Alternator Warning Lamp Circuit Question

[mudnut]

Not hard to change a globe on a GQ.

I think an LED might be too sensitive and would glow at the drop of a hat and would get you wondering whats up.

A globe can have a fair bit of current flowing through it before it glows, and its resistance actually changes in proportion with the heat produced as more voltage is applied. That would have to be taken into account too.

[mudnut]

I would like to the whack the probes of my scopemeter across the brushes of a working alternator. It would be interesting to watch the voltages change with the load.

[dom14]

I would like to the whack the probes of my scopemeter across the brushes of a working alternator. It would be interesting to watch the voltages change with the load.

Not without a possible injury.
What kinda scope have you got?
Do you have a link or something that I can see?

BTW, I just tried to imagine how much that I've learnt in a few days about the automotive charging system.
I almost feel "enlightened".
Imagine what would happen if I have the experience and the level of understanding you blokes have!!!

BTW, it's great you have a scope. The stuff you can do with that would be endless.

[Yendor]

I would like to the whack the probes of my scopemeter across the brushes of a working alternator. It would be interesting to watch the voltages change with the load.

That would be the only way to see exactly what is happening. A voltmeter would be way to slow at reading the values and only give an average reading.

[mudnut]

I have an Allsun scope which I bought from china. It looked a bit more rugged and repairable than the first one I bought. I accidentally spiked the first one and found it was all plastic welded and impossible to fix. It turned out I was right about the Allsun as the on/off switch was jiggered within a month. I used a switch off of a Sony walkman to fix it. Using the allsun is like using a pitchfork to eat spaghetti it is so agricultural. Wouldn't touch any of their products with a barge pole.

[dom14]

I have an Allsun scope which I bought from china. It looked a bit more rugged and repairable than the first one I bought. I accidentally spiked the first one and found it was all plastic welded and impossible to fix. It turned out I was right about the Allsun as the on/off switch was jiggered within a month. I used a switch off of a Sony walkman to fix it. Using the allsun is like using a pitchfork to eat spaghetti it is so agricultural. Wouldn't touch any of their products with a barge pole.

Ok, cool. If I've got the message, you're telling me to stay away from the brand you have??!!

Is this the one?
http://www.all-sun.com/en/d.aspx?pht=1184

[GeeYou8]

Having just ripped the dash out of the Excel I will be looking to fit an alternator light (& oil pressure light) on the starter box.
The Excel project is a speedway car for my 10 year old boy.
Graham

[mudnut]

Yup, Dom. Only get one If you are prepared to take the unit apart, strip the guts of both the on/off and ac/dc butto, then solder two similar style but heavier duty switches in parrallel to the pc board. It is unfortunate that they skimped on such vital components. I only did the one switch where as in hindsight I shoulda done both.

I also got a small shock from the multimeter leads while checking a 240v circuit with the scope probe. So they have to be removed when the scope is used.

[dom14]

Yup, Dom. Only get one If you are prepared to take the unit apart, strip the guts of both the on/off and ac/dc butto, then solder two similar style but heavier duty switches in parrallel to the pc board. It is unfortunate that they skimped on such vital components. I only did the one switch where as in hindsight I shoulda done both.

I also got a small shock from the multimeter leads while checking a 240v circuit with the scope probe. So they have to be removed when the scope is used.

By small shock, you mean you didn't get the full 240V shock which has the potential to kill you?!

[Throbbinhood]

I've had a quick read through this, and am happy to say it is all well above my head and I understood next to none of it.

One thing I didn't see mentioned though, and perhaps I missed it, but is there any difference between different alternators in the way they excite and regulate and the circuitry needed? I only ask because I believe Dom has upgraded to a 110/120amp EF Falcon alternator, and I'm not sure if it's been taken into account (or if it needs to be, or makes no difference perhaps). If it's been taken into account already or doesn't matter and I've missed it, my apologies.