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What is a Slayer exciter circuit (Tesla Coil) ??

posted Sep 20, 2017, 8:28 AM by Rohit Bhaskar   [ updated Sep 20, 2017, 8:33 AM ]

This post is dedicated to people who have a taste for theatrics. Why? Because this circuit literally performs magic!! By the time you finish reading, you’ll be able to glow light bulbs wireless and create music out of thin air.

Some concepts first:

Slayer exciter circuit is the solid state equivalent of a Tesla coil. It is a basic RF oscillator circuit with a step-up transformer at the collector of the transistor. The circuit at the secondary of the transformer is formed by the parasitic capacitor that is present between the transformer secondary terminal and the ground. Slayer exciter circuits have the specialty of tuning themselves automatically to the resonant frequency,unlike classical tesla coils,which need to be manually tuned. This makes them very easy to make, even with a little ‘jugaad’, and expect good results. Hence,the circuit is very popular among the hobbyist community due to its easy circuit and awesome applications. Now,let’s  dive into it’s working with the help of an example circuit.

The working:

-   5 to 18 volts is fed into the circuit, a resistor (R1) is placed before the Base pin of the transistor in order to limit the amount of current the pin receives. If too much current is allowed into the Base pin the transistor can produce excessive heat and fail.

-   One end of the secondary (L2) is connected to the Base pin of the transistor in order to feed it with oscillations. The two diodes (D1 and D2) prevent the oscillations from going directly to ground. (Learn more about oscillations and why they're important, below).

-   When the Base receives a little bit of current, it closes the circuit and electricity is allowed to flow through the primary coil (L1). However, electricity likes to take the path of least resistance so when the electricity is allowed to flow from the collector to the emitter (~0 ohm resistance) it will stop flowing to the base because there is 47,000 ohms of resistance there. When the electricity stops flowing to the base, the base will open up the circuit again until the resistor offers less resistance than the Collector-Emitter path. This cycle repeats itself many times a second.

-   The primary coil collapses when the electricity stops flowing through it, when this happens, the secondary coil picks up the magnetic field and converts it back into voltage which gets stepped up to around a thousand volts in the process. The top load acts as a capacitor and increases the output from the secondary causing electrons in the air to become excited.

-   Finally, the oscillations from the secondary coil are fed back into the transistor in order to 'tune' or achieve maximum output from the Slayer Exciter.

For the music part, you can provide the output of an audio amplifier to the base of the transistor.

It’s showtime!:

This is the fun part. Sit back and watch some of the magic tricks with the slayer exciter ;)

1.This is the one i made last year

2. This is the video that inspired me to do it:

Can you make it too?

Definitely! But make sure you keep the following things in mind:

  1. You need a power transistor or a MOSFET for this purpose. Laboratory transistors can’t handle the current and the switching speed. I used the BT 136 for my circuit

  2. Make sure you get enamelled copper wires,and try to get it as cheap a possible,as it turns out to be the most expensive component.

  3. The secondary voltage will be very high,so be careful while demonstration.

You can look up to the following websites for step-by-step instructions:

- Pranav Udupa