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Every inexpensive energy-saving lamp contains a self-resonant voltage inverter designed for low-power operation, typically up to a few watts. It raises the question of why not scale up this concept and replace the resonance circuit used to generate the necessary lamp voltage with the tuned primary of a double-resonant solid-state Tesla coil (DRSSTC). The community at teslacoil.net has already explored this, and devices like the SSTC3, SSTC3.7, SSTC3.8, and SSTC3.9 are based on such circuits. Experiments have shown that this idea can produce impressive electrical discharges with a straightforward and reliable circuit. Besides the simple self-resonant power stage, a suitable power supply with current-limiting features is essential. Further exploration could address significant drawbacks associated with DRSSTCs, such as sound intensity and relatively thin discharges at low power levels. The discharges from an interrupted solid-state Tesla coil (ISSTC) are generally more pleasing to the ear compared to the loud noise produced by a DRSSTC operating at high burst rates. This is attributed to the longer pulse duration with a sinusoidal waveform derived from the mains used in ISSTCs. There was some online discussion regarding DRSSTCs with long pulse times a few years ago, but the specific details remain elusive. Given the absence of publicly available circuits resembling the proposed design, efforts are underway to develop a simple, self-resonant DRSSTC featuring prolonged on times and a sinusoidal pulse envelope. Since the waveform of a self-oscillating Tesla coil cannot be controlled within the power stage, this control must be managed elsewhere, specifically in the power supply. The circuit includes components such as TR2, diodes D10-D13, and the circuitry around IC7 and IC8, which form the low voltage power supply for the control logic. A five-volt regulator (IC8) is included for future voltage requirements. The toroidal inductor L1 features a half-turn primary that carries the primary resonance current. The output current from L1 causes a voltage drop across R26, which is rectified by diodes D15-D18, with C9 smoothing the resulting signal. A comparator (IC3) generates a logic high signal at its output when the current threshold is exceeded, and this threshold can be adjusted using R23. For zero-cross detection, the secondary voltage from the mains transformer is fed through either D9 or D21 and R10 into the base of transistor T3, with the choice of diode determining the phase. The delay time between pulses is created by the circuit around IC1B and synchronized with IC2A and IC1A. The over-current shutdown release is also synchronized using IC2B, with the over-current shutdown capable of being triggered at any time, forcing the output low through T7. This transistor is connected in a wired-OR configuration with T6 to generate the power switch signal, which remains high for one half-wave period of the mains voltage, activating a MOSFET in the power stage supply line until an over-current condition arises. The remaining circuit, including T4, T5, IC1C, and IC1D, generates a pulse burst to trigger an SCR that switches power to the power stage. This configuration is utilized when operating the circuit without over-current protection, as SCRs have proven to be more robust than MOSFETs. The schematic of the power stage is depicted in figure 1.2. The IGBTs T1 and T2 form a half-bridge circuit, protected by diodes D1-D6 against voltage transients and reverse current flow. Resistors R1 and R2 dampen oscillations on the gates of T1 and T2. Toroidal inductors L2 and L3 are employed for feedback, with a small portion of the output power coupled back through two turns of both feedback coils and the current measurement coil, as illustrated in figure 1.3.

The proposed circuit architecture leverages the advantages of a DRSSTC while addressing its limitations. The self-resonant design allows for efficient energy conversion, while the incorporation of a sinusoidal pulse envelope enhances the quality of the output discharges. The use of a current-limiting power supply ensures safe operation, preventing damage during over-current conditions. The feedback mechanism implemented through the toroidal inductors provides a means for real-time adjustments to the output characteristics, optimizing performance under varying operational conditions. The careful selection of components, including the robust SCRs and IGBTs, enhances the reliability and durability of the system, making it suitable for various applications in high-voltage experiments and demonstrations. Overall, this design represents a significant advancement in Tesla coil technology, merging simplicity with effectiveness while pushing the boundaries of traditional designs.Every cheap energy-saving lamp has a self-resonant voltage inverter inside. They are designed for low-power operation up to a few watts. Why don`t scale up the whole thing and replace the resonance circuit for generating the needed lamp voltage with the tuned primary of a double-resonant solid state tesla coil (DRSSTC) T he guys from teslacoil. net did this already and I think that the SSTC3, SSTC3. 7, SSTC3. 8 and SSTC3. 9 as well as some of the other coils are based on such a circuit. My experiments showed that the idea is good and you can create amazing lightning with a very simple and reliable circuit. The only thing you need - apart from the simple self-resonant power stage - is a suitable power supply with a current-limiting feature.

But why stop thinking here We could even try to avoid other major disadvantages that a DRSSTC has: Sound intensity and relatively thin discharges, especially at low-power. The discharges from a interrupted solid-state tesla coil (ISSTC) are more pleasant to the ear than the screaming noise of a DRSSTC at high BPS and somewhat brighter.

This is because of the long pulse time with a sinusoidal waveform (that is derived from the mains) used in a ISSTC. Regarding DRSSTCs with long pulse times, there was some discussion on the web a few years ago, but I could not figure out where this was.

However, as I think that there are currently no circuits like the sketched one in the public domain, I decided to spend some time on developing such a circuit: A simple, self-resonant DRSSTC with long on time and sinusoidal pulse envelope. As the waveform of a self-oscillating tesla coil can`t be controlled in the power stage, this control has to be done elsewhere.

The power supply was chosen to be the right place for this (see Figure 1. 1). TR2, D10 - D13 and the circuit around IC7 and IC8 are the low voltage power supply for the control logic. The five volt regulator (IC8) is a spare part for future use, where the voltage may be needed. The toroidal inductor L1 has a half-turn primary that carries the primary resonance current. The output current from L1 leads to a voltage drop at R26, which is rectified by D15 - D18. C9 smoothes the signal. The following comparator (IC3) generate a logic high signal on it`s output if the current threshold is exceeded.

The current threshold can be set using R23. For the zero-cross detection, the secondary voltage from the mains transformer is fed via D9 or D21 and R10 into the base of T3. The placement of D9 or D21 can be used to select the right phase, only place one of the diodes at a time.

The delay time between the pulses is generated by the circuit around IC1B and synchronized with IC2A and IC1A. The over-current shutdown release is synchronized too, using IC2B. The over-current shutdown can be triggered at any time and force the output low using T7. This transistor is connected in a wired-or configuration with T6 to generate the power switch signal.

This signal is high for the duration of one halfwave period of the mains voltage and switches a MOSFET in the power stage supply line on, until an over-current condition occurs. The rest of the circuit, consisting of T4, T5, IC1C and IC1D, generates a pulse burst for triggering a SCR that switches the power to the power stage.

This option has been used when running the circuit without over-current protection, as SCRs have been found to be more robust than the MOSFET switch. The schematic of the power stage is shown in figure 1. 2. The IGBTs T1 and T2 form a half-bridge circuit. They are protected by D1 - D6 against voltage transients and reverse current flow. R1 and R2 damp the oscillations on the gates of T1 and T2. L2 and L3 are toroidal inductors and are used for the feedback. A small amount of the output power is coupled back by the two turns through both feedback coils (and the current measure coil, see figure 1.

3). D1 and D2 are s 🔗 External reference