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With this high-voltage generator according to the Tesla principle, you can create sparks of up to ten centimetres in length and you can 'play' a certain type of music via bluetooth. |
Getting to know the Tesla Coil 10
What can the Tesla Coil 10 do?
This device is a 'lightning generator' with which you can create sparks of up to ten centimetres in length. You can set both the repetition rate and the size of the output voltage with two potentiometers.
In addition, the Tesla Coil 10 has a Bluetooth receiver and an audio modulator on board. This allows you to modulate the output voltage with an audio signal. In this mode, you can 'play' music. The device then works as a plasma speaker. The sound is created by the pressure differences generated by the sparks in the heating air. However, normal MP3s do not sound good at all. You must use music specially composed for Tesla generators, so-called 'square music' files.
Manufacturer, suppliers and price
The device, together with a 48 Vdc power supply capable of delivering 2 A, is offered for prices between € 55.00 and over 100 euros. A thorough google search pays off! As with many Chinese products, the manufacturer is not mentioned. After some searching, we assume that this Tesla generator is manufactured by Wuhan Stark Technology Co. Ltd. from Wuhan City, China. The device is offered under various brand names, including Topacc, Joytech, Pemenol, Douk Audio, Ansecor, YBEST and Geeetech. The cheapest offer we could find was sold under the Geeetech brand name at AliExpress and at Banggood for a price of € 55.20 (price level March 2022).
The delivery of the Tesla Coil 10
The lightning generator is delivered, together with four neon lamps with which you can experiment, in a nice black box. The box contains a very brief instruction manual.
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| The Tesla Coil 10 comes in a nice box. (© Amazon) |
The manual
After some searching, we found a more comprehensive manual on the Internet . We have copied it to our cloud on Google drive, where you can download the PDF file:
➡ Tesla_Coil_10_Manual
The delivery of the power supply
Our package included a JSG-4820 type power supply with an American mains plug and an adapter for a Dutch wall socket. This power supply can be connected to a mains voltage between 100 V and 240 V. The device, measuring 13.0 cm x 6.0 cm x 3.5 cm, supplies 48 Vdc with a maximum current of 2 A.
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| The 48 Vdc power supply. (© AliExpress) |
The Tesla Coil 10 in a glance
The appearance
The electronics are housed in a transparent plexiglas casing, creating an attractive look. This housing measures 10.5 cm by 10.5 cm by 5.5 cm and weighs 400 grams. The bottom is completely taken up by an aluminium heatsink. At the front, there are two potentiometers for adjusting the frequency (1 Hz - 5 Hz) and intensity of the sparks. Next to it is the slide switch for changing from 'audio' (left) to 'sparks' (right). On the back there is a standard power connector for plugging in the 48 Vdc supply voltage. A 5.5 cm long needle can be attached to the top. The sparks are created at the tip of this needle.
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| The appearance of the Tesla Coil 10. (© AliExpress) |
Where has the Tesla coil gone?
Tesla generators are characterised by the large coil that is present on the top of the device or the PCB. In the photo below, we have collected a few such devices. This coil is in fact a transformer whose primary coil consists of one or at most a few windings and the secondary contains thousands of windings. A short, large voltage pulse is applied across the primary, resulting in a pulse voltage of up to tens of thousands of volts in the secondary. The operation of the transformer is further improved by making use of the resonant frequency of the primary coil, which causes a voltage surge.
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| The typical appearance of Tesla generators. (© 2022 Jos Verstraten) |
With the Tesla Coil 10 you'll search in vain for this distinctive coil. The innovative thing about this device is that this coil is integrated into the circuit board that forms the top of the housing. This is a double-sided circuit board measuring 9.8 cm by 9.8 cm. One large circular track is etched on the bottom side. On the top side, a spiral is etched which is composed of hundreds of extremely thin tracks. We put this circuit board under the microscope, using a ruler calibrated in millimetres as a reference, see the picture below. The distance between two black lines equals 1 mm. The needle is of course connected to the inner winding of the coil.
The primary voltage
Over the primary winding of the 'transformer', a voltage pulse is created that is many times higher than the supply voltage, see the oscillogram below. That is a consequence of the fundamental operation of a Tesla transformer. Not just an AC voltage is supplied to the primary, but a signal with a frequency equal to the resonance frequency of the primary circuit. In this way, one can make use of the very high voltage that a resonant circuit can generate.
A closer look at the primary voltage
The enlargement of the burst shows that the signal is quite sinusoidal and has a frequency of about 2.85 MHz.
