6 V DC to 4.5 V DC for bike lights (LED)?

Have a Shimano front wheel with hub dynamo. It generates 6 V DC, voltage regulated.

I want to convert some ready to use LED gadgets for illuminating the bike and the road during these dark days. Many of them use 3 button cells or AA(A) batteries.

A small circuit board in the head light (have a huge motorcycle front armature ready) must convert the voltage. When I look for a 'buck puck', it seems that this lowering step is too small for what's available. true or not???

sort by: active | newest | oldest
luxstar4 years ago

Here is an instructable using a DC to DC converter:




The data sheet says the input voltage can be 4.5 to 14 volts. The output can be adjusted from one half volt to 6 volts. Murata makes several different devices for different current / wattage requirements;




BobS (author) 7 years ago
The diodes I found in 2 dead CFL bulbs. I use 2 for the 4.6 V rail and another 3 for 2.5 V, to power a few yellow and green LEDs.  Ordered a 2.5V 25 F supercap for some lights to remain on for a while.  Fixture and switchbox are half finished, so probably next week, there will be an instructable!!
BobS (author) 7 years ago
Just got struck with the (swine???-) flue. But I have a dead CFL, in which I see 4 diodes. The coming days, in a slow pace, I'll desolder them, wire them up, and see what it will do. Sounds promising.....
Fresnel1107 years ago
 If you are just prototyping you can use one (normally one works well) or more small diodes--there is a voltage drop in between
 You can use the 6v directly to power the LEDs.  You may have to add a bit of resistance in series with the LED circuit.  Try 100 ohms.  If the LEDs are too dim, use a lower resistance, or put two 100 ohm resistors side-by-side, which gives you 50 ohms.

Check out the LED tutorial that has a LED calculator too at http://metku.net/index.html?sect=view&n=1&path=mods/ledcalc/index_eng