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  • JesperE2 commented on omarreis's instructable The Foamboard Octant3 months ago
    The Foamboard Octant

    Wow, that's probably the simplest way I've seen of making a working navigational instrument. Brilliant! I like the lego, especially as a holder for shades.About the shades though: not all welding masks protects properly from the type of UV-radiation that's the most damaging one from the sun. Older masks and goggles are more likely to be sufficient, since they are more broadband dark, but newer ones are more selectively dark so that they can be more protective in the wavelengths that a welder is more likely to encounter. Please be careful to check wich wavelengths your shades protect against and to which degree, and perhaps ask a supplier of hobby astronomy stuff or something if it's good enough for the purpose. (sorry if I'm incoherent, English isn't my first language)

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  • Beeswax Wrap - Reusable Substitution for Plastic Wrap

    That's interesting! Just collect some resin from a "bleeding" pine and then what, grating it together with the wax? How much should I use? Does it get sticky, stiffer, or more malleable?

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  • JesperE2 commented on bekathwia's instructable Solar Engraving1 year ago
    Solar Engraving

    Brilliant! I'll try this in a couple of months (not much energy in the few beams of sunshine we get in northern Sweden during winter) if I can remember to do so when summer comes. Perhaps I'll try to incorporate some kind of support for the magnifier so it's easier to harness the meager rays we do get in spring.

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  • DIY - Holographic Parabolic Mirrors - the Mirascope

    I must confess I don't get what you mean about the correct identification of the parabola, but if you check wikipedia or wolfram alpha you can see more about how parabolas work. Edson1974 provided the most important bit of information - the focal length should be twice its thickness so that the lower mirror project the image through the hole in the upper mirror. This means that the relative curvature is set - it need to provide the focal length. So if you wish to "fatten it up" you also need to make it proportionately wider, otherwise the projection will fall short.

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  • JesperE2 commented on wold630's instructable 3 Simple STEM Boats1 year ago
    3 Simple STEM Boats

    Cool projects! I'll definitely try at least the first and the last. But shouldn't the put-put-boat be more efficient (yeah, I know - it's not primarily efficiency that appeals, but still...) if it sucks water from the bow and expels it in the stern? Or would it be to difficult to get it balanced enough to go straight? I suppose adding a keel or another tube would be somewhat over the top...

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  • JesperE2 commented on thediylife's instructable DIY Cordless Cold Heat Soldering Iron2 years ago
    DIY Cordless Cold Heat Soldering Iron

    Well, actually the author stated in the fist part of step 7 that "Don't attempt to solder any sensitive electronic circuitry with this soldering iron. There is a voltage difference across the tip which may damage sensitive components."so you're probably right to be cautious.However I wonder how sensitive the components need to be in order for them to be damaged? It should be a voltage divider between the other side of the tip and the components other side (if it's at all connected to the other side), which should make most of the current to favour the path through the tip rather than the component. (I apologize if I'm unclear; English isn't my first language.) With a maximum starting point of just over 5V and 5A there shouldn't be much that goes through the component. And sinc...

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    Well, actually the author stated in the fist part of step 7 that "Don't attempt to solder any sensitive electronic circuitry with this soldering iron. There is a voltage difference across the tip which may damage sensitive components."so you're probably right to be cautious.However I wonder how sensitive the components need to be in order for them to be damaged? It should be a voltage divider between the other side of the tip and the components other side (if it's at all connected to the other side), which should make most of the current to favour the path through the tip rather than the component. (I apologize if I'm unclear; English isn't my first language.) With a maximum starting point of just over 5V and 5A there shouldn't be much that goes through the component. And since it's battery powered it is virtually ripple free DC that is rather benign to most components. Any ideas on that?I suppose that the only way to really know is to test on a couple of components that you can afford to loose, and if I build this or anything similar I'll make sure to do that. I've got a substantial pile of electronic scrap that my wife wouldn't mind if I reduced somewhat...

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  • JesperE2 commented on thediylife's instructable DIY Cordless Cold Heat Soldering Iron2 years ago
    DIY Cordless Cold Heat Soldering Iron

    I agree, it does look like a cold joint. I don't think that should be inherent to this design though, but rather a matter of practice with the equipment. If the tip where to touch the leads and/or other points to be soldered as well as the tin then they should heat up as well. It should also be possible - with some training - to heat the leads or whatever is being soldered with the molten tin if that is preferable to avoid overheating sensitive items. If you follow the link the authors provided as credited for giving them the idea you will see that it is possible (although that particular iron isn't battery powered the tip and science is the same).If the size isn't deterring then there are 6 V MC batteries (found some just over 15x5x10 cm / 6x2x4 "), although I believe most are 12 ...

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    I agree, it does look like a cold joint. I don't think that should be inherent to this design though, but rather a matter of practice with the equipment. If the tip where to touch the leads and/or other points to be soldered as well as the tin then they should heat up as well. It should also be possible - with some training - to heat the leads or whatever is being soldered with the molten tin if that is preferable to avoid overheating sensitive items. If you follow the link the authors provided as credited for giving them the idea you will see that it is possible (although that particular iron isn't battery powered the tip and science is the same).If the size isn't deterring then there are 6 V MC batteries (found some just over 15x5x10 cm / 6x2x4 "), although I believe most are 12 V. The 6 V should be pretty perfect for this, and could be found for equivalently a couple of tens of dollars (at least in Europe - I'm from Sweden). That would also make the iron a lot easier to hold - it could be pen sized (albeit with a power cord sticking out the end).

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