1 stage CG, thyristor, I need repeated fire? (circuit help)
PlayNice, Wed Apr 10 2013, 09:26PMI would like to make a 1 stage repeat fire CG. I would like to use 2 thyristor and non-polar caps so that energy just goes back an forth from one side of the cap to the other.
So say:
1st shot some of the Cap energy is used but the rest goes to the opposite side of the cap through thyristor #1
2nd shot energy goes the other way back into the other side of the cap through thyristor #2
3rd shot energy goes the other way again through #1 thyristor same as shot 1
4th shot is same as 2nd... and so on
each shot draining some of the total energy for my caps. Yenderson drew this for me once but its for a 2 stage, is there any way to add 2 thyristors to one coil so that 1st thyristor controls energy one way, and the 2nd thyristor controls energy the other way?
PS. this is not going to be a powerful CG, just want a small scale experiment to see the results
Wait, would just one thyristor work here? Connect caps, 1 thyristor in series, and 1 coil in series? Everytime the thyristor receives a signal from the opto switch it will fire in the reverse direction??
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Ash Small, Thu Apr 11 2013, 12:30AM
One capacitor, one thyristor, one coil, and a double pole, double throw switch should do it, but you'd need to flick the switch between each shot. (could also be done with an H-bridge, and driver circuit if you want it fast and automated) (not a 'conventional' H-bridge, but one where the two high side transistors are connected together, and the two low side transistors are connected together, with the coil connected between the two high side emitter/sources and the two low side collector/drains, with one source/emitter and one drain/collector connected to each terminal of the capacitor.)
I can draw a sketch if required, (now I think about it you won't need the thyristor, just four transistors.....then again, I think you could use four thyristors)
I think this should work if you fire each diagonal pair together, like a conventional transistor H-bridge.
Ash Small, Thu Apr 11 2013, 12:30AM
One capacitor, one thyristor, one coil, and a double pole, double throw switch should do it, but you'd need to flick the switch between each shot. (could also be done with an H-bridge, and driver circuit if you want it fast and automated) (not a 'conventional' H-bridge, but one where the two high side transistors are connected together, and the two low side transistors are connected together, with the coil connected between the two high side emitter/sources and the two low side collector/drains, with one source/emitter and one drain/collector connected to each terminal of the capacitor.)
I can draw a sketch if required, (now I think about it you won't need the thyristor, just four transistors.....then again, I think you could use four thyristors)
I think this should work if you fire each diagonal pair together, like a conventional transistor H-bridge.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
PlayNice, Thu Apr 11 2013, 02:00AM
Thanks for the info and the sketch.
This would require 2 different input triggers right? I was hoping to just use one trigger from my opto switch. Any way to achiave this with one input? Or is there any SIMPLE device that can change my opto switch output into 2 oscilating signals.
And yes I would rather have this be fast and automated so the DPDT switch idea wont work.
PlayNice, Thu Apr 11 2013, 02:00AM
Thanks for the info and the sketch.
This would require 2 different input triggers right? I was hoping to just use one trigger from my opto switch. Any way to achiave this with one input? Or is there any SIMPLE device that can change my opto switch output into 2 oscilating signals.
And yes I would rather have this be fast and automated so the DPDT switch idea wont work.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Ash Small, Thu Apr 11 2013, 10:29AM
I think something like a TL494 (or similar chip used for driving H-bridges) could be used to provide the alternating trigger pulses.
I imagine you could use any of the basic H-bridge driver circuits, but modified for this application.
I think you'd need some form of isolation for the high side thyristor drivers, Yanderson knows a lot more about driving thyristors than I do.
Ash Small, Thu Apr 11 2013, 10:29AM
I think something like a TL494 (or similar chip used for driving H-bridges) could be used to provide the alternating trigger pulses.
I imagine you could use any of the basic H-bridge driver circuits, but modified for this application.
I think you'd need some form of isolation for the high side thyristor drivers, Yanderson knows a lot more about driving thyristors than I do.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Yandersen, Fri Apr 12 2013, 06:31PM
Qx6, don't be too excited about oscillating circuit for multifiring. In best case you will have half energy for the second shot. If both bullets are the same, shot parameters will be way too different.
If you will put enough energy into single stage, you will recuperate insignificant amount of energy for the second shot.
Forget this stupid idea. Use it as double stage. Unless it is the problem for you to wind two coils...
Yandersen, Fri Apr 12 2013, 06:31PM
Qx6, don't be too excited about oscillating circuit for multifiring. In best case you will have half energy for the second shot. If both bullets are the same, shot parameters will be way too different.
If you will put enough energy into single stage, you will recuperate insignificant amount of energy for the second shot.
Forget this stupid idea. Use it as double stage. Unless it is the problem for you to wind two coils...
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Ash Small, Sat Apr 13 2013, 01:06AM
I agree it doesn't seem to make a lot of sense, but we don't know the reasons behind this project yet.
