Input voltage on 32212 Proto Board

MSDTech

I know the documentation states the input is 6-9VDC, but I would like to use a 12VDC input. The specification for the LM 1086-5.0 states that it has an input max voltage of 25V. The total power draw will only be needed to power the propeller, all other circuits will be running of a separate 5V supply. Is there any problem with using the 12V supply.

tomcrawford

As you already know, the problem is getting the heat out of the regulator. 12V is gonna result in more voltage across it; more power. I would use the rule of thumb: if you can keep your thumb on it, it is not too hot.

Mike Green

There's a 10uF input capacitor on the LM1086-5.0 and the Proto Board schematic doesn't give the voltage rating of that capacitor ... it's probably 16V. The usual reason for not using more than 9V would be heat dissipation. Just powering the Propeller would not cause a problem there. Still, it would be better to use a cheap LM7806 on the input to the Proto Board. This doesn't require an input capacitor unless it's not close to the power source (then 0.33uF will do ... rated for 16V or higher) and the 10uF capacitor on the Proto Board will be more than adequate for output stabilization.