RE: doghead starter relay modifcation

[edpdx]

RE: doghead starter relay modifcation

I got the new relay for this project to stave off any backroad breakdowns. As I reviewed the procedure I see something that may be a problem- not in the original procedure; but in the "add-ons", if you will, with the added diode:

The original photos show the Black 12v Neg on the "left" (towers at the bottom) and the purple with stripe on the right side. In the postings showing the added relay the band of the diode shows an orientation toward the 12Vneg Black post; but in a folow-up question regarding orientation of said band the poster says it should be toward the purple wire with the stripe. I know it makes a difference, I just don't know what is correct

Now I realize that the originator of this procedure says that the diode is not essential; but if it does no harm, I am inclined to put it in- just as the relay for the horn has a diode to counter-act the surge when power is cut.

Any electricians know the correct orientation if using this diode?

 

[BIG_RED]

Band goes towards the positive lead. (one connected to power). Other end goes to ground.

 

[Speddmon]

Here is a little sketch of a typical diode on top and the electrical symbol on the bottom.

Power always flows from the anode to the cathode. I don't know what the situation is that you are using this for or the circuit it's in, but if you have a 12 positive hooked up to the anode, power will flow through the diode. If you have it reversed and a negative hooked up to the anode, power will NOT flow.

 

[doghead]

Post # 2 is correct for this application.

Arc suppression, the diode is in parallel with the relay coil, with the cathode(band) toward the positive voltage terminal.

 

[Speddmon]

If you are using it for arc suppression, then you really should be using an MOV (Metal Oxide Varistor). A diode is a crude way to get it done, but an MOV is made for that kind of application. Typically you'll see them paralleled with a relay coil or paralleled with relay contacts (especially in DC circuits) to minimize the arcing of the contacts that occurs over time due to the tremendous arcing potential of DC current.

 

[doghead]

As I said before, I don't think this is needed in this application. I do NOT recommend this.

This is just confusing others and gonna turn into a nightmare.

I think your mistaken on the MOV for DC relay(coil) use. (but I don't care!)

This is like applying rocket science to the Flinstonemobile.

 

[rnd-motorsports]