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View Full Version : Help! Can't figure out what's wrong with a circuit I've built.



ddrinkle
03-19-2008, 02:08 AM
Hi there,
First I need to say that this question doesn't have much to do with Christmas Lights, nor does it have a lot to do with the Olsen 595, however I figure you guys probably have the most experience with the 595 circuits, and the circuit I'm having trouble with is based on the 595 design, I thought it might be appropriate to ask you guys a question, if not.. I appoligise in advance.

Ok, I've designed a PCB for controlling the lighting of fireworks, using a computer, it's a pretty simple process, and similar to lighting christmas lights, except that when I turn on a switch, it's generally going to be on for about 2 seconds, then it's off. With that said the circuit I've designed can light 192 individual fireworks using a series of 595 controllers. 1 controls 8 common grounds, the second controls a "bank", and the third controls "slat"... 8*3*8 = 192.

Here's the circuit...

Here (http://www.thedrinkles.com/images/firing_circuit.jpg).

The problem I'm having is as soon as I plug in the 12v (I don't dare try 24 yet) the 595 Shift Registers get blazing hot. This is even when nothing else is plugged in. I've tried everything including removing the MOSFET's, disconnecting the Pull-up resistors, removing the ULN2308's, and the two right most 595's... and still the remaining 595 gets really hot.

The one thing I haven't tried is to reverse the direction of Diode 1 and Diode 2. The only reason I haven't done this is that my test circuit (using a bread board) works PERFECTLY with the diodes like they are in the diagram.

For those of you who don't follow the circuit, this system controls 8 cues/bank, 3 banks/slat (24 cue's per slat), and 8 total slats for a total of 192 cues.

Any help would be greatly appreciated. I know this is pretty off topic... but I'm really hoping one of you could help me out.

Thanks

RavingLunatic
03-19-2008, 07:11 AM
Are you applying 12VDC to the 595 chip? If so, what is the part number?

The 595 chips that I have datasheets for all have a maximum VCC of 7 VDC, that could be why they are getting hot.

ddrinkle
03-19-2008, 07:17 PM
The problem was the diodes.. they were put in wrong.. problem solved... Thanks

ppohlman
03-20-2008, 03:53 PM
Sounds like an interesting design. If you want to go into more detail and explain your setup, feel free to continue in the "Other Holidays" section. There are a few of us around that have some firework experience.

ddrinkle
03-20-2008, 04:03 PM
Sounds like an interesting design. If you want to go into more detail and explain your setup, feel free to continue in the "Other Holidays" section. There are a few of us around that have some firework experience.

Once I get it working I certainly will. Right now I got rid of the heat problem, but still have a problem of some of the cue's lighting when they aren't supposed to be.

Ronp
03-20-2008, 05:06 PM
controlling fireworks with a 595 Hmmm I hope you have thought of the random fireing that takes place when the 595 is first pluged in to the pc and also when the 595 is left on channels come on randomly.I would not recommend using the 595 for fireworks...
Some type of saftey should be in place...But thats just my worthless 2 cents........

ben
03-20-2008, 05:53 PM
controlling fireworks with a 595 Hmmm I hope you have thought of the random fireing that takes place when the 595 is first pluged in to the pc and also when the 595 is left on channels come on randomly.I would not recommend using the 595 for fireworks...
Some type of saftey should be in place...But thats just my worthless 2 cents........

I was actually thinking of using the Grinch controller and have 64 channels of fireworks and use Vixen to do it to the beat. I use E-matches and it only takes like .5A to light them. Does the Grinch have this problem.

Ben

Wayne J
03-20-2008, 06:32 PM
gonna be hard to do when the IC's only have 90mA a channel.

Macrosill
03-20-2008, 06:52 PM
Please see the following thread! http://www.doityourselfchristmas.com/forums/showthread.php?t=2254&highlight=pyrotechnics

ddrinkle
03-20-2008, 06:55 PM
controlling fireworks with a 595 Hmmm I hope you have thought of the random fireing that takes place when the 595 is first pluged in to the pc and also when the 595 is left on channels come on randomly.I would not recommend using the 595 for fireworks...
Some type of saftey should be in place...But thats just my worthless 2 cents........

Yes, I've thought of all of that. Outside of what the above circuit board has, the system is build to key-locked switches, so no power is going to the fireworks, until I turn the key to the arm position... which will happen way after I've plugged in the PC, run a series of 0's through the 595's to clear them out etc. Additionally the randomness of the 595 can be signifcantly reduced buy using pull-up/pull-down resistors on the input channels... which I've done in another part of the system closer to the PC.

With all of these modifications, I think it's safe to use the 595 with fireworks... correct me if I'm wrong... PLEASE!

ben
03-20-2008, 07:25 PM
gonna be hard to do when the IC's only have 90mA a channel.

Wayne thank you for pointing that out. I actually looked and I thought they were 50mA but they are .75A. I could just make a simple transistor board.

Ben

ben
03-20-2008, 07:38 PM
Please see the following thread! http://www.doityourselfchristmas.com/forums/showthread.php?t=2254&highlight=pyrotechnics

Brian, I just want to say my father has a Low Explosives User Permit. He has been trained in the handling of explosives and fireworks. I was able to earn an "honerary" permit since my father signed a waiver and the such so I am also licensed. I have read and understand that the software they use for pyrotechnics is close to what we use. I am a member or pyro universe. They are very helpful. You can easilly and safely use fireworks in a light display. I plan on incorperating some into mine. I will have a voice over saying fountains are used in this display please do not cross the boundry (which will be very tall but "porous" ) and I will basically have one song or display that I run at a couple intervals that I there outside to arm the system and it will be ran on a completely different computer with manual overides and power cutoffs.

Ben

Macrosill
03-20-2008, 08:09 PM
All well and good Ben but discuss pyrotechnics on the other forum, not here.