V FM transmitter (Tx) with a range of up to 1 kilometer in the open. It uses an RF transistor in its output stage and two BC547″s for the first two stages. Distance of trans-mission is critically dependent on the operating Conditions (in a building or out on… Read More »
Here is the wailing alarm siren circuit diagram: Components List: R1,R5___________ 4.7K R2______________ 47K R3______________ 10K R4______________ 100K Rx______________ *see text C1,C4__________ 100uF/25V, electrolytic C2,C3__________ 0.01uF (10nF), ceramic T1_____________ 2N3702 (NTE159, TUP, etc.) IC1,IC2________ LM/NE555, MC1455P, etc LS_____________ Loudspeaker
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 a simple audio pre-amplifier circuit using single transistor 2N3904. This easy circuit provides good gain to weak audio signals such as electret microphone. Use it in front of an RF oscillator to make an RF transmitter that’s very sensitive to sound. Power supply used for this circuit is wide range from 3VDC to… Read More »
Here the simple and low cost FM transmitter circuit. The frequency range of this FM transmitter should be about 89MHz – 109MHz. Output power is about 9mW at 9V. Components List: Resistors: R1, R6 : 12K R2, R4 : 100K R3 : 22K R5 : 1K R7 : 100R Capacitors: C1 : 10uF/25V C2 :… Read More »
This a two station intercom. It uses two wires to run between each intercom unit. Each is self contained with its own battery, speaker, microphone and amplifier circuit. An LM386 audio power amplifier is used. It is widely available, used a minimum of external parts and is well suited to battery operation. It will give… 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: