Transistor Ignition Modules

[SmokedCircuit64]

Hello to all and I hope I can get some assistance on the circuit I need..

Being upfront.. I know nothing about electronics.. I can build you a car from the ground up. So I should be able to learn the basics of this..

So the short of the story.. I need a Transistor Ignition Module/Circuit to power an electromagnet. I want to use a hall effect switch to trigger the circuit. I want to use an input voltage of not less then 12 volts DC (like as in a car battery) so the circuit components need to be able to accept the input voltage. input amps would be the same as in a regular car battery. Timing for the circuit to charge the electromagnet should be very short. No I haven't built the electromagnet coil yet because I haven't found the ignition circuit to power it yet.

I have been searching the net and came across this:
JEH - Transistor Ignition Module page

But it can only use 6 volts input and the guy hasn't answered my question on what I would have to do to make it 12 volt compatible. So I'm left to build one for my self..

That should be enough to get this started!

Thx,
Kev

 

[Diver300]

It would certainly be better to buy an ignition coil than to try to make one.

I also think that making an ignition control circuit would be quite difficult. The current in the coil has to be able to build up very quickly. It also has to be limited so that at low revs the current does not get too big.

There are three ways of limiting the current.

1)The simplest is just to have enough resistance in series, either separately or with a coil with significant resistance.

2)The transistor can be arranged to limit the current. It will get hot and needs a big heatsink, but the circuit will work better.

3)The transistor can be timed so that it only turns on at the right time, and the current will have built up to the correct value at the time when it needs to be cut off to make the spark. This probably need a microcontroller to make it work, but nothing will get hot.

I think that you should be able to find a 12 V ignition system. I would have thought that they were more common than 6 V systems.

 

[SmokedCircuit64]

Just asking but did you look at the link that I put in my starter thread? It isn't hard at all.. The guy that built it just couldn't or wouldn't answer my email question asking if it could be modified for 12 volts.. I'm not planning to use it in a car..

 

[ronv]

Both the transistors are good for the 12 volts, but there is no part number for the hall sensor. The led would need a larger resistor I would suspect. Not sure why it's 6 volt only.

 

[SmokedCircuit64]

I think Diver300 thought I may be using it in a car.. I know the same or similar circuit has worked on a lawn mower engine (3 to 4.5 HP).. but I'm working on something different but kinda similar. I just figured because I will be using a mechanical wheel for timing the best way to go would be a circuit like an ignition circuit. It wasn't my first choice as I posed the question about wanting to use a hall effect switch for a timing device but needed help locating one that could pass 12 volts.

Thanks for the reply ronv.. Could I still use the JEH circuit board and just change out some of the components ya think?

Thx,
Kevin

 

[ronv]

My guess is yes but it is impossible to say with certainty without a schematic.
If you want to share with us what you want to do I am sure someone can come up with a circuit that will work. It is not so complicated it couldn't be built on a vector board if your handy.

Maybe we can back it out from the picture.

 

[shortbus=]

Why not use a four pin GM HEI module? It's made for 12V, has the hall sensor built in and is sealed/water proof. All you need to worry about is the magnet to trigger it then.

 

[ronv]

TX Ign.

It's not a super good circuit, but yes you could change a couple of resistors and make it work on 12 volts. See attached schematic.

 

[SmokedCircuit64]

Why not use a four pin GM HEI module? It's made for 12V, has the hall sensor built in and is sealed/water proof. All you need to worry about is the magnet to trigger it then.

I might have a GM HEI distributor around here somewhere, I will have to check.. So do I just need the module out of it right?

 

[SmokedCircuit64]

It's not a super good circuit, but yes you could change a couple of resistors and make it work on 12 volts. See attached schematic.

ronv,
Thanks for the circuit design.. But I have to admit that I am TOTALLY dumb when it comes to reading those things. Wire diagrams I can follow because they are a little more traceable as in you can see what comes from what point and leads to the next point and follow the flow of current.. I know you spent a good bit of time working it out for me. Is there a way you could make a components/parts list for me?

I think I should also get a bread board circuit testes kit like from radio shack or off ebay.. Maybe then I can understand the flow of things.

You mentioned that it is not a super good circuit.. is there some sort falls I need to pay attention to?

 

[SmokedCircuit64]

My guess is yes but it is impossible to say with certainty without a schematic.
If you want to share with us what you want to do I am sure someone can come up with a circuit that will work. It is not so complicated it couldn't be built on a vector board if your handy.

Maybe we can back it out from the picture.

So let me explain the project.. No it is not for a class I'm taking, more it is derived form a question my son asked me and then he asked if we could build it.. Ooo A challenge!!

What we have is a old electric compressor pump housing with a simple piston a piston rod and flywheel. We removed the burnt electric motor.

My son asked if there was a way to make the assembly move (not function as a compressor) just move.. I looked it over and suggested maybe we could do something with the repulsive force of some N42 magnets. We fastened one magnet to the top of the piston and held a second magnet so that the like poles of the magnets were facing each other. Yes we were able to make it move, almost through a complete cycle! But the magnets repel all the time which means on the up stroke of the piston the repulsive force slows the momentum and stalls it out.

