History Transistorized Ignition

Its a silicon controlled rectifier.. Its doing the switching work that the points used to do but at a very low level. At least that's what I think it does. I'm an electrician but I'm not into electronics.. Hopefully somebody with an electronics back ground will shed some light on this..

My buddy had a 66 GTO and had one of those Tiger CD on its ignition. He never changed points in 5 years he owned that car..

 

A SCR a.k.a. thyristor is an electronic component that works as a auto resetting switch. In a CDI system you first charge a capacitor to a few hundred volts, then you activate the SCR and discharge that through the ignition coil. Once the SCR has been activated it remains open as long as there's enough current going through it, i.e. until the capacitor is very close to empty. Then it automatically shuts off, the capacitor can be charged again, and the entire process can start over.

The SCR can only lead in one direction. There is a similar component called triac that can lead in both directions. You can find them in things like lamp dimmers used on AC. It opens once the AC input voltage has reached the set level, and shuts off automatically every time the AC p***es 0V.

 

Thank you so much G... You made that real easy to understand..

I put an electric radiator fan in the cab of my elCamino to help defrost the windshield. I tried to connect a house 120 volt AC dimmer to the fans circuit thinking it would lower the speed when I wanted to slow it down. When I connected this dimmer up to the positive side of the fan circuit nothing happened. Is that because of the TRIAC?

I ended up getting a DC speed control on e-Bay and they work real nicely.. They were very well made and only $5... I get some very good deals on e-Bay..

 

That dimmer may have used a triac or something else, there are other versions too, but yes, electronic AC dimmers are indeed very different from DC equivalents and most versions only work as intended, AC versions can't handle DC and vice versa.

 

I still have a Heathkit Oscilliscope,made from a kit. It still works, but needs 1 new variable pot. The knob got broken during the last move... I'm soooo old

 

Tube type, or transistor? They are great. I bought one for $40 and it sniffed out some ignition trouble I was having right the &@$k away. Took a while to decipher some of the squiggles, the finer points of diagnostics but in general they work really good at showing what's what.

I've seen plenty of multi-page marathon epic saga troubleshooting threads on many different websites, chock full of "could be this and could be that", when a couple minutes with the engine on a scope would have pointed him in the right direction, or at least eliminated a whole bunch of possibles.

 

Pontiac was one of the first manufacturers that "experimented" with the electronic ignition on their HD engines around 1960, of course Smokey Yunick was involved..

 

I have a Mark 10B box on my El Camino, found it in my grandfathers stuff when I cleaned out his stuff in the 90's. Worked for awhile now it's just for looks.

 

The same goes for most electrical issues and cheap, basic multimeters too. Five minutes with a five dollar meter can often tell you exactly where the problem is, or at the very least narrow it down to a few possibilities. But people still want to guess and replace one part after another, until they've spent $300 on things they didn't need before they figure out a corroded five cent connector was the problem all along.
Whyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy?!?

 

Thanks fo the info. I may indeed run this set up. It’s there and paid for. And was functioning the last time it ran according to Wesley.he said it did very well. So why not.
Any particular reason the silicon spark plug wires are considered above the solid core ?