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Post by einy on Dec 14, 2015 17:28:12 GMT
Interesting 'work around' on Snowbird1's part ... I have to go with a windshield full width of cockpit here (as well as tall enough that I am looking through instead of over it), and it's possible that I may have to use two wipers. The State Patrol guy said wipers can be manually activated or electric (my choice), but have to clear an area that spans the sight lines from the left wheel top across to the right wheel top. Still some design work to do on my side, but I'll post what I come up with in my OH Registration thread, and what the result is from the inspection come Spring.
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Post by jon on Dec 30, 2015 6:06:04 GMT
I am working on adding my fancy gauges. After a lot of debate, I ended up putting holes (using a large hole saw) into the fiberglass cowling. It is a little awkward because of the curve of the cowling (it is not flat), but it actually worked out OK.  I mounted the GPS on top:  I discovered a while back that the car does not charge without the gauge cluster connected. On the 90's (and other years I assume) the charging light is necessary to to energize the alternator rotor windings or regulator (or something to that nature). Here is a diagram. The W/B wire going to location 2 out of the alternator is needed:  Here we find that on the gauge cluster, going through the CHARGE light:  I am going to try and use some resistors of adequate power to simulate said light bulb. |
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Post by einy on Dec 30, 2015 13:18:17 GMT
Why not just put a replacement stand-alone bulb in your instrument cluster?
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Post by jon on Dec 30, 2015 14:16:44 GMT
I certainly could, but I don't like the idea of a burnt out bulb making my car not charge. Properly sized resistors will be more reliable imo.
Granted, That is probably the way it works now (unless there is a resistor in parallel with the bulb that isn't shown in the wiring diagram).
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Post by snowbird1 on Dec 30, 2015 15:09:39 GMT
The advantage of the bulb is that when it illuminates you confirm a circuit through the wiring, the rotor brushes and the rotor. The bulb goes out when the generator is charging and the bulb has voltage on both sides.
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Post by dietcoke on Dec 30, 2015 18:24:31 GMT
I did the same thing with my gauges. No issues  |
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Post by jon on Dec 30, 2015 23:47:56 GMT
The advantage of the bulb is that when it illuminates you confirm a circuit through the wiring, the rotor bushes and the rotor. The bulb goes out when the generator is charging and the bulb has voltage on both sides. I don't have a problem with a bulb to give a us an indication, but rather that charging relies on said bulb not burning out ever. It should last a long time, decades in fact, but it's still just a light bulb - easy failure point. If they had added a parallel resistor around the bulb it would add redundancy and only cost about 1 cent more. Maybe it has such a resistor, but it is not shown in the wiring diagram. |
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Post by snowbird1 on Dec 31, 2015 15:37:06 GMT
[quote
If they had added a parallel resistor around the bulb it would add redundancy and only cost about 1 cent more.
[/quote]
But you would not know it had stopped charging until the battery went dead - unless you have a ammeter or voltmeter.
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Post by jon on Dec 31, 2015 16:18:07 GMT
[quote If they had added a parallel resistor around the bulb it would add redundancy and only cost about 1 cent more. But you would not know it had stopped charging until the battery went dead - unless you have a ammeter or voltmeter.[/quote] No, if there is a bulb and a parallel resistor, the bulb still works as normal, indicating charging is not working. The difference is that if said bulb burns out, you can still drive around (charging still works). If there is no resistor, when the bulb burns out you lose indication AND lose charging ability. You will only find out when the battery dies. The operation of your car is dependent on a light bulb. |
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Post by jon on Dec 31, 2015 20:02:14 GMT
So upon further inspection, the alternator regulation is entirely dependent on the value of the resistance of the light bulb. This is like 1940's technology. It is staggering to me that the function of the car relies on a tiny light bulb that is tacked on to the gauge cluster making contact with a flexible circuit board.
I have some 2W power resistors, I believe 330 ohms. Tried with one, and a diode (as the wiring diagram shows), and the voltage gets regulated over 16V. I tried with 2 resistors in parallel and the voltage is regulated below 12V.
It looks like I have to use the light bulb. It is unclear what function this provides to the regulator, but its value is critical. Granted, I could use a bunch of fixed resistors in series and parallel to reproduce the resistance, but that seems like a lot of work.
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Post by dietcoke on Dec 31, 2015 21:16:44 GMT
Just get a self exciting alternator. Done.
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Post by snowbird1 on Jan 1, 2016 16:04:22 GMT
Interesting experiment - the output of the AC generator is controlled by the current through the rotor unlike the old DC generators that had a constant output and just 'wasted' the excess current. Once the generator is charging and the light goes out and there should be no current flowing in the exciter circuit (same voltage on both sides of the bulb and resistor) and the regulator is in control. You could probably calculate the resistor you need, using Ohm's law, by measuring the current in the original circuit with the bulb lit.
I once tried to demonstrate the need for the exciter circuit (on a different vehicle) by disconnecting the wire and starting the engine - the generator charged just fine - realized there was enough residual magnetism to make it charge.
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Post by jon on Jan 2, 2016 18:16:40 GMT
I ended up soldering the bulb and a diode into my harness for the new gauges. Fixed everything, now it regulates at 14.4 again.
Odd way they designed this.
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Post by jon on Jan 2, 2016 23:01:26 GMT
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Post by zeitgeist on Jan 3, 2016 1:08:59 GMT
Looks really good Jon. The visibility and colors match nicely.
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