This site shows the coil they are using. Lots of turns of small gauge wire. The gauge is not important but the number of turns is.
https://www.sciencebuddies.org/science-fair-projects/project-ideas/Phys_p097/physics/high-speed-magnets-faradays-law-lenzs-law From: Mark Radabaugh Sent: Sunday, November 3, 2019 8:20 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] OT: Induction coil voltage An old motor or speaker will have a decent amount of enameled wire it it that you can use. Scrape or melt the enamel off where you want it to conduct. Use two LED’s in parallel with the anode opposite directions and you should get alternating lights when you shake it. I wouldn’t worry about the meter - if it’s digital it will be too slow to show you much. Mark On Nov 3, 2019, at 2:54 PM, ch...@wbmfg.com wrote: The magnetic field from an electromagnetic is proportional to the turns and the current. So the inverse is also true. You have a fixed amount of magnetic flux, the current will be proportional to the number of turns. It is called the ampere-turns ratio. Lots of turns of 30 gauge will be good. 30 gauge is common as it used to be used for wire wrapping. Also make sure the magnet is oriented such that its field cuts the coils at right angles. I would not worry so much about the voltage. You want 10 mA if you can get it. https://en.wikipedia.org/wiki/Ampere-turn From: Adam Moffett Sent: Sunday, November 3, 2019 5:51 PM To: af@af.afmug.com Subject: Re: [AFMUG] OT: Induction coil voltage I'd bet I have 20-30 turns of 16ga wire....that's just what I happened to find first. I could tear apart some CAT5 and use the 24ga inside so I can get more turns in the same area. Or I can find something with a transformer inside and unwind the super skinny wire on it. I just don't know to what extent I need to go to make this thing work. And yeah it's not obvious in the picture I sent, but you're supposed to connect the two LED's together short leg to long leg so that one of them lights up when you drop the magnet North first and the other lights up when you drop it South first. I'd wondered about the length of the pulse too. It's a cheapo digital multimeter. It does not read the same on each drop of the magnet. When I say it read 30mV that's just the highest number I saw after several drops. -Adam On 11/3/2019 12:40 PM, Ken Hohhof wrote: I would think yes, although it seems the electrical pulse will be very brief and I’m not sure you’ll be able to measure it with a meter. Also have you determined the polarity of the DC generated or tried hooking up the LEDs both directions? In any case, I’d think wrapping the entire length of the cardboard tube with wire would make the LEDs light up for a longer time and be more visible. How many turns do you have on it now? From: AF mailto:af-boun...@af.afmug.com On Behalf Of Adam Moffett Sent: Sunday, November 3, 2019 11:20 AM To: af@af.afmug.com Subject: [AFMUG] OT: Induction coil voltage I wanted to do this science experiment with the kids. My problem is my LED's don't light up. It's from a discontinued textbook. Apparently they sold a kit with the materials for all the projects, but that's no longer available so I'm scrounging in the garage. I put a volt meter on the rig and I was only getting 6mV when I dropped the magnet. I doubled the number of coils on the tube and then doubled the number of neodymium magnets and I'm getting closer to 30mV now, but I need closer to 2V to light up an LED, so I'm wondering what would increase the voltage by two orders of magnitude. Is it based on the number of turns in the coil? <image001.png> ------------------------------------------------------------------------------ -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -------------------------------------------------------------------------------- -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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