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AM Radio Circuit using Transistors

This article show how make AM Radio Circuit using Transistors

It use easy parts like transistor, capacitor, resistor and inductor.

Parts are easy to find and good to learn basic radio frequency RF, catch signals and to make sound louder.

Circuit catch medium wave AM signals and changes AM signal to sound and play sound on small 10 ohm speaker.

It is good project for school and people who want to know about radio.

Circuit uses 9V battery to power.

Before making this we need a strong signal place where circuit works best where signal is best.

Circuit Working:

Parts List:

Component TypeValue / DescriptionQuantity
Resistors (All resistors are 1/4 watt unless specified)1M, 39k, 6.8k, 2.2k1 each
Potentiometer 1k1
CapacitorsTrimmer Capacitor 500pF1
Ceramic 0.1µF, 470pF1 each
Electrolytic 47µF 25V , 4.7µF 25V1 each
SemiconductorsTransistors BC547, 2N22221 each
Speaker 10Ω1
Coil: 65 turns of 24SWG enameled copper wire on 100mm long, 10mm diameter ferrite rod; tapping on 5th turn1

Simple AM radio circuit have few parts to work:

Tuned Circuit and Detector Stage:

RF Amplifier Stage:

Audio Output Stage:

Formulas with Calculations:

Here is simple formulas and calculations for AM radio circuit with transistors:

Resonant Frequency of LC Tank:

L1 and C1 pick one AM frequency.

Formula:

f = 1 / (2 × π × √(L × C))

where,

Voltage Gain of Q2 Transistor:

Gain Av for common emitter amplifier:

Av = Rc / Re

where,

Calculate:

Av = 6.8k / 2.2k = 3.1

This gain is enough to drive small 10Ω speaker.

How to Build:

To build a AM Radio Circuit using Transistors following steps are needed to follow to design our own circuit:

Conclusion:

This AM Radio Circuit using Transistors teach how radio works and make signals stronger.

Few parts are needed only to catch and play AM signals.

It is good for school projects and radio hobby.

Circuit is easy to build with no IC needed and is great to learn basics of analog electronics and RF design.

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