Proper diode for small motor

Using Arduino Motors, Mechanics, Power and CNC
1

Hi, I'm trying to run a 21v 1.2a dc motor (from a hot air popper). Here is a photo of the connectors. Note that the connectors to the motor are at the top and bottom -- the left and right sized are not touching the motor -- just the place where the wires and diodes come together.

There are 4 diodes connected to the terminals. Is this sufficient for preventing kickback?

Thanks a lot

2

Yes. That's a bridge that allows the motor to run from AC and if you chop the supply voltage, the motor's inductive current will be pulled through the diode bridge, ie it will operate in slow-decay mode.

The motor will not be reversible with that bridge on there.

Edit: it's OK as long as you use the red and white wires provided, and don't directly connect to the motor terminals. Making such a direct connection and getting the polarity wrong will mean shorting your supply through the diodes.

3

As already pointed out, the diodes in the photo are not flyback diodes, they are part of a full wave bridge. They are however, exactly the same kind of diodes that would be used as flyback diodes and the full wave bridge configuration provides the same protection
as a standard flyback diode .
Try this: :
Draw a schematic of the a motor with a fliyback diode across it. (like below)

motor ^ <== (flyback diode)
|

Now draw a schematic of your motor as it is appears in your photo and rotate it 90 degrees in the clockwise direction and compare it to the schematic of the motor with the flyback diode. You'll see the similarity with the exception that to you it
will look like a motor with two flyback diodes in series wired in parallel with another similarly wired pair of diodes, yet while
the function of two circuits is totally different, (one if provideing back EMF protechtion,the other is rectifying ac ) you will
see that the bridge rectifier diodes provide flyback like protection. The are the same rating, same polarity (with respect to the back EMF) so actually they are providing a dual function.

^ ^ <== (bridge rectifier diode)
| motor |

^ ^ <== (bridge rectifier flyback diode)
| |

BRIDGE RECTIFIER-2.jpg