• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

Circuit Ideas for You

Get free circuit ideas online.

  • Home
  • Privacy Policy
  • About
Home » Simple FM Microphone Transmitter Circuit

Simple FM Microphone Transmitter Circuit

Last updated on 23 July 2025 by Admin-Lavi Leave a Comment

FM mic transmitter is small device.

It changes sound from mic into radio signal.

FM radio can hear it in short distance.

This Simple FM Microphone Transmitter Circuit uses one NPN BC547 transistor.

Even it is small it can send FM signal pretty far.

Circuit Working:

Simple FM Microphone Transmitter Circuit Diagram

Parts List:

CategoryDescriptionQuantity
Resistors330Ω 1/4 watt1
4.7k 1/4 watt1
CapacitorsCeramic 0.001μF1
Ceramic 22pF1
Trimmer capacitor1
SemiconductorsBC5471
Inductor coil 0.1uH1
Antenna1
Electret mic1
Battery 9V1

This FM transmitter circuit take voice from small mic means condenser mic.

If we want to send direct audio then remove mic and give audio at base and R1 point.

To make signal go more far then use long wire or antenna.

Trim capacitor C2 and coil L1 set the FM signal frequency and always use free non-commercial FM band.

With this simple FM transmitter we can send sound on FM radio.

Easy points about this circuit:

One Transistor Only:

It is for very simple use only with one transistor.

Changeable Frequency:

By adjusting C1 and L1 we can change frequency from 50MHz to 160MHz where FM radio can catch it.

Mic Input:

Mic take sound and circuit makes signal.

Low Power Use:

Use small battery power with only few parts inside.

Not as strong or clear as advanced circuits but is good for beginners to learn FM transmitter basics.

Formulas:

We can find the exact working frequency of FM transmitter using this formula:

f = 1 / (2π√(L * C))

where:

  • f is frequency in hertz Hz
  • L is coil value in henrys H
  • C is capacitor value in farads F

Note:

This formula works for perfect circuit.

In real life small extra things like wire effects or part changes can change result a bit.

Trimmer capacitor C2 is used to set frequency inside FM range with 88 MHz to 108 MHz.

Better to use full circuit diagram with all part values and tips for tuning when building FM mic transmitter.

How to Build:

To build a Simple FM Microphone Transmitter Circuit follow the below mentioned steps for connections:

  • Gather all parts like in circuit diagram.
  • Connect collector of transistor Q1 to +9V battery through coil L1.
  • Connect base of Q1 to (+) side of electret mic.
  • Connect (–) side of mic to ground.
  • Connect emitter of Q1 to ground through resistor R2.
  • Connect R1 and C1 from +9V to ground.
  • Connect capacitor C2 between +9V and collector of Q1.
  • Attach antenna after C2.
  • Also connect C2 between collector of Q1 and point between emitter and R2.

Important Notes:

  • FM mic transmitters must follow our countries radio rules.
  • We must use only allowed power and frequency.
  • Ask the local radio department for legal information.

Conclusion:

This Simple FM Microphone Transmitter Circuit is great for learning how FM signals work.

But always be safe and follow the local radio laws.

References:

FM Microphone Transmitter Circuit

Filed Under: Transmitter Circuit

About Admin-Lavi

Lavi is a B.Tech electronics engineer with a passion for designing new electronic circuits. Do you have questions regarding the circuit diagrams presented on this blog? Feel free to comment and solve your queries with quick replies

Previous Post: « How to Design Crystal Oscillator Circuit
Next Post: Simple Door Open Alarm Circuit using Reed Switch »

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar




Categories

  • Alarm Circuits (34)
  • Amplifier Circuits (67)
  • Arduino Projects (59)
  • Audio Circuits (98)
  • Automobile Circuits (19)
  • Battery Charger Circuits (49)
  • Free Energy (13)
  • Heater and Temperature Controllers (10)
  • High Voltage (1)
  • Indicator Circuits (41)
  • Inverter Circuits (14)
  • LDR Circuits (17)
  • LED and Lamps (118)
  • Meters and Testers (29)
  • Motor Controllers (18)
  • Oscillator Circuits (34)
  • Power Supply Circuits (93)
  • Remote Control Circuits (7)
  • Security and Protection (26)
  • Sensors and Detectors (98)
  • Solar Circuits (17)
  • Timer Circuits (31)
  • Transistor Circuits (57)
  • Transmitter Circuit (14)
  • Tutorials (5)
  • Water Level Controller (4)

Recent Posts

  • Smart Energy Meter Circuit with Arduino UNO
  • LED Binary Counter Circuit
  • Audio Spectrum Analyzer Circuit using IC MSGEQ7
  • RGB LED Color Control Circuit with LDR and Arduino
  • Arduino Based GPS Digital Clock Circuit

Recent Comments

  1. Admin-Lavi on Constant Voltage, Constant Current Battery Charger Circuit
  2. Bill on Constant Voltage, Constant Current Battery Charger Circuit
  3. Admin-Lavi on Long Range FM Transmitter Circuit (2km)
  4. Sina on Long Range FM Transmitter Circuit (2km)
  5. Admin-Lavi on Long Range FM Transmitter Circuit (2km)

Copyright © 2025 | New Circuit Ideas