The first six 18" cars I put LED lighting strips in I used 317s. I didn't have PC boards but used vector board instead. One car I cut the traces every 3 leds and reconnected the 3 led sets is parallel. This allowed the lights to come on at 3 volts for conventional running.
I just picked up some buck boost modules. They measure about 1/2" x 3/4". Just add a bridge as shown above and a cap to smooth the ripple. Total cost about $1.25 and I don't have to have PC boards built.
Just plugged them into a 16" strip, about the size that would work in an 18" car and adjusted the DC voltage and the lights lit at 8.5 VDC. 12 VAC at the transformer. I ran it for about 30 minutes and it barely got above room temperature.
If I could purchase that 317 above on a circuit board for the same price I would consider it. I agree 317s are very versitile but at the moment can't match the price or ease of use.
Cap was what I had on hand to test the circuit but smaller ones will be ordered.
Pete
