PSN-L Email List Message

Subject: Re: Haunted system misbehaving again
From: Larry Conklin lconklin@............
Date: Tue, 19 Jun 2012 21:18:47 -0400


Hi Larry,

Not a silly question at all, but one I've considered in the past. Have 
carefully checked and cleaned around the pendulum, etc to get rid of any 
possible webs or critters, with no noticeable effect.

Regarding the enclosure, it isn't much bigger than it needs to be to 
enclose the volume surrounding the sensor.  And I have a couple of power 
resistors on an aluminum plate at the top of the box to try to create a 
temperature inversion, but I've never been able to convince myself that 
it makes any real difference.  Maybe I need to make it a little hotter.  
At one time I tried to take up as much of the empty space with baffles 
made of corrugated cardboard, but that didn't seem to help either and it 
made the cover of the enclosure surprisingly heavy.  I wound up 
scrapping that cover and making a new one out of celotex panels.  It 
would probably be a good idea to fill the empty space in this enclosure 
with something light and insulating, like styrofoam.

But none of those possibilities really fit the history of the problem 
very well.  I could write a small book on all the things I've considered 
and tried, several of which have seemed to cure the problem, only to 
have it come back months later.

I really don't have any real reason to suspect the electronics, other 
than I don't have any other ideas.  The basement is humid, so at one 
time I took the board out and baked it under a hundred watt light bulb 
for a couple of days, cleaned it and put it back.  No effect.
Since I can see corresponding glitches in the output of both channels, 
if there is a problem with the board it either has to be upstream of the 
point where the two channels separate, or possibly in the power supply.  
But, with the limited test equipment I have, I don't see anything amis 
in the power.  And at one time, I decided it was worth the trouble, and 
replaced the first stage op amp.  No dice.

So....  What other ideas have you got?

Larry

On 6/19/2012 6:52 PM, Larry Cochrane wrote:
> Silly question Larry. Are you sure the noise is not being caused by 
> spiders, also known as spiderquakes, or some other insect getting 
> inside the enclosure? I guess it could also be air currents inside the 
> enclosure. Do you have a lot of free air space inside your sensor box?
>
> Regards,
> Larry Cochrane
> Redwood City, PSN 


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