The only way to go is by using something that can be switched on and off like an electromagnet. Then it would need to be timed to do that at a specific point in the motion of the piston. Unlike a ICE which fires just prior to TDC ours would be fired just after TDC where gravity would help push it through a cycle.. Then we would fire up an electromagnet set to repel the magnet fixed to the top of the piston..

I am loving the challenges we are dealing with and seeing my son work through the issues like figuring out what size magnets we can use and all the “if we did this, then we have to worry about that” type of things.. Besides, it seems like a good father and son learning and bonding experience.

My choice of using 12 volts comes from the fact I have a 120 VAC to 12 VDC converter, which means we can toy around with it all we want and don't have to worry about recharging batteries or fumbling with a bunch of little batteries.

There is my project in a nut shell. Hope I didn't put you to sleep.

 

[KeepItSimpleStupid]

You should check out this article: Computer Controlled Air/Steam Engine - Nuts and Volts There were some questions/errors posed in the next issue in the letters to the editor.

 

[ronv]

Magnetic Engine

Sounds like fun!
Here are some problems I see with that circuit:
I'm not sure how big your compressor is but I can see where you might need quite a bit of current in the electromagnet. The circuit is good for 2 or 3 amps maybe a bit more because it won't always be on (unless the magnets come to a stop under the sensor).
The biggest problem I see is that the hall only turns it on when the little hall magnet is under the sensor. I suspect you need it to be on for an inch or two. I'm guessing you will put the magnet for the hall on the fly wheel? Some kind of strip magnet might work or perhaps a reflective sensor. If your goal was to use the board and most of the parts from the kit I think we can make that work or I'll look around for something similar.
Sorry I am kind of thinking out loud.

 

[SmokedCircuit64]

Ronv,

The compressor piston only has a diameter is 1.74", so not all that large. we are using a 1.5"X.125" N42 magnet fastened to the top of the piston because the piston total height is .250" (1/4). Unlike a ICE piston which moves straight up and down in the cylinder, the compressor piston actually tilts from side to side as it moves through a up/down cycle.
I guess at some other point back in 2006 some one started the same thread here but it died out, but one reply mentioned the use of an optical switch verses a hall effect switch. But that is where the thread stopped with no info on using one over the other. My thought was to get something working then entertain changes.

Yes I did plan to mount some magnets on the flywheel to switch the hall effect switch. I don't see this running very fast so I may be able to use the magnet tape on the flywheel. Do you think the reflective sensor would be a better choice being the flywheel is steel and that my effect the timing of the hall using magnets? I have a roll of reflective aluminum tape I could use. Paint the rim of the flywheel a flat black and the locate the start/finish points for the reflective tape. As for the flywheel stopping in the exact spot where the magnets aline with the hall and leaving a open circuit situation, I would think that if we can get this working we could alter the circuit with something timed that would shut the circuit off after a few seconds.. But that is secondary in the scheme of things i would think.

Now because I am not 100% sure how the electromagnet coil would actually work I ordered a 12 volt electromagnet coil that can hold/lift 40kg (88.2 lbs) and it had a diameter of 49mm (1.93 inches) just a little larger than the opening in the housing for the cylinder but smaller than the bolt circle that holds the cylinder sleeve in place.

I thank you for all your assistance. Once I get enough of the components together I'll post some pictures so you can reap some satisfaction from this as well. Let me clean up my work space and I'll lay out the basic building blocks we are starting with and post pictures of that as well..

Hey this is a work in progress, think out loud all you want..

Thanks,
Kev

 

[SmokedCircuit64]

ronv,

I'm actually thinking that going with the optical switch may be the best bet for what we are working on. I say that because we may have some problems with the magnets and the steel flywheel and trying to dial in the timing for the hall switch. Sorry if that complicates the circuit your helping me with.

 

[SmokedCircuit64]

You should check out this article: Computer Controlled Air/Steam Engine - Nuts and Volts There were some questions/errors posed in the next issue in the letters to the editor.

I tried to download the file from the site link you gave me but I don't have internet explore on my computer to open it up.. Thanks though!

 

[ronv]

Actually I think the optical sensor would be the best. Do you have a link to the coil? That would tell us how much current is needed to drive it. I think we can come up with a very simple circuit to drive it in one direction. More complicated to make it push and pull.

 

[SmokedCircuit64]

I can't find a site for the electromagnet coil as I got it off eBay. I did alot of searching for one the size I needed and it was the closest one I could find. I also took a quick look on eBay for the optical sensor to get an idea and maybe some part numbers. They had a few that I would spring for. I might even be able to pick something up at the local radio shack.. I will have to look this week.

Unless there is some place to refurbish one from like a hold hard drive or something.. I have a few of those around here.

 

[ronv]

Mag Driver

Here is a schematic of the circuit. You can get the parts at mouser.com. Let me know if you would like a pictorial of how to hook the parts together.

 

[SmokedCircuit64]

Thanks for the schematic of the circuit.. If it isn't too much trouble, then yes I'd like a pictorial of how to hook the parts together.
One question.. Is this circuit you made for me based off the circuit board and parts used by the JEH circuit board or do I need to make a new board and get all new parts?

I took pictures after I cleaned up my little work area a little.. I post them in just a few minuets.