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Model Forum / General / Rockets / September 2004Newbie question (launch controller)
Hi guys, New to the sport, new to the group, this is my intro post. Bought a Quest super eagle kit to fly with my son, recently built and test flew a Estes High Flier, and we're starting to look at other kits, and 'stuff'. First thing on my 'stuff' list is a new launch controller, and I'm going the DIY route. As much as I like Quest's little pistol grip launch controller, I want something a bit more robust (the launch key conctacts are very suspect). So, I'm plannning on scratch building one and have been scrounging the internet for plans, that I will modify to suit. I'm not an electronics whiz, but I think I can pull this off. Probably going to build a 3 station (switchable) remote 12 volt box, with the usual safety key, continuity checker components. I'd also like to incorporate a panel battery test meter (ala Pratt SureFire or a St Josephs' ELC-50, which looks neat), but I'm a little ignorant here as to the specific meter and relevant circuitry. Is it more relevant to measure voltage or amps (both?)? Additionally, aren't these meters really only relevant when they read while under load? If so, do you have to design a separate circuit to simulate load when you switch on the meter? Like I said, electronics is not my strong suit. any guidance, hints, common pitfalls appreciated. Mark > Hi guys, > > New to the sport, new to the group, this is my intro post. Warning. Run away! > Bought a Quest super eagle kit to fly with my son, recently built and > test flew a Estes High Flier, and we're starting to look at other [quoted text clipped - 19 lines] > > Mark  SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring common sense back to rocketry administration. Produce then publish. http://www.usrockets.com My articles valuable? Donate http://tinyurl.com/2hmgv Yeah, well.... I've been reading your posts, and the ones from the rest of the band of merry men that bash each other on the head about how fun the model rocket industry is, and what really swell guys you all are. Its all really terrific stuff and bodes really well for the health of the hobby. (blink, blink), really... TTYL Mark > > Hi guys, > > [quoted text clipped - 32 lines] > Produce then publish. http://www.usrockets.com > My articles valuable? Donate http://tinyurl.com/2hmgv > Yeah, well.... I've been reading your posts, and the ones from the rest of > the band of merry men that bash each other on the head about how fun the > model rocket industry is, and what really swell guys you all are. > > Its all really terrific stuff and bodes really well for the health of the > hobby. (blink, blink), really... I personally think you have hit on the central issue in rocketry today. Jerry > TTYL > [quoted text clipped - 36 lines] > > Produce then publish. http://www.usrockets.com > > My articles valuable? Donate http://tinyurl.com/2hmgv SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring common sense back to rocketry administration. Produce then publish. http://www.usrockets.com My articles valuable? Donate http://tinyurl.com/2hmgv > Hi guys, > > New to the sport, new to the group, this is my intro post. Howdy... > I'd also like to incorporate a panel battery test meter (ala Pratt > SureFire or a St Josephs' ELC-50, which looks neat), but I'm a little [quoted text clipped - 4 lines] > switch on the meter? Like I said, electronics is not my strong suit. > any guidance, hints, common pitfalls appreciated. Common pitfalls? The KISS rule always applies.... Your goals should always be paramount and focused upon... and be subject to moderate change. If your goal is to Learn electronics with your son... then building a launch controller is a good first step... it can lead to all kinds of controllers... camera, staging, apogee detection, deployment, etc. If your goal is to build rockets (learning the art of fabrication) then great! Composite construction, sanding, drilling, sawing, fiberglass, carbon fiber, glues, geometry. If your goal is to fly rockets (learning the Science of aerodynamics) then great! If your goal is to is just to spend time with your son and others of like mind in the great outdoors... then you've chosen the perfect hobby! That said... purchase Doug's (or another's) launcher unless you wish to learn and teach your son electronics... personally... I'd build and fly a bunch using Doug's controller until you find that your son and you find reason to abandon it and go for something more suitable to your needs. I think you'll find that there are more interesting electronic pursuits to follow when you and your son are ready. > > Hi guys, > > [quoted text clipped - 38 lines] > I think you'll find that there are more interesting electronic pursuits to > follow when you and your son are ready. Doug and St Josephs have cool loking stuf, but thats not how I want to do this. Sorry its the hacker imperative in me, I want to try and figure this out, try and geek something workable, and have it be something I did. I've got a picture of it in my head, I just want to see if I can pull it off with my limited engineering skills (and learn something in the process). Mark > Doug and St Josephs have cool loking stuf, but thats not how I want to do > this. Sorry its the hacker imperative in me, I want to try and figure this > out, try and geek something workable, and have it be something I did. I've > got a picture of it in my head, I just want to see if I can pull it off with > my limited engineering skills (and learn something in the process). Perfect! I can truly relate to the hacker imperative!!! For a battery check, you want a push-button that will apply a (resistive) load... so yes, a seperate 'battery check' circuit is needed... keep in mind that every time you check the battery, you will be draining it a bit! The meter you use is up to you, but I prefer the digital types... the load circuit is simple as long as Ohms law is followed (P=I*E) and you don't burn up your load. There's a whole bunch of schematics out there... it all depends on what type of battery you use, your power requirements, and the amount of time you wish to spend. ;) ... give us more details? > For a battery check, you want a push-button that will apply