Phone Charger

[Korolija123]

I've seen a project recently about Bycicle Phone Charger. I've found schematics for it and the system uses 12V Dynamo Generator and I have one that generates 6V. In order for it to charge a phone it needs to be dropped to 5V. Here's the pic of the circuit

I know, I could use diodes but that will drop voltage to 4.6 V. I don't want to damage my system with too much power but still I don't know if this is going to charge my phone. The schematic up uses 7805 regulator I believe but 7805 regulator requires 7V in order to drop electricity. Is there any other solution or I just connect two diodes (Or only one?)?

 

[(*steve*)]

Beware that a dynamo can generate very high voltages if operated without a load. These will kill the 7805.

This will happen when the phone is disconnected or stops charging.

I'm not sure what the best protection is. Perhaps a 5W 20V zener across the output of the rectifier?

 

[davenn]

Steve

was that supposed to be 5W 20V ?


D

 

[Korolija123]

Beware that a dynamo can generate very high voltages if operated without a load. These will kill the 7805.

This will happen when the phone is disconnected or stops charging.

I'm not sure what the best protection is. Perhaps a 5W 20V zener across the output of the rectifier?

The circuit works fine for others... I think I've found a solution. Connect the car charger to dynamo through mechanism that is in the car. The car charger converts any voltage to 5V so, what do you think?