Ok, now we are getting somewhere. It looks like I can use a AC motor start capacitor with at least 400 AC volts along with my automotive coil and get some really nice arcs. Is this right? Feed my PWM 12 volts----use a 400volt AC start capacitor---and an ignition coil----sparks.
@hscess I don't know what your PWM outputs so impossible to know. If the output is only 12V then it'll never work well due to the internal resistance of the coil. The sparks occur when there is a fast 400V transient in the coil input. The purpose of the capacitor is just to limit long term current if the waveform/voltage is not suitable. The other way is to operate it is a flyback mode, then the sparks form when large current is suddenly switched off giving a large inductive voltage spike.
@hscess There is a link to coil guide I wrote a while ago in my video 100kV.... I-coils are transformers with ~1:100 ratio. So you need to hit it with 400V to get to 40kV. There are two ways to do it. First is to actually use ~400V, the other is to make a current, say 10A to flow through it (limited by internal resistance, 24V with optimized waveform works) and at maximum, quickly switch it off. This will give a voltage pulse due to inductive kick reaching 400V at the in and 40kV at the out.
If understood you right. !2vdc input to the PWM and output is AC, or am I not looking at this right. I know that the PWM chopps the 12vdc to controll motor speeds. I have tried to use dc capacitors and failed. The only one I can make work is the condensor/capcaitor that cam from a points type distributor.
@hscess The makes around 230VAC 50 Hz (EU-model) from 12VDC. The waveform is "modified sine wave" which is a kind of square wave with peak amplitude of 325V, but duty cycle giving around 230V average. The capacitor needs to be able to handle at least the peak voltage. I don't exactly know what you mean by dc cap, you should never use a cap with polarity with AC. Electrolytics are "DC", most others are bipolar and usable. Cap needs to be right and the 12V supply needs to be able to give ~1A.
@hscess Hmm, only vdc I know refers to the max volts of DC. I used a 0.47uF 1000V or so polyester capacitor which naturally isn't unipolar and never should be unipolar in this application since the inverter gives out AC. The purpose of the capacitor is to limit the short circuit current and allow the inverter to keep operating. Wrong value might break the inverter. Not power limiting the supply might also break the inverter.
whats the "suitable capacitor in series with the coil"? like the values for that capacitor, and what does it do? Wouldn't it render the square waves into a steady voltage?
I recall using 1uF, but that depends on your inverter voltage and waveform. A cap in series acts as a high pass filter and limits continuous current allowing only pulses to pass at the edges of voltage waveform.
The point is that without the cap the inverter frequency is too low for the coil and it will appear as short part of the time.
A parallel cap would act as a lowpass filter and a diode would rectify it to steady voltage. However that is not the case here.
I wonder if this would solve my problem: I have a 555 timer to transistor to give me a 20v square wave, however in-between pulses, the voltage to the ignition coil does not reach 0, so the coil doesnt spark, it only changes voltages that you can feel. I temporarily fixed this with a reed relay, however now i am frequency limited... So my conclusion is that my 555 timer is "leaking" small voltages that still trigger the transistor when it should be off..
Would adding a capacitor in series with the coil change this?
Also, perhaps my schematic is wrong: does it matter if my transistor is on the (-) side of the coil, because now it is on the (+) side of the coil, but shematics i see show it on the (-) side.
I suggest you read the description of my video "Ignition coils can handle quite high power levels", especially the first link (which should work). You can maybe skip the first section.
Adding a cap in series won't work in a typical low voltage transistor configuration, it is essentially different from the inverter thing. Polarity doesn't matter if you get current flowing and switch it off fast enough.
Especially the 2N3055 has quite low current gain and is not good in most configurations.
Are you sure your transistor is switching enough current (here 10A) and that the switch off is shartp enough? Are you using mosfets? Because many bipolars have relatively modest current gain and can require as much as 0.5A of control current. Mosfet's on the other hand have near infinite current gain.
There is some more detailed discussion about these problems in my other ignition coil videos. Check them out if you haven't, I'll need to update some old links so be patient if they don't work.
I believe it would be more accurate to say that you had your biasing of the transistor wrong way because switching polarity doesn't affect the coil, but cool anyways. Yes, IGBTs are great, quite similar to mosfets in this application though. IGBTs really stand out with tesla coils due to their high current handling.
