Contactless dynamo powering bike safety lights

Step 6 The circuit

The following circuit shows a way of powering 5 bright leds with two coils that are not generating energy simultaneously. If you just connect them in series, one will absorb part of the other's energy. This does not happens here.

I have not used any capacitor since I wanted to have all leds blinking a lot! Anyway the only place you could really place one is in parallel with led3 since it never gets negative voltage. So you will have one steady led and the other 4 blinking...

It seems that the coils' resistances should be kept around 100 or200 ohms but I used two 600 ohms coil and it worked fine.

Comments

[loccci]

hi, i dont understand where to put the capacitor if i want one led or more to stay on constant. do you have to charge the capacitor intitially. why is the only place you could put it parallel with led3? why does it not get negative voltage? why arent all of the leds in parallel? led2 and led4 seem to be in series, why is this? sorry i just dont get it. thanks

[scraptopower]

I don't think it is possible to add capacitor smoothing to this circuit without adding a bridge rectifier (use schottky diodes for efficiency).

He has wired the circuit in that way because the waveform is not mirrored, so there's less load when the coil - wire is more positive. At least, that's what I think,,,

[rpvanpatt]

 ..i'm new to all this so dont mind the question... could it be possible to put a capacitor in front of all the leds?  and maybe with a switch, so that you could turn them all on and off with out any blinking?  thanks

[The Insignificant User]

http://www.instructables.com/id/Contactless-dynamo-bike-wheel-lights/
It's by the same author as this instructable. The circuit diagram is similar enough to what is happening here for you to get some idea as to what's going on. If you need a place to get capacitors/LED's, try Jameco.com. It's a pretty good site if you want low prices and fast delivery.