Does anyone know how much current is required to fire an estes ignitor? I'm working on a simple g-activated timer for a second stage airstart, and being a tightwad doityourselfer, I'm building 1 myself. Trouble is, the 556 chip I'm basing it on puts out a maximum of 200mA and I'm not sure if this will be enough. I think it will fire e-matches but I can't seem to find any info about estes ignitors. I'm picking up what I need on Monday and would like to get everything I need in 1 trip. Thanks in advance!
ignition current
- Thread starter Ouly
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rstaff3
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Ouly,
I don't really know many 'specs' about the Estes ignitors. I've only seen measurements of the peak current draw when hit with 12v, which is over 12A. But this is not the minimum required to light them.
However, I would recommend you add a power transitor driver whatever you do. 200mA is not enough to reliably ignite any ignitor I know of. That does not mean it may occasionally work with some of the low current ignitors, but the range at which these ignitors are guaranteed to fire is around double that. If you use a good 9v battery and add a power transitor, you should be able to fire the Estes ignitor as well as e-matches.
I don't really know many 'specs' about the Estes ignitors. I've only seen measurements of the peak current draw when hit with 12v, which is over 12A. But this is not the minimum required to light them.
However, I would recommend you add a power transitor driver whatever you do. 200mA is not enough to reliably ignite any ignitor I know of. That does not mean it may occasionally work with some of the low current ignitors, but the range at which these ignitors are guaranteed to fire is around double that. If you use a good 9v battery and add a power transitor, you should be able to fire the Estes ignitor as well as e-matches.
Thanks rstaff3. I figured I would have to add the power transistor or small relay but was hoping not to. I'm what you might call "electronically challenged" so I didn't design the timer from scratch. The design I'm using has a HEXFET (IRFD110) that is triggered by the output of the 556 timer which in turn dumps the power from a 1000uF capacitor into the ignitor. The person who initially designed this uses flashbulbs and suggested I remove the capacitor and replace it with a second batt. I'm hoping to use a single 9-volt batt. instead to run both the timer and firing circuit but the power transistor has to trigger with <200mA yet handle the current that the ignitor draws. Does such a thing exist or do I need to go to a relay? I haven't been able to find out much about the IRFD110 yet so I don't know if it can do the job or not.
rstaff3
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You will not have a problem getting a power transistor that can be triggered with logic-level voltages from an IC with that current. The power the transitor can switch has nothing to do with the way it triggers.
I don't know what local sources you have but you can order online from Digikey (and many other sources too). The ZVN4206A and IRL510-ND MOSFETs are two examples that have been successfully used and are available from Digikey.
If it was me I'd keep the cap. One problem with one battery is the voltage will sag when the match fires. This can disrupt the electronics. It is probably more of a problem if you are using a processor vs. a simple timer.
I used to have a link to a timer project but can't find it. Sorry.
Good luck!...and keep us posted on your progress...
I don't know what local sources you have but you can order online from Digikey (and many other sources too). The ZVN4206A and IRL510-ND MOSFETs are two examples that have been successfully used and are available from Digikey.
If it was me I'd keep the cap. One problem with one battery is the voltage will sag when the match fires. This can disrupt the electronics. It is probably more of a problem if you are using a processor vs. a simple timer.
I used to have a link to a timer project but can't find it. Sorry.
Good luck!...and keep us posted on your progress...
Thanks again Dick for the suggestions! The IRL510 may be just what I'm looking for. I wasn't happy with the IRFD110 because it could only handle switching 1 amp if I got my info straight. Good point too about the capacitor. I hadn't really thought about possibly interrupting the triggering pulse just as the ignitor starts to draw current. Only time and testing will tell.
I'll try to keep you up-to-date but it may be awhile as I have to do some actual work this week. I've got an order for some of my woodwork and as funds are running low, it's probably in my best interest to get at it.
I did finish my first scratch built rocket but haven't flown her yet. I'll get a pic or 2 once I borrow a buddy's digital camera but I'm not real happy with the finish. The paint went on fairly well but the clearcoat is a mess. It went on sort of pebbly. I think the temperature was too cool for it. I couldn't get it to flow together and it was almost impossible to put on too heavy. Before I knew it, I was out, and this is how she stays unless I try another can on a much warmer day.
That's all for now and thanks again.
- Mark
I'll try to keep you up-to-date but it may be awhile as I have to do some actual work this week. I've got an order for some of my woodwork and as funds are running low, it's probably in my best interest to get at it.
I did finish my first scratch built rocket but haven't flown her yet. I'll get a pic or 2 once I borrow a buddy's digital camera but I'm not real happy with the finish. The paint went on fairly well but the clearcoat is a mess. It went on sort of pebbly. I think the temperature was too cool for it. I couldn't get it to flow together and it was almost impossible to put on too heavy. Before I knew it, I was out, and this is how she stays unless I try another can on a much warmer day.
That's all for now and thanks again.
- Mark
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