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Messages - iraquois

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Solid State Tesla Coils (SSTC) / Re: High Voltage Half Bridge Drive

« on: June 22, 2020, 08:39:51 PM »

Quote from: davekni on June 21, 2020, 08:26:42 PM

An NTC is good to limit inrush current charging the electrolytic cap after the bridge rectifier. If removing the lamp, replace it with a fuse. (You could rely on just the breaker in the circuit feeding the outlet you plug into. But I'd suggest being a bit more cautious than that.)

Okay. I will try. If I won't blow myself up then I will share my experience

Solid State Tesla Coils (SSTC) / Re: High Voltage Half Bridge Drive

« on: June 21, 2020, 08:34:49 AM »

Quote from: davekni on June 19, 2020, 08:55:11 PM

1800V is a confused meter. It is not real. All my cheap meters get confused by arcs or even just high-frequency power signals such as your 50kHz.

Lamps make great fuse alternatives for testing line-powered electronics. I'd suggest finding a higher wattage lamp rather than removing it.

Thank you for the reply. Eventually I am going to need to remove the bulb from the circuit. Could you suggest or give an idea for me to test if it is safe using it without bulb? Replacing bulb with NTC is enoıgh? What kind of safety circuitary is needed for this type of circuit?

Solid State Tesla Coils (SSTC) / Re: High Voltage Half Bridge Drive

« on: June 19, 2020, 11:24:30 AM »

Quote from: Weston on June 19, 2020, 10:55:00 AM

If you flyback is producing sparks its probably working (congrats!). The lamp will limit the total power drawn from the AC line to whatever its power rating is, and at that point little power is being delivered to your circuit. Do you expect your circuit to draw significantly less power than the rating of the lamp?

Are you measuring the voltage with a digital volt meter? High voltage stuff generates a lot of electrical noise which can cause incorrect readings on volt meters. Your transistors would fail way before 1800V.

Thanks a lot for your answer. Actually I am going to remove lamp. I built this circuit before. It was also working with lamp safely but when I remove the lamp, and start the pwm like %5 duty, Something blowed up , and one transistor died which is rated 1000V

one input of primary cable burned.(I noticed later, it was very thin cable. I am not sure if it was the reason. Also now I seperated rectifier side from the main circuit) I don't want this to happen again it was scary

. Do you think using an NTC is enough?

I tried again. The time It goes ~1800V is when I put arc cables far from each other.

Solid State Tesla Coils (SSTC) / High Voltage Half Bridge Drive

« on: June 19, 2020, 07:43:37 AM »

I am working on a project to produce high voltage output. Since I supply this circuit directly from mains I have some problems. Here is my representative circuit:
https://imgur.com/t9LxmNl

I am controlling transistors from a PWM generator. Duty cycle is %25. I checked for dead time. It is safe. Now, here I used safety bulb in series with the main (220VAC). When I plug it in Lamp goes fully on after 1-2 second later it goes almost off (just a little bit blinking). I thought first light is because capacitors are charging. So my questions are;

1) After I start pwm generator, I can see arcs but bulb also goes almost fully on. Is this a sign of a failure or short in the circut ?

2) I am checking voltage across C3 after I start pwm. Depending on my distance adjustment on flyback's secondary cables to have arc, it shows up to 1800V. Is this normal isn't it too much ?

3)I will later add voltage feedback and current feedback. Other then these additions, what kind of improvements should I do?

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

« on: May 26, 2020, 05:12:42 PM »

Thank you I see

Quote from: davekni on May 26, 2020, 06:31:59 AM

Anyone else know this circuit's operational theory?

Yes, it would be nice if someone explain it

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

« on: May 26, 2020, 01:12:46 AM »

Quote from: davekni on May 25, 2020, 08:17:18 PM

For the example in your link, I expect it's exactly as the text says, a piece of copper foil glued to the case. I suspect the case is painted or anodized. The copper foil makes a capacitor to the case. If one of the HV outputs arcs to the case, capacitance to the foil transfers that signal to the electronics, triggering fault shutdown.

Many SSTC designs use a similar "antenna". For SSTCs, the antenna isn't for fault detection, but for oscillation feedback. The antenna is a tiny capacitor to the SSTC output. (The frequency and distance for SSTC antennas make them behave as tiny capacitors. The distance is much shorter than a quarter-wavelength, so electromagnetic radiation is insignificant. That's why I put "antenna" in quotes.)

Thank you a lot. Do you think this circuit work without the feedback loop. I will use a transformer winded around a old TV flyback core. So I don't have that much space. It seems to me they use this for SSTC. Am I right?

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

« on: May 25, 2020, 07:43:30 PM »

Quote from: davekni on May 24, 2020, 09:55:48 PM

Most of the complexity of the second circuit is ground-fault protection for the HV output. Looks like it shuts down if either end of the output arcs to ground (ie. through a person) or to the transformer case.

The 56-64 turns comment appears to be a range of values for the primary winding, perhaps for different models. The turns ratio secondary/primary will be much higher.

I understand. Thank you.

So last one question. I see in a lot of schematics that there is a expression like in the picture which is marked with red circle. It seems it is for feedback but I don't know where exactly it is connected to. Does anyone have any idea?
https://imgur.com/CkNZIRq

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

« on: May 24, 2020, 02:08:53 PM »

Thanks a lot for your answers. Second circuit is a little bit odd to me. Will it boost 120 VAC (170VDC) to 4KV with a turn rate of 56/75 ?

Transformer (Ferrite Core) / Working Principle Of Neon Transformer Circuit

« on: May 23, 2020, 02:09:26 PM »

Hi. I am new to this forum and I couldn't find where to post this message. Sorry if it is in the wrong place. My intention is to make and understand the working of a 4kV 10mA 40W neon transformer circuit. I know it can be done with a flyback transformer and some pwm modules like tl494 sg3525 uc3845 NE555 etc... But Does anyone know what is inside a modern neon transformer. Actually my buildings are always produce 4kV from a power supply which has 12-24V and 2-3 amps. But as you know neon sign transformers are powered from directly 220V AC mains. Are they buck 220V to lower levels and then boost again or are they directly boost it to 4-10kv. I will be appreciated for any idea to show me the way I should start with. Thank you for reading.

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Messages - iraquois

Solid State Tesla Coils (SSTC) / Re: High Voltage Half Bridge Drive

Solid State Tesla Coils (SSTC) / Re: High Voltage Half Bridge Drive

Solid State Tesla Coils (SSTC) / Re: High Voltage Half Bridge Drive

Solid State Tesla Coils (SSTC) / High Voltage Half Bridge Drive

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

Transformer (Ferrite Core) / Re: Working Principle Of Neon Transformer Circuit

Transformer (Ferrite Core) / Working Principle Of Neon Transformer Circuit

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