Electrical question

Clyde Scott - Moultrie, GA.

As for the coil power, It runs OK off the generator once started.. I know the resistor placement will need to be just after the on/off switch and prior to the amp meter which is where the generator power in inserted.

CS

Clyde Scott - Moultrie, GA.

I'm not sure where Clyde will end up with this, but if he decides to go the start on 12v, run on 6v route, this might be a good place to use one of those solid state voltage regulators, LM309K. With those you put 12 volts in and get a smooth and solid 5v out. If he rigged a by-pass ignition wire to it, and the coil could stand a 12v hit for a bit, it would crank furious, spark like all get out, and then settle in to run on a cool 5 v at the coil.

Only problem is, I just don't have any idea how much draw a coil has. You might have to run 2 or 3 in parallel to spread out the case heat (or maybe use a fierce heatsink), but I think 5 volts would run it after it had fired up.

Frank-in-Tallahassee
70D // 855

Doesn't an item called a "voltage reducer" sound an awful lot like a wire-wound ohm and a half, 4 amp resistor ?

I think that's the same unit that some of the old car parts pages are pushing.

What I wish they'd make is a unit similar to the LM309K, only with an output of 6 or 6.5 VDC, and at a couple amps. The 5 VDC one is great for TTL logic circuits, but not very handy for coils.

Frank-in-Tallahassee
70D // 855

That Nat Semi part is rated at somewhere around 800 to 1000 mA. I measured the draw of a 6 volt coil on my 4 banger tractor at ~4.7 amps (part of playing around to see how many lights and junk I could hang on the system). Also measured 6.8 volts going to the coil, wonder how it would run with 5V going in. The prices for something that handles that much current and spits out 6V escalate fairly dramatically -- unless, as you say, he home brews the thing and has a monster heat sink.

Steve

I had a similar problem with a 6 volt starter on a tractor a week ago. It had literally frozen over the winter. Pulled the starter, replaced the brushes, greased up the shaft at front and rear and cleaned it with contact cleaner. Turns over as fast as my 12 volt machines now. That fix didn't cost much either! I've got a 6V Optima battery on that machine which is rated at 850 CCA - they show up for 40 to 50 bucks on Ebay every once in a while. That's probably the main reason for the fast turning -- but nonetheless I'd take a look at that option first as an easier path than re-engineering the electrical system.

Steve