I am a cyclist and electronics hobbyist, so I am designing an electrical system for my bicycles.
THE QUESTION
"What do I need to know (standards, available components, good practices) so that I can design the proper CONNECTIONS in the system, either the cables leaving the circuit boards, or the external cable connections between components?"
I will use one hub generator on each bike. It produces alternated current at nominal 6V / 3W, this is sort of standard.
My plan is to have an "electrical system" on each bike, whose central unit would be a regulator/rectifier/limiter. This regulator would take the power from the dynamo and provide 6V DC to every other pluggable device in the system.
My concern is that I don't know what electrical and mechanical characteristics are commercially available in order to make connections that are:
- Weather resistant;
- Mechanically resistant to shock and vibration;
- Easily pluggable/unpluggable;
- Easily serviceable (disassembling for cleaning and/or substitution of modules);
- NOT over-engineered…
Hopefully, I will replace what I have now, which by the way works fine, but leaves a WHOLE lot of room for improvement… (image)
Best Answer
The AC output voltage of your generator(s) varies under a constant resistive load (see http://www.seeedstudio.com/wiki/Bicycle_Dynamo_With_Bracket_-_6V_3W#Specification). What are you planning to power with your "electrical system"? Traditionally one would be powering incandescent lamps, which don't care whether they receive AC or DC or at what voltage (when you slow down, the lamps dim). The more sophisticated the load, the more voltage regulation you will need. Rectifying AC into DC requires a simple diode bridge. Then, you would obtain regulated DC by using a voltage regulator (for example LM7806 if you want 6VDC). Surround the 7806 with appropriate capacitors, see the data sheet. Note that you can't get regulated 6VDC from rectified 6VAC -- the 7806 requires at least 8 VDC of input to get 6 VDC output. You might also want to use a largish capacitor or two to keep the DC voltage constant for brief intervals while you are slowed or stopped in traffic. If you are trying to power a device such as an Arduino or cell phone, you are probably better off charging a battery and running the device from the battery.
As far as connectors, I would use Molex connectors, one wire at a time (toss the nylon shell), use heat shrink tubing (as you are already doing) on the individual wires and also on pairs/bundles of wires. Hopefully you won't be disassembling your wire harness all that often, and this arrangement should provide adequate protection against strain, moisture, and vibration. (In moist environments put a dab of silicone sealer under the heat shrink tubing with a toothpick.) For servicing, just slice open the heat-shrink tubing and unplug the Molex connectors.