colniko Posted June 9, 2008 Posted June 9, 2008 There is probably a very simple explanation/fix for this, but as of now I am stumped. I constructed an electric firing box using three 9v batteries in series. I am pushing this down 100 feet of speaker wire and using 32 gauge nichrome wire as the igniter. All seemed to work "relatively" well except the batteries die kinda fast. So I added a fourth 9v battery to the mix, tested the V's and amps with a multimeter (everything seems to be right on. 36v and like 14amps) at the end of the 100 foot wire. Here, however, is the SNAFU. Now it will not fire. The NiCr does not even heat up, or if it is, very little. And this is connecting the lead and NiCr directly to the firing box. I assumed after seeing it mentioned in a post here that I was adding too much resistance with the addition of all the connecting wires to each 9v, so I removed the default small wires and soldered on larger 24 gauge wires to each battery connector. Still nada. I connected the lead/NiCr directly to a single 9v and all fires correctly. So at this point it seems to be with the addition of that fourth battery. What am I missing here? I am horrible at math, so have not even bothered with the I=v/R equation (yes, I am sure some math/electronics major is going to correct that equation.. it was just to make a point) I am sure I am forgetting something in the description above that is important to solving this... Edit: Correction to the speaker wire size for the battery connects. I stated 24 gauge when in fact it is really 18 gauge speaker wire.
Bonny Posted June 11, 2008 Posted June 11, 2008 Doesn't seem to be any help flowing in on this one... I can't see any reason that the igniter would fail with the extra battery.I think in any case using 3 or 4 batteries they will still die pretty fast. i think your best plan is to change batteries. Maybe look at trying a system using 6V lantern batteries, they can be wired in series for 12V or 18V, and they will last longer. Or better yet, go with 6V or 12V rechargeable batteries, like those used in motorcycles or even emergency light systems. My system uses 2 6V emergency light batteries in series for 12V and works fine.
50AE Posted June 11, 2008 Posted June 11, 2008 Can't you use a lower voltage batteries ? Something like 2x1.5 V, D type (the big ones). They have more juice, and 3V should be enough for small igniters (1 cm nichrome wire)
colniko Posted June 11, 2008 Author Posted June 11, 2008 Yeh, I don't know why it doesn't work. Odd. I will keep messing with it. I know I should use a larger battery, but I had visions of having a small handheld firing box and as such purchased a 4inch project box from rat shack. Someone had mentioned possibly trying nicad or nimh batteries. I will keep playing with it. Thanks for the suggestions.
ST1DinOH Posted June 11, 2008 Posted June 11, 2008 There is probably a very simple explanation/fix for this, but as of now I am stumped. I constructed an electric firing box using three 9v batteries in series. I am pushing this down 100 feet of speaker wire and using 32 gauge nichrome wire as the igniter. All seemed to work "relatively" well except the batteries die kinda fast. So I added a fourth 9v battery to the mix, tested the V's and amps with a multimeter (everything seems to be right on. 36v and like 14amps) at the end of the 100 foot wire. Here, however, is the SNAFU. Now it will not fire. The NiCr does not even heat up, or if it is, very little. And this is connecting the lead and NiCr directly to the firing box. I assumed after seeing it mentioned in a post here that I was adding too much resistance with the addition of all the connecting wires to each 9v, so I removed the default small wires and soldered on larger 24 gauge wires to each battery connector. Still nada. I connected the lead/NiCr directly to a single 9v and all fires correctly. So at this point it seems to be with the addition of that fourth battery. What am I missing here? I am horrible at math, so have not even bothered with the I=v/R equation (yes, I am sure some math/electronics major is going to correct that equation.. it was just to make a point) I am sure I am forgetting something in the description above that is important to solving this... Edit: Correction to the speaker wire size for the battery connects. I stated 24 gauge when in fact it is really 18 gauge speaker wire. some more info would be helpfull... first off whats the situation on resistors and diodes? it seems rather odd to me that the 9volts were dying so quickly with 3 in the system. how many cues? what type of systemis this...is it a common ground system, a multi/selectable ground? are you using push button momentary switches or are you using throw switches? is there a continuity circut, and if so, what are you using for indicator lamps? have you checked your internal circuts yet for any shorts, if the 9v's are dying that fast there may be a short and if so you'd probably notice them getting kind hot when you hook it up. try hooking it up with fresh batteries, leaving the system off, and after like 10 minutes feel the 9v's and see if they are warm (or hot). if so you're dumping juice somewhere and you'll need to take a look at each leg of the system and hunt it down. if you don't have diodes on the back side of each cue (in a multi cue system) this can cause problems...not sure if that would include the problem you are having but it's something to think about. you may also try using some different sized resistors to dial in what works perfect for you. but thats only if all the legs of the system are not shorting and working just right. here's another stupid question... whats the enclosure made out of? i saw a case where the metal enclosure was actually causing the short, so out of the box everything works perfect, but once re-mounted into the enclosure/project box the problem re-surfaced. --- i know i didn't specificly help you much at all, but hopefully i gave you at least one idea that you hadn't looked into yet and this helps you solve the problem. electronics can be a real PITA when something isn't working. youwind up spending more time fixing them than building and designing them. they are great when they work right, but when they dont i just wanna chuck em in the river.
