motor as a generator question

Discussion in 'Start here' started by toozie21, Jan 6, 2018.

  1. Howdy. I know this is off-topic, but I hope that is OK for this forum (feel free to remove if not). I stumbled onto yourall's great sight while doing some research on motors as generators.

    I have a similar application to you guys, but on a MUCH smaller scale. What I am looking to do is create a "tower of power" Christmas display for my yard for 2018 (I like to have a homemade mechanical Christmas display). My vision is of a wooden cut-out of a Christmas tree with some staggered 12V bulbs going up it. I then was going to use bicycle parts to create a hand-crank that drives a generator/dynamo. As the user cranks harder, I want more and more lights to light up (think the ringing-bell sledgehammer prop at fairs).

    I am a digital electronics guy, so my power background is pretty limited. Based on my research on this and other sites, I think I know what I need, but I am having trouble finding something that fits the bill that doesn't cost a fortune (since this is a prop that is going to sit in a yard for a month out of the year and subject to weather/kid's abuse). I should only need low wattage since I just want to power a couple of bulbs (not sure if I am doing 12V light bulbs or maybe LED C7 sized Christmas bulbs), maybe something on the order of 50W - 100W total power budget.

    I was hoping someone could maybe guide me in the right direction (I still am not 100% sure why a motor generator is preferred over a dynamo, whose purpose I thought was to do this sort of thing....). Correct me if I am wrong, but I am thinking I need a 12V permanent magnet DC motor (why not a dynamo?). Then I need to make sure it can supply somewhere on the order of 4A - 8A (to get me my 50W to 100W range). Lastly, I think it needs to supply the 12V at a low RPM, say ~100RPM since this is going to be a hand-crank operation. Does this sound like the requirements for this sort of project?

    If I am on the right track, can someone point me in the right direction of a motor that can handle this? I either find things that are rated for very high wattage (like what you guys need for your wind generators (and would be overkill for this application), or it is stuff in the $100+ range, which is where I didn't want to get into. I don't mind using used/reclaimed motors if that helps drive the cost down, I am just not sure where to go from here (been spending most of my time looking for motors on Amazon and eBay and some on random Google searches).

    Thanks again folks and have a good weekend!

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