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I’ve designed an SSTC circuit which is based on a different topology and I wanted to accomplish it in real life. The circuit is operating at approximately 1.5 MHz during resonance and inherently, the circuit works as if it is interrupted. The schematic is given below:

Hand-drawn schematic

In order to see whether the expected results occur and get the required voltage, current and power ratings of the circuit components for the sake of a safe operation, I’ve also simulated the circuit on Multisim with a slightly different arrangement without interfering with the main working principle. The simulation circuit is given below:

The simulation circuit

Additionally, I’ve captured the primary winding voltage waveform which was complying with the theoretical calculations. The waveform is as follows:

The primary coil voltage waveform

After those set of processes, I’ve gathered the components and created the circuit. By the way, I haven’t included a topload on the secondary coil.

Before turning on the DPDT switches (those are shown with SPST switches in the first diagram), I’ve known that the base terminal connection of the secondary coil must be taken into a bit special consideration as the presence of a high-in-amplitude and RF signal that is generated on the secondary winding. I’ve searched possible solutions on the internet and I’ve found a solution that is about attaching a conductor material to the base terminal. I’ve cut a 30 cm x 30 cm aluminium foil and soldered the base terminal on it. However, I wasn’t sure whether that solution would work fine.

I’ve turned on both switches, and consequently, I haven’t seen the main action to which I'd been looking forward (i.e. the corona discharge) even though I’ve hit the top terminal of the secondary coil with a metal and approached a light bulb to it. Apart from that result, both circuits (the linear power supply and switching circuit) have worked properly.

I don’t have any idea whether I can connect the base terminal to the mains ground and as to the possible dangerous results of connecting the base terminal to the mains ground. Apparently, despite some users have chosen this way, it is ill-advised. I am not able to directly ground the base terminal as I am living in the top flat of a 4-floor apartment.

What is going wrong with my circuit?

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  • \$\begingroup\$ Your resistor values on the bases of 2N2222 transistors seem too high. TIP3055 has no biasing (on its base). The pulse width on your signal seems too wide (nearly 1ms), the voltage too low, as if barely anything is passing through, which is no surprise considering my points above. Your L1 has no path to the other side of it when one TIP3055 transistor is on, except by having the C2 charged when Q3 is on, and then discharged through the L1 when Q4 is on, but there is no parallel 2-way connection between the C2 and L1 to make it oscillate except for the moment when Q4 is on. \$\endgroup\$ Sep 27, 2021 at 11:13
  • \$\begingroup\$ This is a highly questionable schematic, and it makes me wonder where did you find it, and why did you go with it when there are simpler, working schematics of a Tesla coil available on the Internet? \$\endgroup\$ Sep 27, 2021 at 11:15
  • \$\begingroup\$ @EdinFifić The circuit is my own design. Although there are numerous topologies (It is not the first time that I am making an SSTC circuit, the one that I'd done in the past has worked correctly.), I've planned to design a different circuit that resembles the spark gap Tesla coil LC tank circuit with transistors in the place of the spark gap. The main reason for seeking that approach of mine was to overcome the problems that are introduced by the high frequency operation i.e. the oscillation is done by the LC circuit rather than pushing transistors to the edge. Thank you for your advice. \$\endgroup\$ Sep 27, 2021 at 13:09

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