colniko Posted June 14, 2008 Author Posted June 14, 2008 > some more info would be helpfull... >first off whats the situation on resistors and diodes? None. It's a very simple box >it seems rather odd to me that the 9volts were dying so quickly with 3 in the system. When I say dying I mean dropping within a few volts at best. Voltmeter readings of between 7.x to 8.x volts. I just wanted to eliminate any issues by always using fresh batteries. >how many cues? Only one. >what type of system is this...is it a common ground system, a multi/selectable ground? Is as simple as it gets. Project box, Four 9V batteries in series, connected with 18 gauge wire connected to a press button and the speaker terminals. Nothing even remotely fancy. No LEDs, no on/off, no safety switch. >are you using push button momentary switches or are you using throw switches? Push button momentary. >is there a continuity circut, and if so, what are you using for indicator lamps? None >have you checked your internal circuts yet for any shorts, if the 9v's are dying that fast there may be a short and if so you'd probably notice them getting kind hot when you hook it up. No shorts. No heating of batteries. >try hooking it up with fresh batteries, leaving the system off, and after like 10 minutes feel the 9v's and see if they are warm (or hot). Negative >here's another stupid question... >whats the enclosure made out of? Plastic. All internal connecting wires are good too. No exposed wires to cause any shorts. Anyone have any thoughts on what is more important, Amps or Voltage? Someone made the suggestion to me that I use a combination series/parallel hookup to double voltage and current. I haven't had time to try it yet but at this point willing to try just about anything. And again, thanks for the tips and suggestions.
GalFisk Posted June 14, 2008 Posted June 14, 2008 I know those small 9V batteries are crap for applications such as this. As long as you have sufficient voltage, you want to focus on getting as much current as possible. If the nichrome burns at 9 volts, you can connect several batteries in parallel. But the best would be to use lead-acid or NiMH rechargeables, which can deliver the required current.What is the result of the following measurements:resistance of nichrome wireresistance between battery terminals when nichrome is connected and firing button pushed (the batteries should not be connected)Voltage across the nichrome wire when the button is pushed and the unit malfunctioning (ie the wire should burn but doesn't)Voltage across the batteries when the button is pushed, and when it's not
colniko Posted June 27, 2008 Author Posted June 27, 2008 GalFisk: Sorry, didn't mean to blow you off, I haven't really been playing with that firing box the past week but plan on trying to get to it this week. Also, I don't know the answer to all the questions you asked. I will work on them though. I have a strong feeling that simply changing it to a series/parallel connection and switching out from 18awg to 14awg is going to solve the problem.
ST1DinOH Posted June 27, 2008 Posted June 27, 2008 > some more info would be helpfull... >first off whats the situation on resistors and diodes? None. It's a very simple box >it seems rather odd to me that the 9volts were dying so quickly with 3 in the system. When I say dying I mean dropping within a few volts at best. Voltmeter readings of between 7.x to 8.x volts. I just wanted to eliminate any issues by always using fresh batteries. >how many cues? Only one. >what type of system is this...is it a common ground system, a multi/selectable ground? Is as simple as it gets. Project box, Four 9V batteries in series, connected with 18 gauge wire connected to a press button and the speaker terminals. Nothing even remotely fancy. No LEDs, no on/off, no safety switch. >are you using push button momentary switches or are you using throw switches? Push button momentary. >is there a continuity circut, and if so, what are you using for indicator lamps? None >have you checked your internal circuts yet for any shorts, if the 9v's are dying that fast there may be a short and if so you'd probably notice them getting kind hot when you hook it up. No shorts. No heating of batteries. >try hooking it up with fresh batteries, leaving the system off, and after like 10 minutes feel the 9v's and see if they are warm (or hot). Negative >here's another stupid question... >whats the enclosure made out of? Plastic. All internal connecting wires are good too. No exposed wires to cause any shorts. Anyone have any thoughts on what is more important, Amps or Voltage? Someone made the suggestion to me that I use a combination series/parallel hookup to double voltage and current. I haven't had time to try it yet but at this point willing to try just about anything. And again, thanks for the tips and suggestions. as simple as that box is i cannot for the life of me figure why the hell you are having any problems. i now share in your frustration and wish you the best of luck, i'm no help beyond all that stuff i posted. ohm's law and i don't get along very well so diagnosing the power problem beyond a design/setup standpoint is nothing i can even begin to help with. if this helps at all...my system uses a 12 volt 1.3 amp rectangle shaped power source. i don't have any problems. you may want to ditch the 9volts and go with something different till you firue out what the hell is going on. quite the mystery indeed.
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