am transmitter schematic | Electronic Schematic Diagram https://electronicscheme.net Schematic Diagram & PCB Design Mon, 15 Dec 2014 03:36:49 +0000 en-US hourly 1 https://i0.wp.com/electronicscheme.net/wp-content/uploads/2017/05/cropped-transparent_text_effect.png?fit=32%2C32&ssl=1 am transmitter schematic | Electronic Schematic Diagram https://electronicscheme.net 32 32 129969089 Mini MW Transmitter https://electronicscheme.net/mini-mw-transmitter/?utm_source=rss&utm_medium=rss&utm_campaign=mini-mw-transmitter https://electronicscheme.net/mini-mw-transmitter/#respond Mon, 08 Nov 2010 03:36:50 +0000 http://electronicscheme.net/?p=605 The following is a circuit of a simple AM transmitter. This circuit is available in kit form and can work well since the kit available […]

The post Mini MW Transmitter first appeared on Electronic Schematic Diagram.]]> The following is a circuit of a simple AM transmitter. This circuit is available in kit form and can work well since the kit available on market.

Mini MW Transmitter circuit diagram

This circuit uses a combination of transistors SA101 and SA103, as the modulation signal amplifier.

Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz and in North America an extended MW broadcast band goes from 535 kHz to 1705 kHz.

Wavelengths in this band are long enough that radio waves are not blocked by buildings and hills and can propagate beyond the horizon following the curvature of the Earth; this is called the groundwave. Practical groundwave reception typically extends to 200-300 miles, with longer distances over terrain with higher ground conductivity, and greatest distances over salt water. Most broadcast stations use groundwave to cover their listening area.

The post Mini MW Transmitter first appeared on Electronic Schematic Diagram.]]> https://electronicscheme.net/mini-mw-transmitter/feed/ 0 605 Mini AM Transmitter https://electronicscheme.net/am-transmitter/?utm_source=rss&utm_medium=rss&utm_campaign=am-transmitter https://electronicscheme.net/am-transmitter/#comments Sat, 06 Jun 2009 12:51:10 +0000 http://electronicscheme.net/?p=112 This is the simple and low cost AM transmitter schematic diagram built using transistor BC109C. The circuit is in two halfs, an audio amplifier and […]

The post Mini AM Transmitter first appeared on Electronic Schematic Diagram.]]> This is the simple and low cost AM transmitter schematic diagram built using transistor BC109C.

AM Transmitter circuit diagram

The circuit is in two halfs, an audio amplifier and an RF oscillator. The oscillator is built around Q1 and associated components. The tank circuit L1 and VC1 is tunable from about 500kHz to 1600KHz. These components can be used from an old MW radio, if available. Q1 needs regenerative feedback to oscillate and this is achieved by connecting the base and collector of Q1 to opposite ends of the tank circuit.

The 1nF capacitor C7, couples signals from the base to the top of L1, and C2, 100pF ensures that the oscillation is passed from collector, to the emitter, and via the internal base emitter resistance of the transistor, back to the base again. Resistor R2 has an important role in this circuit. It ensures that the oscillation will not be shunted to ground via the very low internal emitter resistance, re of Q1, and also increases the input impedance so that the modulation signal will not be shunted. Oscillation frequency is adjusted with VC1.

Q2 is wired as a common emitter amplifier, C5 decoupling the emitter resistor and realising full gain of this stage. The microphone is an electret condenser mic and the amount of AM modulation is adjusted with the 4.7k preset resistor P1. An antenna is not needed, but 30cm of wire may be used at the collector to increase transmitter range.

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