Diode Warning Light

I did find one that is close at Radio Shack, part #276-114. It says; 1000V, forward voltage drop 1V, Forward current 2.5V, Max surge 80A.

Will this work in place of the 1N5408? Only a half amp differance.

The 1N5408 is available on the internet but you have to buy several and then by the time you add the shipping charges it gets to be over 30 dollars for a 50 cent part.

I looked for a warning light too at Radio Shack but they dont have that either. Went to the car parts place and they have warning lights but there isnt any watt listing on the packages or any numbers that match any of the bulb numbers that I have seen listed here. They didnt think any of the lights could be wired inline and then grounded to the frame so I just gave up.

Well, Its a small town and theres only one car parts place and one Alt place. The guys at the Alt shop are Mexican and I dont think they would understand any of this.

I guess this is why lots of people just go with the one wire setup.

Got one more place to check but this is getting kind of like looking for a needle in a hay stack.

The resistor gets a bit HOT if the key accidently gets left on, and the battery gets run down though the resistor.

If anyone needs one of the 1N5408's, I have them. I'd drop one in the mail to anywhere in the US for a SASE, and an extra $.39 stamp.

email, if interested.

bigcoulee@hotmail.com

P.S....

An "idiot light" with and LED in it will NOT work in the alternator's "excite" circuit, 'cause the LED doesn't draw enough current to "excite" the alternator.

You COULD, however, put a 10 Ohm 10 Watt resistor ACROSS the LED pilot light, and it would work.

I picked up the ones that Old mentioned at another Radio Shack in another town because I had to go to the Case dealer there anyway to get a seal. I think I got the market cornered on Diodes here in Texas now. The ones Old talked about (Radio Shack #276-1611) are sure a lot heaftier than the other ones I had gotten (Radio Shack #276-1114). I think I'll use the #276-1661 now.

Now I just got one question:

Can you put the Diode closer to the ignition swith, inside the instrument panel, where it will be hidden and out of the weather or do you need to get it as close to the Alternator as you can?

Post back when you get it "fired up", and let us know how it works. Sometimes, I feel like I'm "beating a dead horse" with this diode hookup, which is a REALLY SIMPLE way to convert to a Delco alternator, and works GREAT!

Will do. Working on the seal for the seed drive tomorrow first then.....?

I have to get the internal resistor changed back on Monday and have that diode trio checked. I'll start tomorrow but not before I sit it outside and show "baby" off a little.

Spring is comming and I got about another week to work on this and then its on hold until after the busy season.

Thanks guys. Yall been lots of help.

The diode is a simple and easy way to prevent the output of the alternator's diode trio from backfeeding into the igntion system, and possibly the battery, through the internal voltage regulator. The diode I use is a simple and "out ot sight" method to provide the same protection. I DIDN'T invent the diode trick. Some ag and industrial equipment has been set up the same way from the factory since "way back when".

Or a diode will work also if thats what you want.

Now a "Warning Light" is a different animal, its NOT a diode unless its some sort of LED, its a Light Bulb (an idiot light) which glows if shes not charging but goes off if she is and it can still serve as the same function of exciting the alternator and providing current limiting protection. It wires the same again between the ignition switch or coil and the alternators lil side No 1 (R) terminal.

Use a resistor (my choice) or a diode or an idiot light, your tractor your call.

John T

• Hobby farm

OK I found the 276-1661 online at Radio Shack (6A, 50V) and they still show they have that one.

Ill give them a call and get one ordered and forget the light.

• Radio Shack 276-1661

• Hobby farm

I picked up a simple panel mount red LED at Advance Auto Parts, stuck it in the electrical box in place of the fuse holder. Cost $5.48. Works fine.

Really, getting the exact part is not all that critical. Just get something close and you'll be fine.

It doesnt need to be grounded? Can you just let the light hang without touching the tractor frame? When I read on the conversation Bob talked about mounting it so I figured thats where it got its ground.

They had some what I would call "pin" lights that I wouldnt mind drilling a hole for and installing it in the dash if I knew for sure they would work.

So where does it get a ground from? I know I ask a lot of questions but I really want to make sure I do this right.

When the switch is turned off, the resistance of the lamp is enough to keep the back feed amperage below the level needed to run the ignition system.

In this set up the lamp must be good to provide the necessary voltage to the I terminal to excite the alternator. If the bulb fails, the alternator will not start charging. Usually there is a small resister across the lamp terminals to allow the alternator to begin charging even if the bulb fails. This resister also causes the lamp to glow less brightly than it would if it were directly grounded.

Ideally the control circuit (terminal A) should be connected as close to the battery as possible, normally at the battery cable on the solenoid or starter switch. That allows the alternator output voltage to be higher than the voltage that actually reached the battery to compensate for voltage losses between the alternator and the battery. The electrical load on these old conversions is so low that the control circuit can be connected to the alternator output terminal with no ill effect.

You explained that quite well. I think I got the jest of it.

Thanks

• Hobby farm