The trick will be in designing your heating element. For a 30ga nichrome wire, expect load currents in the range of 500mA - 1A over the length of your sealer at ~1-1.5V per inch, your power demands will go up rapidly as you increase the wire thickness.The nice thing is that since you're only using it as a low duty cycle device, the actual power required won't be nearly as bad as what would be needed if it was continuous duty. Don't expect to get away with using a 9V battery though. Yes, they can be used to heat a nichrome wire, but they will drain far too quickly to make them an effective source. Consider AA or C cells (at least)There will be some experimentation required to determine the correct "on duration, so I hope you have a bunch of bag material to use while developing. (also, use different bag thicknesses and record EVERYTHING you do and all the settings used, so you have basis for setting the gizmo for various target bags later on)
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I've already got one. It's very nice. ;-) Well, it's alright. Probably nothing to write home about. The SealTite(tm) ST-10 is powered by two AA batteries, and it is designed for sealing plastic bags. I found mine years ago, in the same aisle as the potato chips. The actual heating element is very small, with a length of only about 5mm. To seal a plastic bag, it is necessary to draw the sealer across the line you want to seal, and that sort of works. If the seal you draw has gaps in it, it is possible to go back over just that part. The final result is a good seal, even if it doesn't look pretty. In contrast, the usual trick for heat sealing a plastic bag uses a heating element whose length is greater than the width of the plastic bag. The whole wire, which is maybe 20 to 30 cm in length, heats up, and it seals the whole length in one shot, er, um, impulse. I got the stock picture for this gizmo from here:http://www.google.com/products/catalog?q=sealtite+bag+sealer&hl=en&tbm=shop&cid=13615079270868933678 Some additional details regarding this device's construction may be gleaned from these US Patent numbers, I found printed on the device itself: 5142123, 5854468, 6064038http://www.freepatentsonline.com/result.html?query_txt=5142123http://www.freepatentsonline.com/result.html?query_txt=5854468http://www.freepatentsonline.com/result.html?query_txt=6064038
If you mean "plastic bag heat sealer", the answer is a definite yes. Check out "heat sealer" on eBay and you'll find them; they're quite inexpensive. To build one you'll need a resistance wire that, when batteries are connected, heats but doesn't burn through. That's going to take some trial and error. You'll also need some silicone or teflon-coated paper/plastic on the resistance wire so that the softened plastic won't stick to it. Resistance wire requires a fairly high current. Be aware that batteries will disappear rapidly when used in a heat sealer. Good luck.
I have been needing to seal up mu impulses for years!!What exactly do you need this for - I at least am not familiar with the terminology.