homemade EFIS system and EMI

Thanks everyone. A brief update.
With the new power supply the mini itx people sent me the problem
almost went away, I was able to do flight tests with it but .... very
rarely it would still cause enough interference to cut into the
Radio's, something clearly unacceptable as sooner or later it would
happen when the tower would be talking to me.

So I suppose I will pursue the linear regulator route. John you
mentioned there was an IC to take 12V and invert it to -12v, do you
know the part #?

Before I read the recent post I had all the TO-3's to make one and was
going to try and just omit the -12V and see what happens as I could not
find out what this was used for, but I see in the posts it is used for
serial communication which I do use. The ADC board I built sends over
the sensors data via serial and I log all the GPS NMEA data via serial.


I like the idea of linear regulators, low noise and a low part count.
There should not be a heat problem as the nose of the Long EZ has
circulating air (which is a bane at high altitudes).

Looking at the ATX power supply specifications they state there is a
sequencing of voltages and when everything is OK, a PW_OK line is
dropped low. I would rather not get into sequencing and keep as much as
possible to the K.I.S.S. mindset. Does anyone have an idea on whether
this is truly important? I was hoping to just apply power and be ready.


Thanks again to everyone and the recent replies from John, Evan &
UltraJohn










Evan Carew wrote:
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As a general rule, if you are thinking of solidifying such a design,
you
generally go out & purchase one of those hardened PC systems such as
PC104 or like. These systems come with features such as extended
temperature ranges, G tested, & slower clock rates so you don't have
to
use fans. Most of the systems I have seen in this class also have
slots
for CF cards & can get by on ~15 watts of power, or just about what
your
average night light is rated for.

Evan
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