Simple Audio Pre-Amplifier


Posted on Feb 7, 2014

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. Here the simple audio mic pre amplifier circuit based on single IC LM358. The circuit is very simple, inexpensive and easy to built. Component Parts List: R1, R3, R4 =


Simple Audio Pre-Amplifier
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10K R2 = 1K R5 = 100K-1M Potensiometer C1 = 0. 1uF C2 = 4. 7uF/16V IC1 = LM358 dual op-amp single supply Mic = Electret Microphone. The following diagram is the schematic diagram of 4 transistors FM transmitter circuit designed by Paul K. Sherby. Components List: R1, R2, R8 = 1K R3 = 100K R4 = 150K R5, R7 = 10K R6 = 220 ohm R9 = 10 ohm P1 = 5K trimpot D1 = 1N4002 Q1, Q2 = 2N3904 Q3, Q4 = 7001, NTE123AP C1. This is the FM transmitter circuit which apply 4 radio frequency stages, that are a VHF oscillator designed around transistor BF494 (T1), a preamplifier designed around transistor BF200 (T2), a driver designed around transistor 2N2219 (T3) and also a power amplifier designed around transistor 2N3866 (T4). A condenser microphone is wired at the input of. Here the short wave AM Transmitter circuit design diagram. The circuit is quite simple and easy to build since it applies only a few electronic components. The primary feature of this transmitter is that it really is absolutely free from the LC (inductor, capacitor) tuned circuit and runs using a fixed frequency of 12 MHz. 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.




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