In reference to a simple, inexpensive engine monitor that doesn't take up
much panel space.
My home brewed unit uses old technology I had lying around: 80C85 CPU and
AD815 16 channel MUX - 8 Bit AD. The display is the same you gave to
Tracy: monochrome 20 chars * 4 lines with LED back light and very
sun-light readable. Parts cost of monitor is probably less than $75
without sensors.
All sensors I use have 0 - 5 volt linear radiometric outputs. About $20
for pressure sensors and $1 for temp sensors. EGT sensors are from $25 to
$ 40.
I thought of making a unit and offer it for sale but then you get
requests like: well, I'd really want 10 bits, etc. etc.
Finn
That is a fact of life when doing business Finn. Customers always
want what you don't have. Heck I want a 2.85:1 PSRU from Tracy.
You must make a decision to balance requested improvements and new features
with the cost of new developments and still stay in business. Not something
that can be taught in business school.
Dump the 80C85 and go with a PIC. Far more modern, up to date and evolving
technology (10 bits etc., etc.) There is a growing market for this stuff.
This newsletter is a golden opportunity for anyone that wants to market
stuff for the rotary. We are very focused and I will help anyway
I can.
Paul Lamar
Finn, I would like to know more about the sensors you are using. The
temp. and pressure sensors in particular. Low pressure sensors like for
the cooling system pressure seem hard to find. I sure would like to
find a sensor that can read airspeed and altitude -- as backup gauges to
the regular gauges.
Rino
I use Motorola pressure sensors. MPX4--- and MPX5---. Prices between $16 and $25
from Newark.
Biggest problem with them is they may not be designed to handle oil and fuel (gas)
and I imagine that most people would prefer more sturdy looking sensors (e.g. in
steel enclosures and 1/8" NPT fittings) but then you're talking $80 - $200 per
sensor.
For airspeed and altitude they will work just fine.
Temp sensors are Analog Devices TMP35/36/37 and National Semiconductors LM35/36.
EGT conditioning are Analog Devices AD595 (outputs 0 - 10 Volts for 0 - 1000C).
By using linear sensors all you need is a lookup table with offset and multiplier
for each channel (sensor) - relatively simple to program. Ok, you also need number
of digits, decimal position, display position, min and max limits.
Finn
Thanks for the information Finn. I'll work on that, I use LED displays
for each gauge.
How do you package the LM35 to read water and oil temp?
Rino
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