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user9253
Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan
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 Posted: Fri Jan 08, 2010 5:52 pm Post subject: Electronic Dead Reckoning Distance Calculator |
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Back in the days before GPS, I carried a circular slide rule in my shirt pocket. Once the ground speed was set, the slide rule would tell me the time en route opposite the distance scale. Later in the flight, I would determine the distance to go by looking at the distance scale opposite the remaining time. Then I would measure that distance on the chart and try to find a landmark on the ground that matched the chart. Do not ask me if I ever got lost. 
Wouldn't it be nice if there were some way to automatically calculate the distance to go without having to match up the scales on the circular slide rule? What I needed was a poor man's DME. I made one utilizing the constant function of an electronic calculator. Dividing the aircraft ground speed by 1200 gives the distance traveled in 3 seconds. All I have to do is subtract that 3-second distance from the total by pushing the EQUALS KEY every 3 seconds. That is accomplished automatically by the attached circuit that contains a crystal-controlled oscillator and divider and solid state relay. There are probably other ICs or microprocessors that will do a better job, but this is the way that I did it. And of course GPS is much better as long as it works. There might be other applications for this circuit besides moving vehicles, i.e. anything that moves at a constant rate.
http://public.bay.livefilestore.com/y1ppOv3v2Wbgtq80VIypr95YNkF1OXb94DIJlAOGJjOaMH01g82rhlsInEKh0RMLu0M2QKEvsMg3eqsaeibksk3Dw/Distance%20Calc.pdf?download
Joe
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nuckollsr
Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS
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| Posted: Mon Jan 11, 2010 5:44 am Post subject: Re: Electronic Dead Reckoning Distance Calculator |
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Joe,
Pretty slick. Your project reminds me of some other instances many moons ago where cheap calculators where pressed into service as event counters. Again, repeated actuation of the equals-key produced an increment to the display. When counting this was an integer of 1, for your application, the increment is a calculated variable based on present conditions.
A thought for further enhancement of your recipe for success. A PIC microcontroler could replace both IC's and the crystal. The jellybean processors have built in timers that are probably accurate enough to serve in this short term prediction mode. Further, many of them have trimming features for the internal oscillator that permits an improvement on accuracy at the time the device is assembled.
Your total parts count could be reduced to battery (Lion button cell?), controller, opto-coupler, resistor and perhaps one Vdd to Gnd bypass capacitor. Obviously, the same device could be used on terrestrial journeys as well . . . especially in vehicles on cruise control.
This would be a good project for budding electro-wienies offering a mix of electronics, small scale fabrication, adaptation of existing products to new applications, perhaps a bit of software and an example of how one can convert the 8th grade algebra class story problem into a recipe for success.
Thanks for sharing.
Bob . . .
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user9253
Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan
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| Posted: Mon Jan 11, 2010 7:47 am Post subject: Re: Electronic Dead Reckoning Distance Calculator |
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Bob,
Thanks for your comments. I am really proud of this project, but did not expect many replies because GPS has made dead reckoning obsolete. You and another friend suggested using a PIC micro-controller. Unfortunately I know very little about them. I understand that a programmer is required. It was fun learning how to program the CD74HC4059 counter-divider. Learning how to program a PIC micro-controller should be fun too. There are programmers listed on eBay from $15 to over $200. Does anyone have a suggestion on which one to buy? I want to build a capacitance to voltage converter for a fuel gauge like this:http://www.rstengineering.com/kitplanes/KP0007/KPsch.jpg
Can a PIC micro-controller replace much of that circuit?
Thanks, Joe
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klehman(at)albedo.net
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| Posted: Mon Jan 11, 2010 8:44 am Post subject: Electronic Dead Reckoning Distance Calculator |
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Joe
Take a look at the AVR BUTTERLY for $20. from digi-key.com
Amazing amount of hardware on the tiny development board.
No programmer required just an RS232 (serial port) on your computer.
Software STUDIO4 is free.
Ken
user9253 wrote:
| Quote: |
<fran4sew(at)banyanol.com>
Bob, Thanks for your comments. I am really proud of this project,
but did not expect many replies because GPS has made dead reckoning
obsolete. You and another friend suggested using a PIC
micro-controller. Unfortunately I know very little about them. I
understand that a programmer is required. It was fun learning how to
program the CD74HC4059 counter-divider. Learning how to program a
PIC micro-controller should be fun too. There are programmers listed
on eBay from $15 to over $200. Does anyone have a suggestion on
which one to buy? I want to build a capacitance to voltage converter
for a fuel gauge like
this:http://www.rstengineering.com/kitplanes/KP0007/KPsch.jpg Can a
PIC micro-controller replace much of that circuit? Thanks, Joe
-------- Joe Gores
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user9253
Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan
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| Posted: Tue Jan 12, 2010 6:38 am Post subject: Re: Electronic Dead Reckoning Distance Calculator |
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To Peter, Bob, Ken, Ed,
I know that I can build that capacitance-to-voltage-converter fuel-gauge circuit designed by Jim Weir using discreet parts that do not cost very much. Using a PIC microcontroller will cost more in both time and money to purchase the programmer and to learn how to use it. On the other hand, new technology is exciting and it will be fun to learn a new skill that can be used for future projects. Thanks for your suggestions and advice.
Joe
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