Build a Variable Frequency NE555 Oscillator (6.8 kHz – 144 kHz) , Best for Tesla Coils

Hi makers!

In this guide, I’ll show you how to build a simple but powerful NE555 oscillator that generates square waves from about 6 kHz to 150 kHz using just a few components.with all neccessery calculations

I originally made this oscillator to drive a Tesla coil, but you can use it for all kinds of projects:

1. Induction heaters
2. Frequency testing
3. DIY motor drivers
4. Audio frequency experiments

No microcontrollers. No programming. (i was build a frequency generator base microcontroller with diffrent modes intrested in that? please check out it on my account :))

NE555 Timer IC ( with its base for soldering ) : Standard 8-pin DIP

Capacitor : 10 nF (marked 103, ceramic)

Resistor : 1 kΩ (fixed, base resistor)

Potentiometer : 10 kΩ (to adjust frequency)

Capacitor (optional) : 220 nF (to filter dc input)

Breadboard or Perfboard

6 –12V Power Supply DC

Wires

Step 1: Power It Up

1. Pin 8 → Connect to +12V (or any power source between 5V and 15V)
2. Pin 1 → Connect to Ground (–)

Step 2: Add the Fixed Resistor

1. Place a 1k resistor between Pin 8 and Pin 7 (this controls charge timing)

Step 3: Wire the Potentiometer

1. Connect one outer leg of the pot to Pin 7
2. Connect the middle leg (wiper) to both Pin 2 and Pin 6 (they should be joined)
3. Connect the other outer leg of the pot to GND

Step 4: Add the Timing Capacitor

1. Use a 10nF capacitor (marked 103)
2. Connect it between Pin 6/2 and Ground

Step 5: Reset and Stabilize

1. Tie Pin 4 (Reset) directly to Vcc (Pin 8)
2. (Optional) Add a 100nF cap between Pin 5 and GND to reduce noise

Step 6: Get Your Signal

1. Take output from Pin 3
2. Connect this to a buzzer, or the gate of a MOSFET to test it

This is a basic astable oscillator configuration:

1. Pin 7 discharges the capacitor through the 10k potentiometer.
2. Pin 6 and 2 sense the voltage across the capacitor.
3. As the pot is turned, the charge/discharge time changes, altering the frequency.

With:

1. C = 10nF
2. R1 = 1kΩ
3. R2 = 0Ω to 10kΩ

You get frequencies from: ≈ 6.8 kHz to 144 kHz (Check the calculation paper for detailed calculation)

If using a perfboard, keep all leads short to reduce noise.

Mark the potentiometer’s start/mid/end to easily tune your desired frequency.

You can add a 220 nF capacitor at input of voltage (optional but recommended).

Power up your circuit.

Connect a piezo buzzer or small speaker to the output (pin 3) to hear the tone.

Turn the potentiometer slowly—you’ll notice a change in pitch.

If you have an oscilloscope or frequency meter, verify the output waveform and frequency.

This oscillator is incredibly versatile. With just a 555 timer, one cap, and a pot, you can generate a wide range of frequencies and use it in sound experiments, flashing LEDs, or even power driver circuits. Plus, it’s fun to hear electronics sing! :)