I found that 100 uH was a good all around value for these solar garden light circuits. But at the time I made these around 2009 the 5252 4 legged chip was uncommon and almost all the garden lights used 2 discrete transistors. I don’t know why they started using the 4 legged 5252 – it would have made more sense to use a 4 pin surface mount chip.

I bought a few dozen 100 uH 10% chokes from an online guy and I measured them at 75 to 80 uH with two different meters. I emailed the guy and I sent them back and he refunded the $$. He also measured them at too low a value with more than one meter, so he had no explanation for the out of tolerance issue. This isn’t the first time I’ve had this problem.

So I gave up on RF chokes for this circuit and started buying the Fair-Rite 594300(something) 3/8 inch or 9mm ferrite toroid cores for 12 cents apiece and winding a 8 inch or so piece of wire on them to make any value of choke that I need. They’re lower resistance so have less I squared R losses than an RF choke – every loss takes away from the brightness of the LEDs. I’m much more satisfied by the results. Every electronics tech or hobbyist should have a few dozen ferrite toroid cores in his parts stock to quickly wind a needed value of inductance. The cores can be from .25 inch or 6mm up to more than 1 inch or 25 mm but larger sizes get expensive. You can get them already wound, of course. A good source for small ones were the CFL lights.


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