From: Skenny@highstream.invalid   
      
   sbudz wrote:   
   > I have electrical and electronics from my days in the navy 62-66. so I   
   > know something about this, but not much.   
   >   
   > I want to build a 'box' that will allow me to connect my solar panel   
   > (12-18v) and also a ac/dc adapter 12v to my low voltage solar power   
   > pump that I use in my backyard fountain.   
   >   
   > right now the solar panel doesnt work in the shade or cloudy days. so   
   > at times I use the 12 volt ac/dc adapter.   
   >   
   > what I want to build is a device that will allow me to connect both   
   > the solar panel and ac/dc adapter to it, and be able to use the unit   
   > (solar panel or ac/dc adapter) to the pump,   
   > and send the low voltage to a resistor or whatever.   
   >   
   > right now I have disconnect wires every time I want to use the other   
   > device.   
   >   
   Wouldnt a relay do this?   
   Have the solar panel turn on a relay at a certain voltage, then have the   
   relay disconnect the pump from the solar panel and connect to the adapter.   
   You could use a transitor switched by a zener diode when the solar volts   
   reaches 12, then turn off at below 12. The transistor would turn on the   
   relay.   
   Or to save solar power, have the relay powered by the ac/dc adapter, but   
   the relay controlled with the transistor, by the solar panel.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)