bicycle dynamo battery recharger

[dhabell]

I am interested in making a cheap easy to build, bicycle generator battery recharger system. I need it to power an old fashioned boombox cassetteplayer. I plan on using a wheel dragger generator. I would like the generator to be able to charge the batteries while the batteries are powering the boombox. Can you please help me with the parts Ill need? or does anyone know where I can just buy one? thank you in advance for your consideration.

 

[Lynx_Arc]

I think before anyone can help you they will at least need to know a few things: what voltage (how many batteries) does the boombox use and what is the minimum voltage the box will operate at. Another thing needed would be imformation about the generator you are considering as the source of power also, that will help determine the design. It sounds like a fun project but I have an old circa 1976 cassette boombox and it can run a long time off batteries so IMO if this isn't just a fun project it may just be easier to charge batteries at home and run them in the box instead as you may be able to run the box several days off of a set a rechargeables. My boombox uses 6 D cells but runs fine off a 6v lead acid battery as I use it during power outages that way but at low volume levels it ran for over 4 days off a 6v 4Ahr SLA

 

[Magic Matt]

I have my MP3 player running off of my bike. I used a dynamo from a set of bike lights, and I have a simple CMOS PIC chip running from a single AA cell to control the switching of the circuit. If the voltage from the dynamo gets above around 4V (I just use the TTL input on the chip) it switches on the circuit to the MP3, and there's an in-line 5V regulator to stop it pushing too to the player. The player itself automatically charges while playing if you plug it in, so that handles the battery charging etc. automatically while I pedal, and doesn't stop if I have to break. I'm using a solid state relay to open and close the charging circuit.

Does that help at all?

 

[dhabell]

thanks guys that helps a lot. on second thought I guess it would be way easier to just recharge the batteries at home. at least until I check out a book at the library on electronic circuits...

maybe Ill just try to build a cheap and easy cree light first... any suggestions?

 

[Magic Matt]

Depending on how new you are to it all, I'd start by making a multi-LED circuit out of 5mm white LEDs. Most people here hate them, but at the end of the day if you fry a few 5mm LEDs it's no big deadl - frying Cree LEDs is a bit expensive. Once you've got that licked, then learn about heat sinking etc. and go for it (that's the stage I am with the lighting).

I came at this the wrong way really... I know all about PIC programming and can build computer software systems and relay circuits, but working out current and voltage for LEDs had me stumped! LOL!