In a message dated 7/3/2006 9:34:04 AM Central Standard Time,
spamiam@comcast.net writes:
> So, 2 questions. 1) what ON/OFF frequency should I expect for a properly
> functioning stabilizer, since I do not have a good one to test. 2) what
> should be making these things go bad and do it in DIFFERENT ways? As far as
>I
> can tell, the gauges are working correctly and the resistance of the gauge
> circuit seems OK. I am not sure what kind of current draw they are supposed
>to
> have, but it seems OK at first glance. THe last stabilizer lasted maybe 300
> miles, if that.
I have not dissected any failed stabilizers but I have had only one fail and
that was 20 years ago. But they are pretty simple devices. If they fail open
I would suspect either a bad connection inside or the points are burnt up.
Excessive current might be a culprit if the latter is the case. When they fail
closed it could be because the heater wire opened up or there is a poor
ground connection. The TR6 unit grounds through the case. On a TR6 it is
mounted
to the back side of the speedometer. Usually the internal connection is where
the can is crimped onto the phenolic base which is an invitation for a failed
connection. But any connection between the stabilizer's case and electrical
ground will cause the same symptom.
>
> Interesting electronics side note: When I was awaiting a spare stabilizer
> many months ago, I threw together a linear 10 V regulator. It had NO power
> filtration/spike protection, not that I thought I would have many transients.
>
> Well, WRONG. The regulator died in several hours of running, but was great
> while it lasted. I think I might make a new, more hardy one. Maybe with a
> 1000V/1A diode feeding into 1000uF cap on the power input along with a 600W
> 20-something volt bidirectional TVS as well. Does anyone know if this will
>be
> enough protection, or is there something more I should have on it?
The trick to using shunt type spike protection is to provide some source
impedance. Sometimes the wire is sufficient but since the wiper motor
switching
off is a likely source of spikes and it is fed from the green wire (like your
voltage stabilizer) it may be more intimate to the stabilizer than is
comfortable. You might try a 1 ohm resistor in series with the diode. This
will limit
the currents resulting from the spikes making your spike suppression more
effective.
>
> I had considered the issue of the relative ly poor efficiency of a linear
> regulator, but, you know, the stabilizer's resistance wire probably
>dissipates
> a half watt or more. That is probably about 2% of the entire output of my
> generator's full power output!
>
To calculate the linear regulator's power dissipation you would need to know
the current required by the gauges. I don't know what that value is but using
a 100 mA value for each gauge and a total of two gauges you get .2 A.
Assuming a healthy generator (unloaded) and a battery voltage of 14.5 V and an
output voltage of 10 V the power dissipated would be (14.5 - 10)*.2 or 0.9
Watts.
If the generator is loaded the battery voltage will drop some to, say, 13.5
volts. Now the power dissipated is only 0.7 watts.
A fully loaded generator producing 20 amps at 13.5 volts is generating 270
Watts. So you linear regulator is consuming 0.25% of the generator's capacity.
Don't loose any sleep over it.
Cheers
Dave
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