I want to add a light that comes on when you open the door to my tiny library that's powered by a small solar panel. I'm no electrical expert but I do know basics enough to make simple circuits.

My original idea was to cannibalize one of those cheap garden solar lights that come on when it's dark out and then run it through a normally open switch attached to the door. My problem is that the lights I want to use run off 12v and the output of the little circuit board is around 1.5. I tried running a voltage booster circuit off the output of where the LED from the garden light was, but for some reason it won't register anything on the output side of the booster.

Does anyone know an easy (and more importantly cheap) way to make this work?


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    \$\begingroup\$ The solar light you took apart is only producing a few mA at 3V like a joule thief. A step up boost circuit already. Trying to add a regulator to that and drawing a watt isn't going to work. You need a bigger driver. Plenty of circuit examples online. How much current do you need? \$\endgroup\$ – Passerby Sep 18 '20 at 2:33
  • \$\begingroup\$ Do you read books only during the day? \$\endgroup\$ – Indraneel Sep 18 '20 at 2:54
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    \$\begingroup\$ You will need a 12 volt battery and a much larger solar panel designed to charge a 12 volt battery. \$\endgroup\$ – Peter Bennett Sep 18 '20 at 2:56
  • \$\begingroup\$ I'm not sure how much current the lights draw, my whole idea behind this project is to not spend any money. I was hoping to get away with the lower volt charger and not a 12v system because the lights won't be continuously on, only maybe 30 seconds per night \$\endgroup\$ – user168694 Sep 18 '20 at 6:10
  • \$\begingroup\$ If you look at the datasheet for the booster I think you will find your challenge (1.5 volt) \$\endgroup\$ – Mats Karlsson Sep 18 '20 at 9:15

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