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50Hz Square Wave Generator Circuit using Transistors

Last updated on 20 December 2025 by Admin-Lavi Leave a Comment

This article is for 50Hz Square Wave Generator Circuit using Transistors.

Two transistors switch ON and OFF one by one.

Outputs blink opposite time.

No IC is used only simple parts are required.

We can change resistor or capacitor to change speed.

This circuit is good to learn basic oscillator working.

Circuit Working:

50Hz Square Wave Generator Circuit  Diagram using Transistors

Parts List:

ComponentsValueQuantity
Resistors10k 1/4 watt2
1k 1/4 watt2
Preset 220k2
CapacitorsCeramic 0.1µF2
SemiconductorsNPN Transistor BC5472
Battery / Power Supply 12V DC1

When power supply is ON the circuit start by itself.

Due to small difference, one transistor turn ON first.

Its output become active and other transistor stays OFF.

Capacitor connected to ON transistor start charging.

After some time the capacitor discharge to other transistor base.

This make second transistor ON and first transistor OFF.

Now second capacitor start charging.

After delay, it discharge back and turn first transistor ON again.

This switching continue again and again.

Because of this, square wave output generate and both outputs work opposite time.

How to Build:

To build a 50Hz Square Wave Generator Circuit using Transistors follow the below connection steps:

  • Assemble all parts as per circuit diagram.
  • Emitter pin of Q1 and Q2 both connect to ground.
  • Collector of Q1 connects with R1 and C1.
  • Collector of Q2 connects with R4 and C2.
  • Base of Q1 connects with C2 and VR1 through resistor R2.
  • Base of Q2 connects with C1 and VR2 through resistor R3.
  • R1 and R4 connect from +12V to collectors.
  • VR1 and VR2 connect from +12V to transistor bases.

Conclusion:

This is simple and low cost 50Hz Square Wave Generator Circuit using Transistors.

Only basic parts used and circuit is easy to make and understand.

Output frequency depends on resistor and capacitor.

By changing RC value, different frequency we can get.

References:

Circuits that can generate a square wave current

Filed Under: Oscillator Circuits, Transistor Circuits

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

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