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[aprssig] EMI Help (fixed)

Andrew Rich vk4tec at hotmail.com
Fri Aug 13 04:50:36 UTC 2004


Thanks to all that helped. Here is what I did :-

1. Shortened the LCD data bus lead by half
2. Changed the code so there are less interrupts (less chance of glitches)
3. Added a 0.1uF across the Vin and Vout (I already had 10uF on Vin and V
out)
4. Added a 0.1uF across the GPS in data line
5. Wound the input voltage leads in a ferrite bead.
6. Moved the caps closer to the voltage regulator

Now I am up against thermal stress. I turned up the heater in the car and
the regulator started to give up.
Bring the temperature back again and all is well.

What is the best way to get from car volts (14Volts) down to something
acceptable for a 5 volt regulator ?
Most of the problem from running off the car is heat dissapation. Getting
from 14Volts down to 7ish volts.
Voltage divider ?

Cheers Andy VK4TEC
----- Original Message -----
From: "Andrew Rich" <vk4tec at hotmail.com>
To: "TAPR APRS Special Interest Group" <aprssig at lists.tapr.org>
Sent: Friday, August 13, 2004 7:15 AM
Subject: Re: [aprssig] EMI Help (extra info)


Thanks to those who replied.

To show you what I have setup, i have included a photo

http://www.tech-software.net/139_3905.JPG

and the schematic.

http://www.tech-software.net/nmea6.jpg

Ideas ?

Plan of attack

1. Wrap aluminium foil
2. Metal case
3. More caps
4. Shorter bus run to LCD
5. Try another GPS
6. Put CRO across the BUS rails with the car running in the driveway









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