Spark-Gap Tesla Transformer

Posted on Jul 31, 2015

I built two secondary coils: Small coil D25.4/H119 (Diameter=25.4mm and Height=119mm) and Medium coil D73/H228. I experimented with the spark gap, and observed that a series spark gap is better in terms of power handling, noise, and spark discharge length. The capacitance is very important. It should be able to pump a high current, so a low ESR and a low inductance pulse type capacitor is required.

Spark-Gap Tesla Transformer
Click here to download the full size of the above Circuit.

I tested this coil with two different primary caps. First I constructed a water filled jar cap using aluminum foil as shown in Fig. 3, and measured its capacitance as 352pF. The estimated voltage rating was about 20KV. I run a 
bunch of tests by varying the supply voltage, changing the spark gap configuration, and putting different discharge terminals. A series spark-gap configuration involving four or more gaps gives the best performance.

However, the total gap spacing must not be larger than 5-6mm to protect the primary capacitor. A series arrangement is quieter. The streamers emanating from the discharge terminal are quite visible in the dark. And I measured a spark discharge of about 3-3.5cm using a grounded rod. The estimated voltage output was about 70KV. The coil and the streamers are shown in Fig. 2 and 3, respectively.  

Then I tested the same secondary using a 2.53nF/16KV MMKP array as shown. Primary inductor was replaced too. Since the cap has been increased, a much lower primary inductance was needed. The spark length was about 4.5-5 cm. However, the spark gap firing rate has been reduced. A higher current is needed from the HV transformer.. By  4beowulf7 -

PCB file: Click here to download 255 file.PCB file: Click here to download 255 file.

Leave Comment

characters left:

New Circuits



Popular Circuits

Lithium charger circuit
Thermally Operated Direction Detector
Cw Keyer
Sawtooth Generator For Sweep Generators
20A Transformerless Power Supply Schematic Diagram
Vehicle Sensor Control for Parking Lot Management System
Schematic MP3 Car Audio Power AmplifierCircuits
Bistable Multivibrators
Open water notification Circuit Design