Is this circuit fit for purpose if used on a 12vdc pump?

[cygnusv]

Three years ago KrisBlueNZ - RIP - kindly produced the following circuit for use on my 24 volt boat. The problem was back emf destroying contacts in the pumps pressure switch. This circuit completely solved the problem and 3 years later it is still in continuous use.

2 friends of mine are suffering exactly the same problem, but with 12 volt pumps. These pumps are rated at not more than 6 amps. Would this same circuit work on 12 volts or should components be upgraded?

Many thanks, Stu

 

[Alec_t]

The diode is rated for 15A continuous, so should be fine, even allowing for pump switch-on surges.

 

[kellys_eye]

The LOWER diagram is correct for polarity.

 

[duke37]

One diode is NV-1S3210 and the other is NV-1N3210R so they are of opposite polarity. The symbol we see may not be an indication of polarity and it looks as if the lower picture is a mirror image.

Did Kris reverse the image to show the physical connections?

 

[Cannonball]

If there is any doubt, check it with your service meter before installing it. The marking on the diode is the same in both schematics and I believe that is correct.

The diode in the top schematic is installed wrong.

 

[cygnusv]

I think Kris simply reversed the image, because I used the top image with the threaded end of the diode to the negative side of the circuit. Three years on it still works properly and it is still the original pump.
Is everyone happy that this will work with 12 volts rather than the 24 volts it was originally used for?

 

[Cannonball]

Yep!

 

[cygnusv]

Magic this forum. Many thanks all. Stu