I asked a question the other day but am still unsure, I just bought a 0-30v 0-5A dc regulated power supply today and want to use it to play around with various DC motors, I was told I didn't need to worry about a fly back diode with a straight motor one the other question but the store I bought it from still recommended and sold me a 10A07 diode, the data sheet is in this link http://pdf.datasheetcatalog.com/datasheet/mcc/10A07.pdf
My question is, is it really needed?, the guy at the store said its just safer to use one so i figured why not. After looking at the data sheet it seems it can handle up to 1000V reverse voltage so im assuming its good.
The power supply is only a cheap $150 AUD one so im not to sure if it would have the proper protection but I have read that fly back diodes are mainly used with transistors, Is that true and did I get sold something I don't really need or would it still pay to use it anyway? Im completely new to electronics so any help would be appreciated.
Thanks in advance
Best Answer
The motor can be supplied up to 5 amps so all you need is a diode that can handle a peak of 5 amps (not continuous) and has a reverse working voltage that is at least 40 volts (a bit more than 30 volts).
A 10 A continuous diode capable of a reverse voltage of 1000 volts is of course perfectly usable but i question why a 1N400x wasn't recommended: -
It can stand-off 50 volts and handle a peak of 30 amps and probably cost a fraction of what you paid for the heavy duty diode (that can handle up to 600 amps of peak current).
Yes, I would still fit a reverse diode.