Can't find a diode for my TO30

[FergFan]

While rewiring my TO30 Z129...I've had an extremely difficult time locating a new diode for the wire going to my lights. I've been to four automotive stores and radio shack to no avail. Old one is operational but rest of the line is very old. I didn't recognize this line had a diode when I removed it, but I put two and two together when I attached the pos battery cable and things got a lil sparky

 

[EE_Bota]

If I remember correctly, and if I don't plenty here will, the main characteristics of a diode are their amp carrying ability, and the peak inverse voltage they will block. So are you having trouble finding a diode with those correct characteristics? It is perfectly fine to use a diode with higher current carrying ability, and higher PIV withstand, so I should think the options for a replacement diode would be pretty good. I'm not an electronics guy, but I think I am right about this for just a typical diode application. I saw a diode on Amazon with 6 amps capability, and a PIV of 1000volts for less than two dollars, but I have no idea what amperage you are looking for. Are there any numbers on the diode that will tell you anything about it?

 

[FergFan]

The only number on this diode is an 8. I'm having trouble finding a diode I can connect a 12gauge wire to, much less their amp carrying ability at this point.

 

[br1ghtnut]

Hello EE_Bota is correct... I might be able to help... Two diplomas hanging on the wall say that I am versed in Process Control & Robotics and ElectroMechanical Engineering; but you can get anything on line these days. The diode is in a wire harness to the lights of a 1953 tractor? Can you give me more details? Do you know the purpose of this diode? But, essentially anything with larger values would be okay. I got some mighty big diodes !!

 

[troutsqueezer]

I doubt if the diode needs to be huge. You can probably get away with using two legs of a full wave diode bridge which are commonly found, at least they were a few years back. Radio Shack used to sell them. Get the kind that comes in a square package with a hole in the middle for mounting to a chassis, not the TO-220 type.

Actually, a quick check on my part and I see Ray D. O'Shack still sells them. At 25 amps, you should be good. Search Result

 

[ironnut]

I am a bit puzzled by a 1953 tractor having a diode as part of its wiring. Is this diode shown in the electrical diagram for the TO30?

In 1953 transistors and diodes were in their formative years. High current semiconductor devices really didn't exist. If you bought a battery charger back then it had selenium rectifiers in it (bulky things with lots of fins). My 1967 Honda 160 had selenium rectifiers in its charging circuit. It sounds like this diode was added by a later owner. Is this a 6 volt system.? It is a bit difficult to understand the purpose of this diode in the lighting circuit. I could see a fairly large one 20 or 30 amp being put between the generator and the battery to take the place of a generator cut out.

Anybody have a wiring diagram for a TO30?

gordon

 

[ThomasH]

That diode would have to be a retrofit - possibly if the alternator was changed in order to light a light on the dash showing a charging fault or something like that. Otherwise, I have no idea what the diode is there for.

 

[banjodunn]

G'day something wrong with your wiring somewhere, it don't get much simpler than an early fergy wiring battery-switch-lights in that order alot did not even have a fuse in the circuit so a diode is definately not a factory fit. As for the sparks you got something must not be hooked up right.


Jon

 

[k0ua]

you have been given good advice about diodes and the old selenium rectifiers etc. here is an interesting paper if you are into early history of diodes and transistors.

Road to the Transistor

James K0UA

 

[EE_Bota]

I am a bit puzzled by a 1953 tractor having a diode as part of its wiring. Is this diode shown in the electrical diagram for the TO30?

In 1953 transistors and diodes were in their formative years. High current semiconductor devices really didn't exist. If you bought a battery charger back then it had selenium rectifiers in it (bulky things with lots of fins). My 1967 Honda 160 had selenium rectifiers in its charging circuit. It sounds like this diode was added by a later owner. Is this a 6 volt system.? It is a bit difficult to understand the purpose of this diode in the lighting circuit. I could see a fairly large one 20 or 30 amp being put between the generator and the battery to take the place of a generator cut out.

Anybody have a wiring diagram for a TO30?

gordon

I looked at several TO-30 diagrams online, even converted to 12 volts, but I didn't see a diode symbol anywhere.

I like Troutsqueezer's idea about using a bridge though, if he does need a diode. It will have the current, PIV, and ease of wiring necessary, and if I am thinking right, a built-in spare!