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need automatic switchover between two dc power supplies of 12vdc and 30vdc for the same load.ie dc fan.

before i ask i must say that i am not a student dont have any school educational background but i do love to play around with electronic devices every now and then so i be direct if there is any expert in electronics i am tryin to built a circuit diagram which is actually an automatic switch over between two dc voltage supplies of 12volts and 30 volts for the same load.actually i want to run a dc fan first with 12 volt dc and after some time i want this 12 volts to be completely turned off and automaticaly starts running of off the secondary 30 volt dc and will run continuously then unless switched off manually

crapflinger3 years ago

I am by no means an expert, but I would assume that it would be easier to actually use a variable power supply that's capable of 30v (at least) and can be tuned down to 12 volts. these are things that exist in the industrial world.

what's the purpose of the voltage change to begin with...changing the speed of the fan?

justakidlikeu (author)  crapflinger3 years ago

thanks for the reply i don't want to tune down the speed its just that i want two different actions from one load using two different voltage sources i may have mentioned a fan but its not a fan in real.