I'm building a motor speed controller with a few added extras, the controller board will run from 5 volts to 30 volts, I will be using it 90% of the time for controlling 12 volts motors, I will need, on the odd occasion to control a 5 volt motor but the input will always be the same, 12 volts, question is would this work using a LM78S05

Thanks

 

Better to put the SPDT switch on the output of the regulator, with the regulator input permanently connected to the +12 V input. The other two switch connections are unchanged. This eliminates the diode so the 5 V load gets the whole 5 V instead of 4.3 V.

Also, read the datasheet for the regulator; it requires some capacitors (input/output.both?).

ak

 

Like this?

 

+ capacitors, yup.

ak