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Looking 4 competent electronics engineer/hobbyist

Posted by nice cuppa tee - Created: 13 years ago
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I have a Makita 12v electric drill with rechargeable batteries which is a first rate bit of kit. Unfortunately the battery charger is broken. I've had a poke around inside and it is just the 240v transformer that is blown.  But as I'd like to use the drill on my boat, which has 12v DC system, this might be a blessing in disguise. I'd like to modify the charger to run off the boat electrics and so have no need of the transformer (and no, you can't just plug it direct into the 12v circuit of the boat...). Are there any electronics whizzos living locally who could help me modify the charge controller?




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Posted by jjoepage - 13 years ago

...yeah, this isn't too hard to do.  That 240v transformer has another voltage on the other side.  You might be able to find out its voltage by merely looking at the transformer for ratings/specs.  Then, go to www.mouser.com to find many very cheap transformers.  The one you'll need is a 12v/??v transformer; where ?? is the voltage on the low voltage side of the burned x4mer.  That should drive the rectifier on the charger just fine.  Mind the current though; a drill charger is likely to take an appreciable draw.  Size of the transformer is an indicator as to its current capacity.  Try to get a tranformer of similar size - or slightly larger - if you cannot determine the current on the low voltage side.  (You could measure this with and ammeter but you need a working transformer already which you don't have!  -  or a power supply of correct, or variable voltage).  Anyway, good luck on the project.