Driving high amp device.
JW Smythe
Posts: 12
Hello all.
I'm new to the basic stamp stuff, but am enjoying so far. I'm a programmer, but not a great electronics guy, so I'm stumbling around in the dark a lot.
I need some advice on how to run a high amp DC device at a fairly high frequency.
I'm trying to make an automotive ignition coil spark (think Jacob's ladder).
The coil I'm using is suppose to put out 45kV with a 12V input, and should draw roughly 8A. I need to pulse the input to make it spark, which is why i'm using a basic stamp (HomeWork Board).
Several people had suggested to me to build a 555 timer circuit. I've made them work, but eventually end up burning out something, usually the 555 chip, while just testing with small loads, even though I am using a 2N3055 transistor.
I'm very pleased with the level of control I have with the basic stamp.
I'm not quite sure how to isolate the coil, without risking burning out the basic stamp. I don't feel save using the transistor. I can already smell the smoke. [noparse]:)[/noparse]
I found some mention of solid state relays. I have absolutely no experience there. What exactly should I be shopping for? Is there a better option? I'm open to suggestions, rather than just burning up a perfectly good board. Whatever I use needs to be able to handle a decent frequency. The coil can handle over 850Hz, and I'd like to try it all the way up there.
Post Edited (JW Smythe) : 10/14/2006 9:04:52 PM GMT
I'm new to the basic stamp stuff, but am enjoying so far. I'm a programmer, but not a great electronics guy, so I'm stumbling around in the dark a lot.
I need some advice on how to run a high amp DC device at a fairly high frequency.
I'm trying to make an automotive ignition coil spark (think Jacob's ladder).
The coil I'm using is suppose to put out 45kV with a 12V input, and should draw roughly 8A. I need to pulse the input to make it spark, which is why i'm using a basic stamp (HomeWork Board).
Several people had suggested to me to build a 555 timer circuit. I've made them work, but eventually end up burning out something, usually the 555 chip, while just testing with small loads, even though I am using a 2N3055 transistor.
I'm very pleased with the level of control I have with the basic stamp.
I'm not quite sure how to isolate the coil, without risking burning out the basic stamp. I don't feel save using the transistor. I can already smell the smoke. [noparse]:)[/noparse]
I found some mention of solid state relays. I have absolutely no experience there. What exactly should I be shopping for? Is there a better option? I'm open to suggestions, rather than just burning up a perfectly good board. Whatever I use needs to be able to handle a decent frequency. The coil can handle over 850Hz, and I'd like to try it all the way up there.
Post Edited (JW Smythe) : 10/14/2006 9:04:52 PM GMT
Comments
I have played with·a lot of high voltage stuff, but have never actually interfaced a Stamp with HV.
What are you trying to do with the ignition coil, exactly? Do you want a plasma source, to just make some sparks, power a marx gen, what? I ask because it will be much easier to help if we know. Does the drive frequency need to vary? If you are destroying 555's, you will probably destroy a Stamp. Switching HV creates *mean* voltage spikes that can eat a Stamp easily.
One place you might look for more information is the Tesla Coil Mailing list. Look at hot-streamer.com to subscribe. I remember that a year or two back the moderator made a triggered spark gap for a Tesla coil with a Stamp, so he would know about interfacing it. The guy is literally a genius and a very nice·person to boot. Plus the group has many very smart HV folks.
Jonathan
www.madlabs.info
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Just noticed the "think Jacob's ladder" line. For a JL, you could use a dimmer switch for a fan (not one for a light) and run the IC from the mains. There are plenty of schematics out there for that. But, for a good JL, the IC will be a little weak. An oil burner ignition transformer or a neon sign transfromer woould be a better choice. Both of those transformers can handle a dead short, which is basically what a JL is.
Jonathan
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Thanks. [noparse]:)[/noparse] I've been reading the DigiKey site since you posted that.
Jonathan,
I didn't post exactly what I'm doing, because I didn't want anyone to pass me off as a nut right off. [noparse]:)[/noparse]
There are a whole bunch of conceptual things floating around the net about running a car on hydrogen through electrolysis. I've been playing with different things, to see if any of them may work. I'm not sticking exclusively with the unconfirmed stuff, I'm reading a lot of actual research on electrolysis.