Hi, i'm actually a motor mechanic that is having problems with spark from coils 'blowing out' when motors are running high boost. My question is how much damage does this do to the coil and can i make it work in a car, as an ignition system? I would appreciate any ideas that you have to give me, as you obviously play around with this kind of thing fairly often and with good results, thanks.
If I understood correctly this "blowing out" is not dangerous to the coil as it just decreases the energy of individual sparks due to shorter coil "charge" times for individual sparks at high RPM.
In electronic system this can be solved by using constant pulse lengths (instead of RPM dependent). Higher operating voltage might be needed depending on the coil if 12V is not enough to "charge" the coil fast enough in high RPM case (electronically easy). Some electronics required for a real system.
With an inverter like this just a small one similar to this video is possible. For good results something better is required (see my other videos).
The difference is that a normal Jacobs ladder uses higher continuous AC current which forms a flame like plasma. This rig just gives individual pulses and has relatively low energy density.
Just connect the inverter to 12V and the 230V side (or whatever, must be square wave) through series capacitor to the ignition coil (maybe 0.5uF). This can break your inverter so be careful. I used current limited power supply (12V/2A) instead of battery.
Ok, now we are getting somewhere. It looks like I can use a AC motor start capacitor with at least 400 AC volts along with my automotive coil and get some really nice arcs. Is this right? Feed my PWM 12 volts----use a 400volt AC start capacitor---and an ignition coil----sparks.
hscess 7 months ago
@hscess I don't know what your PWM outputs so impossible to know. If the output is only 12V then it'll never work well due to the internal resistance of the coil. The sparks occur when there is a fast 400V transient in the coil input. The purpose of the capacitor is just to limit long term current if the waveform/voltage is not suitable. The other way is to operate it is a flyback mode, then the sparks form when large current is suddenly switched off giving a large inductive voltage spike.
decod31 7 months ago
@hscess There is a link to coil guide I wrote a while ago in my video 100kV.... I-coils are transformers with ~1:100 ratio. So you need to hit it with 400V to get to 40kV. There are two ways to do it. First is to actually use ~400V, the other is to make a current, say 10A to flow through it (limited by internal resistance, 24V with optimized waveform works) and at maximum, quickly switch it off. This will give a voltage pulse due to inductive kick reaching 400V at the in and 40kV at the out.
decod31 7 months ago
If understood you right. !2vdc input to the PWM and output is AC, or am I not looking at this right. I know that the PWM chopps the 12vdc to controll motor speeds. I have tried to use dc capacitors and failed. The only one I can make work is the condensor/capcaitor that cam from a points type distributor.
hscess 7 months ago
@hscess The makes around 230VAC 50 Hz (EU-model) from 12VDC. The waveform is "modified sine wave" which is a kind of square wave with peak amplitude of 325V, but duty cycle giving around 230V average. The capacitor needs to be able to handle at least the peak voltage. I don't exactly know what you mean by dc cap, you should never use a cap with polarity with AC. Electrolytics are "DC", most others are bipolar and usable. Cap needs to be right and the 12V supply needs to be able to give ~1A.
decod31 7 months ago
Did you use vdc capacitor ? If so what size?
hscess 7 months ago
@hscess Hmm, only vdc I know refers to the max volts of DC. I used a 0.47uF 1000V or so polyester capacitor which naturally isn't unipolar and never should be unipolar in this application since the inverter gives out AC. The purpose of the capacitor is to limit the short circuit current and allow the inverter to keep operating. Wrong value might break the inverter. Not power limiting the supply might also break the inverter.
decod31 7 months ago
Did you use vdc capicitor? If so what size?
hscess 7 months ago
hey how can i test a twin ignition coil for 13b rotary engine?? it has a lot of wire... help please..
eric018 1 year ago
whats the "suitable capacitor in series with the coil"? like the values for that capacitor, and what does it do? Wouldn't it render the square waves into a steady voltage?
andypandy687 2 years ago
I recall using 1uF, but that depends on your inverter voltage and waveform. A cap in series acts as a high pass filter and limits continuous current allowing only pulses to pass at the edges of voltage waveform.
The point is that without the cap the inverter frequency is too low for the coil and it will appear as short part of the time.
A parallel cap would act as a lowpass filter and a diode would rectify it to steady voltage. However that is not the case here.
decod31 2 years ago
I wonder if this would solve my problem: I have a 555 timer to transistor to give me a 20v square wave, however in-between pulses, the voltage to the ignition coil does not reach 0, so the coil doesnt spark, it only changes voltages that you can feel. I temporarily fixed this with a reed relay, however now i am frequency limited... So my conclusion is that my 555 timer is "leaking" small voltages that still trigger the transistor when it should be off..
andypandy687 2 years ago
cont:
Would adding a capacitor in series with the coil change this?
Also, perhaps my schematic is wrong: does it matter if my transistor is on the (-) side of the coil, because now it is on the (+) side of the coil, but shematics i see show it on the (-) side.
andypandy687 2 years ago
I suggest you read the description of my video "Ignition coils can handle quite high power levels", especially the first link (which should work). You can maybe skip the first section.
Adding a cap in series won't work in a typical low voltage transistor configuration, it is essentially different from the inverter thing. Polarity doesn't matter if you get current flowing and switch it off fast enough.
Especially the 2N3055 has quite low current gain and is not good in most configurations.
decod31 2 years ago
Are you sure your transistor is switching enough current (here 10A) and that the switch off is shartp enough? Are you using mosfets? Because many bipolars have relatively modest current gain and can require as much as 0.5A of control current. Mosfet's on the other hand have near infinite current gain.
There is some more detailed discussion about these problems in my other ignition coil videos. Check them out if you haven't, I'll need to update some old links so be patient if they don't work.
decod31 2 years ago
ya i got it working, the transistor was on the positive side of the coil, not the negitive...
Thanks for your comments anyways.
Now for a plasma speaker- a friend of mine reccomended i use IGBTs.. I'll let you know how it goes.
andypandy687 2 years ago
I believe it would be more accurate to say that you had your biasing of the transistor wrong way because switching polarity doesn't affect the coil, but cool anyways. Yes, IGBTs are great, quite similar to mosfets in this application though. IGBTs really stand out with tesla coils due to their high current handling.
decod31 2 years ago
Hi, i'm actually a motor mechanic that is having problems with spark from coils 'blowing out' when motors are running high boost. My question is how much damage does this do to the coil and can i make it work in a car, as an ignition system? I would appreciate any ideas that you have to give me, as you obviously play around with this kind of thing fairly often and with good results, thanks.
devo4g63 2 years ago
If I understood correctly this "blowing out" is not dangerous to the coil as it just decreases the energy of individual sparks due to shorter coil "charge" times for individual sparks at high RPM.
In electronic system this can be solved by using constant pulse lengths (instead of RPM dependent). Higher operating voltage might be needed depending on the coil if 12V is not enough to "charge" the coil fast enough in high RPM case (electronically easy). Some electronics required for a real system.
decod31 2 years ago
i made my own mechanical relay to drive coils not very high performance but it works
prototype9000 2 years ago
wouldn't that kill the relay easily?
260830107 2 years ago
the relay usually will last for a long time with a ballast resistor and a capacitor to protect the points
prototype9000 2 years ago
View my Video... Computer + 2N3055 + Coil....
0903390901 3 years ago
That is a lot simpler then the device i made lol. I'm going to have to try that. sounds like a nice hot spark to. check out my videos for a demo.
sp00nix 3 years ago
can you make a jacobs ladder with that
Spiderpig4545 4 years ago
With an inverter like this just a small one similar to this video is possible. For good results something better is required (see my other videos).
The difference is that a normal Jacobs ladder uses higher continuous AC current which forms a flame like plasma. This rig just gives individual pulses and has relatively low energy density.
decod31 4 years ago
Kewl,Tesla would be proud
cfootball10 4 years ago
what do i need to make mine do that. starting from a car battery
bradmann85 4 years ago
Just connect the inverter to 12V and the 230V side (or whatever, must be square wave) through series capacitor to the ignition coil (maybe 0.5uF). This can break your inverter so be careful. I used current limited power supply (12V/2A) instead of battery.
decod31 4 years ago
whats that cylindrical thing below?
xXxmidgexXx 5 years ago
That's car ignition coil used to create the high voltage.
decod31 5 years ago