Quote:
Originally Posted by rcheshire
I'm designing a utility bus to supply power to various components on my GEM. The bus is powered by a single lead from a PSU 12v 12.5amps, which is more than adequate.
The bus will be mounted on the mount with short leads to each service - mount power, camera, dew heater, logic (various stuff), LED lighting, power ON indication and a spare 12v outlet.
Not being an EE, and with very basic skills in this area, I'm stumped as to how to maintain 12v across all services (which I have tried to represent with various resistances depending on what I think maximum power demands will be - manufacturers specs and my own measurements).
I think I'm making a fundamental error/s. Having tried a few different configurations, the diagram below is the closest I can get to achieving 12v across all services.
An in-line master power switch (not shown here) reduces voltages significantly, which is not ideal.
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Your design will not necessarily have a constant voltage at the loads because your design is basically a current source not voltage source because of the resistance of the line from the PSU. However modern electronic devices of the types you envisage using will have wide primary voltage tolerance and any critical internal circuitry will be supplied by internal dedicated regulators and the voltage drop from the line resistance will be negligible.
A simple two wire bus with intermediate sockets will do what you want if your bus cable is capable of carrying the maximum required current without voltage drop. If your 12v supply is some distance from the equipment your could consider running extra wires to supply the regulator sensor at the end of the line rather than the beginning to ensure that there is 12 volts available at the load rather than the source.
We use a simple 12v 15Amp PSU that I built 25 years ago and an array of sockets to suit the specific equipment on the G11. The real need for distribution is the USB line form the computer to the various devices and that is done with a hub fastened to the mount with Velcro strips. The cabling to each device is then made to size and bound into a harness that feeds each device neatly.
Barry