I'm trying to stay somewhere close to what can be reproduced in a car, hopefully with the least equipment possible.
I've been playing with different voltages, with some interesting results. Some of the sources I found said to stay near 2vdc, while most of the rest are suggesting to stay with the 12VDC native to a car. I was less than impressed with the results. On a whim (since I don't believe half of what I find on the Internet), I started going higher with the voltages. With a little bench power supply, I stepped from 2VDC to 30VDC. The higher I went, the better the results. Then I managed to find a few references from lab work saying the higher the voltage the better.
I tried 110VAC, just to see what would happen. It was run through a series of circuit breakers. If it were to short badly, it would pop one of them. [noparse]:)[/noparse] It didn't pop the breaker, but it also didn't produce any hydrogen. It did heat the water nicely though. That conflicts with everything I've read, which is a bit confusing.
I got a 400V 30A bridge rectifier, to make 110VDC out of 110VAC. (ok, more like 130V). That was nice, except for the way it popped one of my circuit breakers after about 5 seconds. It was bubbling very well. Unfortunately, it was drawing 14A, which my wires didn't like. I reduced the level of water in the box, and made it run at 6A for a few minutes. The wires still didn't like it, but it bubbled very well.
What has really drawn my attention is the effect of high voltages through water. Aparently, once you reach a particular voltage (140v or so), something spectacular happens. You get a light bigger than just a plasma arc, and rapid decomposition of the water. Now, that's only what I've read. I haven't reproduced it yet. I'm trying to skip way up the scale, by using an automotive coil (Accel Super Coil), which puts out 45kV
To drive the automotive coil, I need to do just like a car does. It pulses 12VDC on the input side, to produce the HV output. The spec on this ignition coil says it's good to 6500 RPM, which on a v8 engine would be 866 Hz.
I like Mike's suggestion, so I'll keep looking into them, to isolate my circuit.
I'm not really great with dealing with all the components, especially where the 555 chip still seems like black magic to me. [noparse]:)[/noparse] It's quite likely in my frustration, I hooked things up wrong, and created too much of a load through the 555 chip. I've burnt out 2 so far, and my most recent unsuccessful test was with a fresh one. The sad part about the attempts with the 555 chip is, I never hooked it up to the coil. I was driving a LED and a small speaker.
It took me days to get that even remotely right (talk about frustration). I picked up the basic stamp HomeWork board at Radio Shack, and within about 10 minutes, I had both a LED and the speaker working, which means I know I can make the pulse signal successfully, without wondering what else is wrong. I can also adjust the pulse rate as needed. I was ready to just try hooking the coil up to the transistor that I'm running a second LED with right now. I already knew, that would blow something out. I just wasn't sure what the best course of action was to do with it from there, to make the voltage, without blowing anything up.
By no means is this attempt the last I'll be doing with the BS. I've been threatening to do a lot of interesting things for years. Until now, I was missing that little piece in the middle. How do I make my programming skill work real-world objects? [noparse]:)[/noparse]
I'll be keeping a close eye on this thread, oh yea.
You've been called a nut, or you're calling me a nut? [noparse]:)[/noparse]
I'll try to keep the explosions down to a minimum (I like the exploding emoticon, hehe) I've been slowly seperating the on/off switch from the box, just in case. Right now, it's about 10 feet away. All I've managed is a little smoke and a brief spark from the components I've burnt out. I guess that's not a very good thing, considering while it's working (before the parts burn up), I've generated at least some hydrogen. I guess it's good that hydrogen rises. [noparse]:)[/noparse]
I have played quite a bit with electrolysis with the intent of producing hydrogen to be used in a fuel cell powered robot. I was working with low voltages as I was planning on using solar panels. I built a couple of pretty decent perforimg sealed units, but boy is it a PITA....
Anyway, this is way off topic for this forum, but if you would like to contact me off list jpeakall AT madlabs DOT info, please do. I be happy to share what I know.
And I just let 'em call me nuts. Mad scientist and proud! Muhahahaha!!!
Jonathan
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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot