Doorbell button as switch for ematch

[vizzer]

I've got a 6V battery hooked to a doorbell as a switch for some basic electric matches. The doorbell lights up to let people know where it is at night.

 

I've just read that analog multimeters can fire an electric match. Any thoughts on the doorbell leaking enough electricity to light the ematch? It's flat copper strand from a scrub pad stretched across a strike anywhere match.

 

John

[Col]

It`ll take a fair amount of current to heat the wire enough to ignite the match. The copper wire may well burn out before it lights the match.

Edited January 14, 2015 by Col

[dagabu]

I've got a 6V battery hooked to a doorbell as a switch for some basic electric matches. The doorbell lights up to let people know where it is at night.

 

I've just read that analog multimeters can fire an electric match. Any thoughts on the doorbell leaking enough electricity to light the ematch? It's flat copper strand from a scrub pad stretched across a strike anywhere match.

 

John

 

Yes, the bulb will draw enough power to light a REAL E-match. I have an ODA Blaster Box that has a light, it is on the circuit board and not part of the firing circuit. I also have a cheap multimeter that if I use it to measure continuity across the leads on a 50g e-match, it will fire it while my digital one at work will not fire them.

 

The strike-anywhere match? Only one way to find out, test it.

[vizzer]

Thanks. It's worked fine pressing the button, and nothing's gone up spontaneously otherwise. So far.

 

But I think I'll just switch to the unlit doorbell variety.

 

It's kind of different, being at this end of the learning curve on things again. Thanks to you all for the knowledge and help.

 

John

[MrB]

Separate the button from the match with a relay?

B!

[Col]

relays can be hazardous in a firing system Best bet is to use a keyswitch with one position selecting the very low current circuit (a few mA) for continuity testing and another position for giving it full beans.

Edited January 14, 2015 by Col

[GalFisk]

It's different if the button has an old-fashioned filament lightbulb or a modern LED. LEDs run maybe 5-20 mA, while light bulbs use several hundred mA. In many cases, the light source can also be removed form the button.

[MrB]

relays can be hazardous in a firing system

Shouldn't be a problem when it's put together with the button. As far as i know it's the physical shock of the launches that may trigger unwanted results, and the button should be well away from any mortar tubes, so that should be a "none issue"... But your right, a different switch is the better alternative. I was just giving an option that lets him keep his current button since he seams to like it.

B!

[vizzer]

I love that button, but if it has to go or be ... cut ... then so be it.

 

Thank you for the options.

 

 

John

[Arthur]

Measure the current! 20mA is a safe current for a 50g commercial ematch.

[vizzer]

Measure the current! 20mA is a safe current for a 50g commercial ematch.

I'll do that. You know, I work in solar, but I'm not the electrical engineer. So I have a multimeter but it rarely crosses my mind to use it.

 

As Homer would put it: D'oh!

[Arthur]

For professional 50g igs the safe no fire current is about 50mA so most systems limit to 20mA for continuity checking. The sure ALL fire current is 500mA so it's best to allow for 1 amp, this way you come as close as possible to 100% no fire when testing and 100% all fire when needed. Having a circuit capable of providing 1 amp ensures that the igniter fires as quickly as possible (about 20milliseconds)

 

For DIY igniters it's hard to guess the figures, you need to do some tests

[vizzer]

For professional 50g igs the safe no fire current is about 50mA so most systems limit to 20mA for continuity checking. The sure ALL fire current is 500mA so it's best to allow for 1 amp, this way you come as close as possible to 100% no fire when testing and 100% all fire when needed. Having a circuit capable of providing 1 amp ensures that the igniter fires as quickly as possible (about 20milliseconds)For DIY igniters it's hard to guess the figures, you need to do some tests

Thanks.

 

These are definitely DIY electric matches. It's probably, but not certainly, not an issue; the doorbell didn't light up until I had two 6V batteries in series, fwiw, so I didn't put 1 and 1 together until I saw that about the analog meter.

 

My business partner undoubtedly has a rheostat I can use to dial up the current and see where the safety matches light. I guess I should start a notebook too.

[Col]

The 6v battery should provide enough current to melt the wire, whether it ignites the match is another question but you dont need a rheostat. Limiting the current is only necessary for testing continuity of the e-match prior to firing it. In your case, theres no continuity checking so its not an issue. The light in the doorbell switch will simply hook across the supply to illuminate the housing, its not part of the switching circuit.

[vizzer]

So basically this is the setup which everyone probably already imagined it would be like: pretty basic.

 

This is my first upload BTW (if it works), and in the future I'll just try to link things.

In this setup the battery isn't even supplying enough current to light the doorbell.

 

I think the light in the doorbell lets some electricity bypass the button, completing the circuit and so potentially heating the copper pulled across the match head. The idea behind the rheostat was just to be able to really test and see at what current the match will light. Then I'd have a quantified result. Otherwise I could just hook everything up, without pushing the button, and see if it eventually lights, and do that with a number of matches.

 

As an aside, this really seems like a LOT of help on a really small issue. I don't want to take up a lot of time with something that's probably insignificant. That is, I really appreciate all the help and advice, but I don't want to take away from folks with the "big" questions.

 

That certainly doesn't mean stop sharing your thoughts! And thank you.

 

 

John

[Col]

Hi John

Your multimeter will tell you if there`s any voltage across the switch when its open circuit (not pushed). Judging by the time it took to ignite the match it needs a fair amount of current.

[patsroom]

Here we have a very simple firing switch. It works, I use it all the time when I need to fire e-matches.

For a easy handle I use a diameter of PVC pipe 6" or so long that feels comfortable in my hand.Then I get a PVC cap that fits and drill two hole in it for the LED and (I use a small push button type) switch. I should have added a diode to the circuit to keep from being able to place current in reverse. (It could fire without telling you if there is a current.) It can fire because it will just pass up the LED when you press the fire button. The LED can act kinda like a diode in a way when reversed but will not light up.

Now if you wired it up right there you go!

What happens is just enough current lights the LED but not my Christmas light bulb e-match, this is done by lowering the amperage in the current by using a resistor in that part of the curcuit . I have left the current on with my home made e-match in place for a long period of time with no firing of the e-match, not even warming it.( As always test your system before trusting it.) With the LED lit it shows that the curcuit is complete and working. But that is not saying that there is not something wrong going on in the system. Just that the current is going from point to point of the electric positive to negative polls. (Understanding the system helps make it work.) Now by pushing the fire button which will allow the current to by pass the LED curcuit part of the system and now allow a higher amperage to travel to the e-match.

It's simple direct and it works. It is my hopes that this tad bit helps someone along the way................Pat

A Go No-Go firing Switch.bmp

[Col]

Good idea Pat

He might be able to graft the led into the doorbell housing in place of the 6v lamp. A 220ohm 1/4w (5%) resistor on the led will do the trick (2v @ 20mA)

[vizzer]

This is great. Many thanks. Life intervenes...home solar project for the near future as propane tank arrives today and backup generator needs to be (bought and) put into the system.

[Arthur]

Pro igniters have a resistance of about 1.5ohms, they will pass 50mA without ever firing and at 300mA they will all fire, to make them fire quickly we like to pass 500 - 1000mA then the ig is gone in 20 milliseconds.

 

The advantage of this is that they will fire at the end of a length of twin flex, giving some safety distance for the firer.

 

I have some confetti cannons that take 8 amps for 1 second to make them fire the 12v battery has to be within 18" of wire of the cannon for them to fire. NOT what you want for pyro.

[patsroom]

Good idea Pat

He might be able to graft the led into the doorbell housing in place of the 6v lamp. A 220ohm 1/4w (5%) resistor on the led will do the trick (2v @ 20mA

The reason I never gave a resistor value is because it is related to the requirements of the LED and the level of power source voltage being use, as it can vary from a few volts to even a hundred I suppose.

[Col]

He used a 6v battery in his test A forward voltage of 2v is enough for most common red/green/yellow leds, a blue would need more.

[patsroom]

He used a 6v battery in his test A forward voltage of 2v is enough for most common red/green/yellow leds, a blue would need more.

 

 

 

Yep yep, I seen that too and you are right for his requirement. But to make this system useful for those who want to use it, they should remember that the resistor will needs to match their power requirements.........Pat

 

PS - I forgot to add that this circuit is also useful to make a hard wire firing system that can have as many cues as needed.

Edited January 21, 2015 by patsroom

[Col]

Aye, i figured vizzer may be in a rush to get it done, hence the resistor value for his supply voltage

Depending on how many cues you want, its better to use multiple grounds for hard-wired systems ,diodes are cheaper than copper wire. I use a single cat5 cable (4 pairs) for 15 cues, i could have gone for 16 but 4 banks of 4 cues seemed a bit clunky.

 

http://www.amateurpyro.com/forums/topic/10332-wired-firing-system/?do=findComment&comment=136904

 

With two cat5 cables you`d get 64 cues which is plenty for a small show. Apart from the savings on cable you also reduce the number of switches required and its a smaller package. The addition of a keyswitch is a good idea for safety...some people cant resist pressing unattended red buttons

Edited January 21, 2015 by Col

[patsroom]

That is the exact reason why they don' invite me to the White House. To many red buttons so little time ...............Pat

Edited January 21, 2015 by patsroom