a (resistive) > load... so yes, a seperate 'battery check' circuit is needed... keep in mind [quoted text clipped - 7 lines] > of battery you use, your power requirements, and the amount of time you wish > to spend. The simplest load test I've found is an automotive taillight bulb. You need to be able to get a bright white light, not just a yellow glow out of the filament. The 1156/1157 draws about 2.1A at 12V and is a good test. For other common bulbs, including the ones in the stock Estes controllers, refer to http://eisner.encompasserve.org/~kaplow_r/bulb.txt Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle: http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org 26-October, 2001: A day that will live in infamy Support Freedom: http://www.indefenseoffreedom.org/ ... One nation under survielence, divisive, with liberty and justice for none. Ahhh... the 'ol "comparative illuminosity check". ;) Good info... Question... aren't bulbs some kind of 'constant current drain' to a power source? Old knowledge... tucked away... can't quite access it... :( > > For a battery check, you want a push-button that will apply a (resistive) > > load... so yes, a seperate 'battery check' circuit is needed... keep in mind [quoted text clipped - 24 lines] > > ... One nation under survielence, divisive, with liberty and justice for none. > Ahhh... the 'ol "comparative illuminosity check". > ;) [quoted text clipped - 6 lines] > Old knowledge... tucked away... can't quite access it... > :( Well, they aren't exactly constant current, but they do have some current-regulating effect... a given increase in voltage won't cause quite proportionally the same increase in current, since the filament has an increasing resistance at higher temperatures. -dave w > > Ahhh... the 'ol "comparative illuminosity check". > > ;) [quoted text clipped - 10 lines] > effect... a given increase in voltage won't cause quite proportionally the same increase > in current, since the filament has an increasing resistance at higher temperatures. Yes, I think that it! Thanks! (May not have been able to sleep with that question bugging me!) >Doug and St Josephs have cool loking stuf, but thats not how I want to do >this. Sorry its the hacker imperative in me, I want to try and figure this >out, try and geek something workable, and have it be something I did. I've >got a picture of it in my head, I just want to see if I can pull it off with >my limited engineering skills (and learn something in the process). As long as nobody gets hurt, even the mistakes are a learning experience. :-) Eldred Signaturehttp://www.umich.edu/~epickett Screamers League IICC League GPLRank -6.0 MoGPL rank +267.80 Ch.Rank +52.58 MoC +741.71 Hist. +82.34 MoH:na N2k3 rank:in progress Slayer Spektera lvl 79 assassin Slayer Spectral_K lvl 44 Necro US East Welcome Mark! You can build your own without too much trouble. Most of what you're looking for can be purchased at Radio Shack. One suggestion. Put together a decent pad too. The easiest way to do it, is pick up a tripod from a thrift store (cheap) and install a drill chuck, to hold the rod. It's a quick and easy way to set up and use multiple rods as your rockets grow in size. Don't pay any attention to all the off ropic stuff on rmr. Despite what you might think, there are a lot of good people here and some even know a little about rocketry. ; ) Randy > Welcome Mark! > [quoted text clipped - 9 lines] > > Randy Thanks, the signal to noise ratio needs tweaking, but hey, its the internet; comes with the turf. So any thoughts on the battery level meter? Volt meter for continuity and voltage the way to go on that? Mark > So any thoughts on the battery level meter? Volt meter for continuity and > voltage the way to go on that? I like a volt meter and they're almost cheap. http://www.radioshack.com/category.asp?catalog%5Fname=CTLG&category%5Fname=CTLG% 5F011%5F008%5F002%5F000&Page=1 Randy > So any thoughts on the battery level meter? Volt meter for continuity and > voltage the way to go on that? four bucks and three meter types: http://www.meci.com/Catalog/Item/73b0affd-a946-4a7c-ad66-ae70f1853ba8 the www.meci.com has lots of surpuls stuff. The Surefire and RTLS launch systems incorporate a battery test circuit that includes a 12 volt DC meter and a resistor that places a load on the battery. You push the Test button and observe how rapidly the voltage drops. The voltage number itself is relatively unimportant; a nearly flat Nicad or Ni-MH pack will read over 12 volts for a couple of seconds. With a load on, it should fall slowly if the battery has a good charge, or drop off a cliff if it's flat. Doug Pratt dad-at-pratthobbies-dot-com > I'd also like to incorporate a panel battery test meter (ala Pratt > SureFire or a St Josephs' ELC-50, which looks neat), but I'm a little [quoted text clipped - 6 lines] > > Mark Hi Doug Any suggestionson what size resisitor might be appropriate? Mark > The Surefire and RTLS launch systems incorporate a battery test > circuit that includes a 12 volt DC meter and a resistor that places a [quoted text clipped - 17 lines] > > > > Mark Depends on the size of your battery pack. It's not critical. For my 3600 mAh nickel metal hydride packs I use a 75 ohm 15 watt sand resistor. > Hi Doug > [quoted text clipped - 23 lines] > > > > > > Mark > Depends on the size of your battery pack. It's not critical. For my > 3600 mAh nickel metal hydride packs I use a 75 ohm 15 watt sand > resistor. A bit small maybe? That's only 160ma. That's only 0.04C. It's also just under 2W, so your resister is way bigger than it needs to be. I'd pick a load closer to what a real ignitor load would be, which is why I like a 2.1A taillight bulb (should be about 6 ohms), which comes out to about 25W. Before I used the taillight for a test load, I had a bunch of large wound resistors. I made a load pack of 4-6 of them in parallel to both drop the overall resistance and increase the wattage. Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle: http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org 26-October, 2001: A day that will live in infamy Support Freedom: http://www.indefenseoffreedom.org/ ... One nation under survielence, divisive, with liberty and justice for none. |
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