Hi Stu, and Listers,
I'll comment on your comments:
I've been running my prototype regulator circuit for about a year now, and I
would guess that it's seen just about every environmental condition that it ever
will, except for maybe really high under-dash temperatures. However, the 317AT
is good to 125 degrees C, and I don't think we're going to go there. I've had to
boost the car, I've started it in -20 degrees C, I've run it with the wipers and
heater fan turning on and off, all with no apparent ill effect. While I built
that prototype without input protection, I'd do any other units with a Zener
diode across the input to protect against large spikes. The 317 is internally
protected against overheating and short-circuits on the output side.
As far as the old 1940's tech vs new 1970's technology argument goes, I can
offer only this: How long has that "new" mechanical regulator been sitting on
the shelf? What is the tolerance on the output voltage? How temperature stable
is that thing anyway? There are a lot of Tigers and Alpines out there with
"cooling" problems that are actually the regulator's fault. I agree that a
properly adjusted mechanical regulator will be as good as the electronic one,
and bombproof to boot, but today it's way easier to build an electronic
regulator than to refurbish a mechanical one by filing the points and then
tweaking that bimetallic strip.
If anyone is interested, I will rebuild your dead or questionable regulator.
Theo Smit
tsmit@home.com
tsmit@novatel.ca
B382002705
> -----Original Message-----
> From: STUART_BRENNAN@HP-Andover-om3.om.hp.com
> [SMTP:STUART_BRENNAN@HP-Andover-om3.om.hp.com]
> Sent: Friday, July 16, 1999 9:38 AM
> To: tigers@autox.team.net
> Subject: Voltage regulators
>
> A couple comments:
>
> As an old analog engineer, I can tell you not to worry for one minute
> that the LM317 based panel voltage regulator would not be accurate or
> stable enough. Consider for a moment the piece of crap it was
> replacing, which you were happy with until YOURS failed. The LM317
> design will be far more accurate, and far more stable over temperature
> than required.
>
> My concern is that the transients in the car's electrical system could
> damage the regulator, unless there is some sort of protection on the
> input side.
>
> I just sent an Email to my friend at NSC, for his opinion. I can't
> remember if he designed the LM317 or not, but he's in the right
> department, and messes around with cars too (old beetles).
>
> Another thought: Your original panel regulator lasted from the mid
> 60's until recently. Many, like mine, are still working fine. Why
> wouldn't the replacement, built out of the same stuff, last just as
> long?
>
> Stu
|