2KM Long Range FM Radio Transmitter

This long-range FM radio transmitter has an additional RF power amplifier stage, after the oscillator stage. The extra RF power amplifier used to strenght up the power output to become 200-250 milliwatts. With a great matching multi-element Yagi antenna or 50-ohm ground—plane antenna, this transmitter can give great good signal strength up to a distance… Read More »

Portable 230V Lamp Flasher

This is a portable, 230V high-power incandescent electric lamp flasher circuit diagram. It is actually basically a double flasher (alternating blinker) which could manage two different 230V AC loads (bulb lamps L1 and L2). The circuit is completely transistorised and battery-powered. The free-running oscillator circuit is realised working with two low-power, low-noise transistors T1 and… Read More »

Electronic Horn

This is an easy, low cost and easy built circuit of an electronic horn which is designed close to quadruple op-amp IC LM3900 (IC1). IC LM3900 has four independent operational-amplifiers (A1 through A4) having a large output voltage swing. It is able to operate at up to 32V DC. The 1st op-amp (A1) is designed… Read More »

Three Stage 9V FM Transmitter

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 »