Ash Small, Sat Apr 13 2013, 01:06AM
Yandersen wrote ...
Qx6, don't be too excited about oscillating circuit for multifiring. In best case you will have half energy for the second shot. If both bullets are the same, shot parameters will be way too different.
If you will put enough energy into single stage, you will recuperate insignificant amount of energy for the second shot.
Surely this depends on how much energy is stored in the capacitor to start with? I agree that the energy left after each shot will be less, but if sufficient energy is stored to start with, and if resistive losses are low, then a significant amount of energy will be left.Qx6, don't be too excited about oscillating circuit for multifiring. In best case you will have half energy for the second shot. If both bullets are the same, shot parameters will be way too different.
If you will put enough energy into single stage, you will recuperate insignificant amount of energy for the second shot.
I agree it doesn't seem to make a lot of sense, but we don't know the reasons behind this project yet.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Yandersen, Sat Apr 13 2013, 07:57AM
I have some exp. Practical one. So just believe me.
Yandersen, Sat Apr 13 2013, 07:57AM
I have some exp. Practical one. So just believe me.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
PlayNice, Sat Oct 05 2013, 08:01AM
God sorry guys I forgot I started this.
I have a weird new design for a coilgun that I would like to test out so one coil is all I can do. Space and design is the problem.
Yend, are you saying no matter how big and how much energy is in my caps after the first shot I will only have 50% or less energy? If that's the case yea there is no point in this design. I was thinking like AshSmalls that if the caps are huge I would have much more then 50% energy left after first shot
Let me know what you think please
PlayNice, Sat Oct 05 2013, 08:01AM
God sorry guys I forgot I started this.
I have a weird new design for a coilgun that I would like to test out so one coil is all I can do. Space and design is the problem.
Yend, are you saying no matter how big and how much energy is in my caps after the first shot I will only have 50% or less energy? If that's the case yea there is no point in this design. I was thinking like AshSmalls that if the caps are huge I would have much more then 50% energy left after first shot
Let me know what you think please
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Yandersen, Mon Oct 07 2013, 04:40AM
The bigger the coil the more energy you will recuperate. The smaller the capacitance the more energy you will recuperate. The shorter the pulse, the more energy you will recuperate.
Simply divide your coil onto two halves to get two coils.
But I doubt you will ever do anything in your life. Still... If miracle will happen, keep repolarized cap away from the charger otherwise it will blow.
Yandersen, Mon Oct 07 2013, 04:40AM
The bigger the coil the more energy you will recuperate. The smaller the capacitance the more energy you will recuperate. The shorter the pulse, the more energy you will recuperate.
Simply divide your coil onto two halves to get two coils.
But I doubt you will ever do anything in your life. Still... If miracle will happen, keep repolarized cap away from the charger otherwise it will blow.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
PlayNice, Tue Oct 08 2013, 03:51AM
No offense Yand, but with that kinda of reply I very much doubt anyone even listens to what you have to say lol
PlayNice, Tue Oct 08 2013, 03:51AM
No offense Yand, but with that kinda of reply I very much doubt anyone even listens to what you have to say lol
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Steve Conner, Tue Oct 08 2013, 01:28PM
Zzzwhat... Quit squabbling, young whipper-snappers.
If you want to do energy recovery, the best circuit I know of is the diagonal half-bridge with two IGBTs and two diodes.
You can use as big a capacitor as you like because you can end the pulse before it discharges completely, by turning the IGBTs off. This means you could use a huge capacitor and store enough energy for several shots. It can be polarised because the voltage never reverses.
The unused magnetic energy in the coil gets returned to the capacitor via the diodes, so you can use it for the next shot.
Steve Conner, Tue Oct 08 2013, 01:28PM
Zzzwhat... Quit squabbling, young whipper-snappers.
If you want to do energy recovery, the best circuit I know of is the diagonal half-bridge with two IGBTs and two diodes.
You can use as big a capacitor as you like because you can end the pulse before it discharges completely, by turning the IGBTs off. This means you could use a huge capacitor and store enough energy for several shots. It can be polarised because the voltage never reverses.
The unused magnetic energy in the coil gets returned to the capacitor via the diodes, so you can use it for the next shot.
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
PlayNice, Wed Oct 09 2013, 07:41AM
Ok that really sounds good as I already have all the parts to build it. Steve are you talking about something like this then?:
PlayNice, Wed Oct 09 2013, 07:41AM
Ok that really sounds good as I already have all the parts to build it. Steve are you talking about something like this then?:
Re: 1 stage CG, thyristor, I need repeated fire? (circuit help)
Steve Conner, Wed Oct 09 2013, 09:18AM
Yep. The only difficulty is that you need floating gate drive for M1.
Steve Conner, Wed Oct 09 2013, 09:18AM
Yep. The only difficulty is that you need floating gate drive for M1.
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