The electronics in the Tesla Coil 10
In the photo below, you can see the PCB that is the bottom of the housing. On the left in the bottom corner is the bluetooth antenna with next to it a bluetooth chip AC218P09, which is unknown to us. On this board, we further discover two NE555 timers, a LM393 dual voltage comparator, a XL7015E DC to DC buck converter and a HY1908 N-channel enhancement mode MOSFET.
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| The spiral 'winding' of the Tesla coil on top of the PCB. (© 2022 Jos Verstraten) |
The primary voltage
Over the primary winding of the 'transformer', a voltage pulse is created that is many times higher than the supply voltage, see the oscillogram below. That is a consequence of the fundamental operation of a Tesla transformer. Not just an AC voltage is supplied to the primary, but a signal with a frequency equal to the resonance frequency of the primary circuit. In this way, one can make use of the very high voltage that a resonant circuit can generate.
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| The signal burst across the primary winding. (© 2022 Jos Verstraten) |
A closer look at the primary voltage
The enlargement of the burst shows that the signal is quite sinusoidal and has a frequency of about 2.85 MHz.
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| A few periods of the burst in view. (© 2022 Jos Verstraten) |
The electronics in the Tesla Coil 10
In the photo below, you can see the PCB that is the bottom of the housing. On the left in the bottom corner is the bluetooth antenna with next to it a bluetooth chip AC218P09, which is unknown to us. On this board, we further discover two NE555 timers, a LM393 dual voltage comparator, a XL7015E DC to DC buck converter and a HY1908 N-channel enhancement mode MOSFET.
Below the two 1R0 power resistors are the 2 x 3 pads for the two power MOSFETs that are soldered to the bottom of the PCB and attached directly to the heatsink. The heatsink is the same size as the PCB and is fixed with four bolts in the corners of the PCB. On the top of the PCB you can see in the middle the three free pads on which three wires are soldered that go to the 'transformer' board.
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| The PCB of the Tesla Coil 10. (© 2022 Jos Verstraten) |
Playing with the Tesla Coil 10
A word of warning
Tesla generators generate very strong electromagnetic fields around the transformer. Large induced currents and thus voltages can be generated in nearby metal objects, such as wires, cables and electronic equipment. As a result, operating the generator in the vicinity of electronic equipment can lead to malfunctions and even failure of these devices.
Persons with pacemakers or other electronic implants should definitely stay away from an operating Tesla generator! Also, do not place your smartphone right next to an operating Tesla generator!
Playing with the lightning generator
On the sales pages, it is stated that you can draw sparks of up to ten centimetres with this device. We always take such reports with a grain of salt, but in this case the claim is not exaggerated. In the maximum position of the 'PWR' potentiometer, such impressive 'lightnings' indeed erupts from the tip of the needle, see the picture below.
Catching the sparks with your finger is not painful, it only produces a tingling sensation. Only if you hold your finger close to the tip of the needle, you feel some of the intense heat that must be present in the discharge. The air is heated so intensely that the pressure waves make quite a noise!
In this position of the slide switch, you can of course experiment with all kinds of gas-filled tubes, such as the neon lamps that come with the generator. Old fluorescent tubes and energy saving lamps are also ideal to amaze your friends with objects that light up without being connected to anything.
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| The maximum length of the sparks. (© AliExpress) |
Playing with the music generator
Set the slide switch to the right position. The bluetooth function will be turned on and you can immediately pair with your smartphone or your tablet. According to the manual, the device's devicename is 'XFW-M18'. In our model, however, the Tesla generator neatly announces itself with 'Tesla Coil 10'.
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| Connecting the Tesla Coil 10 to a tablet. (© 2022 Jos Verstraten) |
The properties of 'square music'
As already mentioned, not every MP3 file is suitable for playback on a Tesla generator. You have to find a special kind of music, which is called 'square music'. What such music looks like is shown in the oscillogram below. All nuances have been removed from the amplitude curve, nothing much remains but 'there is sound' and 'there is no sound'.
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Oscillogram of 'square music'. (© 2022 Jos Verstraten) |
Search for 'square music'
You can find such files on YouTube and on Spotify. We have collected about ten tunes and put them on our cloud in Google Drive as a ZIP file:
➡ Tesla_Coil_Music.ZIP
If you click on this link you will get the following window on your screen. You can download the ZIP file by clicking on the icon indicated by the red arrow.
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| Ten 'square music' files in one ZIP. (© 2022 Jos Verstraten) |
How does it sound?
To give you an idea of what the Tesla Coil 10 sounds like as a plasma speaker, we have embedded one of those MP3s on this page:
Tesla Coil 10
