Computer Microphone

This circuit was submitted by Lazar Pancic from Yugoslavia. The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to 600 ohms. Lazar has adapted the sound card to use a common electret microphone using this circuit. He has made a composite amplifier using two transistors. The BC413B operates in common emitter to give a slight boost to the mic signal. This is followed by an emitter follower stage using the BC547C. This is necessary as the mic and circuit and battery will be some distance from the sound card, the low output impedance of the circuit and screened cable ensuring a clean signal with minimum noise pickup. original article soruse: eleccircuit.com

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One Chip AM/FM Radio with Audio Power Amplifier

Description: The integrated circuit TDA1083 includes, with exception of the FM front end, a complete AM-/FM-radio-circuit with audio power amplifier. An internal Z-diode stabilizes the supply voltage at VS 13 V, which allows with the aid of a resistor and a rectifier, the circuit to be driven by a higher external supply voltage. Features: Large supply voltage range VS = 3 to 12 V High AM-Sensitivity Limiting threshold voltage Vi = 50 V Audio output power P0 = 0.7 W AFC-connection for VHF-tuner AM-FM switching without high frequency voltages Applications: AM-/FM- and audio-amplifier Circuit Diagram: Circuit diagram for One Chip AM/FM Radio with Audio Power Amplifier Datasheet for TDA1083: Download

2 x 15 W stereo Bridge Tied Load (BTL) audio amplifier

General description: The TDA8946J is a dual-channel audio power amplifier with an output power of 2 × 15 W at an 8 Ω load and a 18 V supply. The circuit contains two Bridge Tied Load (BTL) amplifiers with an all-NPN output stage and standby/mute logic. The TDA8946J comes in a 17-pin DIL-bent-SIL (DBS) power package. The TDA8946J is printed-circuit board (PCB) compatible with all other types in the TDA894x family. One PCB footprint accommodates both the mono and the stereo products. Features: Few external components Fixed gain Standby and mute mode No on/off switching plops Low standby current High supply voltage ripple rejection Outputs short-circuit protected to ground, supply and across the load Thermally protected Printed-circuit board compatible Circuit Diagram: Circuit Diagram for 2 x 15 W stereo Bridge Tied Load (BTL) audio amplifier PCB layout: PCB layout TDA8946 Datasheet for TDA8946J: Download

200W Hybrid Audio Amplifier Circuit

200W Hybrid Audio Amplifier Circuit - c onnecting two TDA2030 thru cheap power transistors we can create a amplifier wich can deliver a higher power. With the components value from the schematic the total amplifier gain is 32 dB. The speaker can be 2 ohm instead of 4 ohm if we use the TIP transistors. TDA 2030 is produced by SGS Ates and is a complete audio amplifier. AB class of the final amplifier cand deliver up to 14W on 4 ohm at a +-14V power supply. With a proper designed power supply this audio amplifier can output 200W. Active components: IC1, Ic2 TDA 2030 T1, T3 = BD 250, TIP 36 T2,T4 = BD 249, TIP 35 D1 … D4 = 1N4001 200W Hybrid Audio Amplifier Circuit

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