Warning Light Assimilator

After more than a year, I am about to get my '74 Commando basket case back to its former glory ...I am currently working through wiring issues.....here's what I have: 3 phase alternator, Podtronics regulator, Trispark electronic ignition, relays for the headlight and horn, and fuzeblock....I have converted to negative ground.....now working through the electrics to ensure that everything works....I have come to the charging light.....doesn't work when the switch is on.....this leads me to the warning light assimulator.....what is the proper hookup, given the situation above?....now have brown/white to one terminal, green/yellow to another (I know this is not right since I now have a Podtronics)' and red to the third (also not right since red is no longer ground).......thoughts? Thanks!

The assimilator take he warning light to ground. When the bike starts and the alternator starts producing voltage it opens the circuit in the assimilator causing the light to go out. It is basically a relay, but instead of using a coil to open the contacts it uses a heat sensitive type of wire. They draw a lot of current for the job they do. I would look at the CoolCat 3AW for a negative ground system. It is a solid state unit and costs about $25.00. Wiring is simple. One wire from the light, one wire to ground and one wire from any one of the alternator leads.
Pete

There's a better solution: http://www.sparkbright.co.uk/sparkright ... onitor.php

I just put one of these in place of the charge light and it tells you a lot more. The charge light/assimilator looks at the AC output of the alternator and simply tells you the alternator is putting out. It doesn't tell you if there's any DC output. You could have a bad zener and everything simply going to ground.

I'm entirely happy with the sparkbright. When you turn the ignition on it goes through a self test then glows amber - healthy battery. With the engine running and the output > 13.2 VDC, green light. You can read the rest on their site. I just wired it to the ignition switch and ground.

It's just bright enough to see in full sun and dims itself at night. It's reassuring to see the green light and know all is right with the electrics.

Thanks for the info guys.....I am hoping to stay with the stock system if I can......just want to know what goes where, based on my configuration..

Electrically speaking, I have almost exactly what you describe for your 74 850. Also had the same puzzle as to what to do with the red light. I hooked it up to an oil pressure switch instead. Here's the original post...

Re: oil pressure switch in Commando electrical system

Postby dgraham42 » Mon Jul 14, 2014 8:07 pm

Slightly off topic, but related. When I converted my commando to negative ground there was no longer any thing to drive the red warning light as its signal came from the warning light assimilator. Instead, I added an oil pressure switch to the rocker feed oil line circuit and drove the light off the switch. From an operational perspective for the light, its exactly like it was before. Both oil pressure & voltage from the alternator/ rectifier are rpm dependent (no battery in older system). It even flickers now and then at low low rpms. It's not as good as a gage, but it's better than nothing. A little more obvious you have a problem too with that red light glaring at you.

Regards,
Don

whreid,

One side of the warning light bulb gets its voltage from the ignition switch the other side goes to the the assimilator "WL" connection, The "E" connection on the assimilator goes to ground (earth) the "AL" lead goes to any one of the alternator wires. I don't believe the "WL and E" are polarity sensitive. When I converted to a three phase my assimilator only lasted a short time before it stopped functioning, that is why I went to a solid state unit. Upon dissembling my old unit I did not see anything physically wrong with it, but it made me realize that it functions like a bread toaster. Electricity flows through a piece of Nichrome wire. The heat produced causes the wire open a contact. I don't like the fact that the assimilator is taking current from the alternator, through a piece of Nichrome resistor wire and then to ground. Very low tech and inefficient. That is why in 1975 Norton went to a solid state unit.
I hope the wiring information is helpful.

Pete

Thanks, Pete.....this is what I needed......

Bill