Posted on Wednesday, July 27, 2011 • Category: FM Transmitters
A very good 1 watt fm transmitter circuit, very easy to build circuit. It has 4 transistors, one is a very stable oscillator, followed by a buffer stage to prevent frequency variation when you adjust the transmitter. Next is a resonance stage and the final stage built with a minimum 1W transistor which must have a heatsink. You must use a LM7805 stabilizer for the oscillator diodes and one LM7809 for powering up the T1 oscillator stage. This will give you a very stable transmitter frequency.
Posted on Monday, July 25, 2011 • Category: FM Radio / Receivers
This is the most simple fm radio receiver with good performances that works great even if the sensitivity is not too high. The working principle of this fm receiver may seem a little unusual. It is made of an oscillator (T2 and T3) that is synchronized with the received frequency of T1. This transistor works as a broadband preamplifier in VHF range.
Posted on Friday, July 22, 2011 • Category: FM Radio / Receivers
This simple fm radio receiver circuit consists of a regenerative rf stage, TR1, followed by a two of three-stage audio amplifier, TR2 to TR4. In some areas 3 stages of audio amplification may not be necessary, in which case TR3 and its associated components can be omitted and the free end of capacitor C5 connected to the collector of TR2.
Posted on Tuesday, July 19, 2011 • Category: Antennas
This is a low cost fm antenna booster that can be used to listen to programs from distant FM radio stations clearly. The antenna fm booster circuit comprises a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570 (C2570).
Assemble the circuit on a good-quality PCB (preferably, glass-epoxy). Adjust input/output trimmers (VC1/VC2) for maximum gain.
Posted on Monday, July 18, 2011 • Category: LED
Here's a simple circuit that flashes an LED on and off. This circuit uses the 555 timer in an Astable operating mode which generates a continuous output via Pin 3 in the form of a square wave. This turns the LED (D1) on and off. The speed at which the LED (D1) is turned on and off is set by the values of R1 and R2.
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