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ISO Electronics Guru

FuzzyDunlop

FuzzyDunlop

Diamond Member
I have a small hamster on a wheel toy that I received as a joke gift. I want to wire it to run in my car when I turn the key on.
I know I can easily make that happen with a simple relay, but what I dont know how to do is to bring 12V power down to what this hamster needs without frying it.

It runs off of two AAA battery's.
Do i just need a big resistor make it happen, or is there more to it than that?

Edit:got it working. Thanks for help.. I should also mention that I did see the hamster in another car, that's where I got the idea, but modding it to run on car power is my idea.
 
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I'm not an electronics guru, but this seems like a job for a cheapo ebay DC-DC converter (aka buck/boost converter). Seeing as the toy runs off of two batteries it should be running on very low current so the buck/boost converter should have no trouble in this application.
 
So theoretically, I could take that power converter and just run it right off the battery, because the cigarette plug gets power straight from the battery, doesnt it? Does the cigarette plug put out the full 12v?

EDIT: if thats so, this is easier then anticipated.
 
FuzzyDunlop said:
So theoretically, I could take that power converter and just run it right off the battery, because the cigarette plug gets power straight from the battery, doesnt it? Does the cigarette plug put out the full 12v?

EDIT: if thats so, this is easier then anticipated.
Click to expand...

Not in all vehicles, Dodge and Ford had them in older models not sure if that's still the case. Nowadays it will turn on only when you start the car, that's too its not a direct connection iirc. But yes, its much simpler that you are thought.
 
I have a relay that ill hook it up to so that it only runs when I have the key on. Just bought an adapter, heading home to tear it apart and make it work.
 
Not really an electronics guru but I think a DC-DC buck converter is what you want. You can use a linear converter which would be simpler but it would be wasting a LOT of energy that has to be dissipated so the IC does not fry as you need to go from 13v or so down to 3v so it has to dissapate 9-10 volts.

Given this thing does not use much power though you may even get away with a premade/packaged buck converter, like this: (just a random one I found, may want to do more research)

http://www.digikey.ca/product-detail/en/LM2576T-3.3/NOPB/LM2576T-3.3NS/NOPB-ND/363657

There may be some where you don't need to add an inductor and stuff too.

Actually these look interesting too:

http://www.digikey.ca/product-detail/en/ROF-78E5.0-0.5SMD-R/945-1690-1-ND/3593416 (5v, for that extra hamster power!)
 
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Red Squirrel said:
Oh I missed this post, I see it's working. That's hilarious! I'm sure it will be a good source of entertainment when you bring your car for an oil change. 😀
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haha, unfortunately only I change my oil on this thing. Many shops wont even touch it because they dont understand it (mid-engine wonkiness). Its a fun gag for friends and car shows though.
 
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