| Author |
Message |
Chuck Newman (Chuck_newman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 20, 2005 - 4:33 pm: | |
Does anyone know the empty ohms and full ohms for the factory installed fuel sender in the MCI 102 A,C series buses with standard 149 gallon tank.
Thanks,
Chuck Newman
Oroville, CA |
RichInternational Bus & Parts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 20, 2005 - 4:46 pm: | |
Hi Chuck,
We show it to be 240-33 ohms. Let me know if you have any questions.
Rich
800-468-5287 |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 20, 2005 - 10:32 pm: | |
Hey Chuck
Industry standard resistance range for senders (pressure, tempurature, level, etc.) is 240W for the low value (ie. empty) and 30W for the high value (ie. full). This can be read with a standard multi-meter.
I can send you a basic design for an inexpensive (<$20) dicreet logic Analog-to-Digital converter for reading a sender and putting out an 8-bit binary value (0-255) 10 times per second, assuming that you are really into electronics...
Cheers!
Tim Strommen |
Chuck Newman (Chuck_newman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 20, 2005 - 11:25 pm: | |
Thank you Rich for the information. Also, it reminded me I need to call you about Ramco mirror mounts. I have a different idea than what we discussed at Rickreal.
Tim, thanks also for the resistance info. And yes, I would like to get the schematic for the D/A converter. 8 bits is pleanty resolution for this application if the converter is stable.
Actually I wanted to digitize three air sources also, but I'm to cheap to get a Dakota Digital unit with quad display. And to me, the display would look strange using only three of four readouts. If your D/A design works, I could have used that. But today I purchased dual and single input analog air gauges in the Classic Instruments white hot series.
Anyway, I'll try the D/A circuit on my fuel sender since all the other engine ECM parameters are on the LCD screen. Pdf works best for me, or email for my mailing address.
Thanks again,
Chuck Newman
Oroville, CA |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 21, 2005 - 12:14 am: | |
Tim, could you send me a copy of that info? I would be very interested in setting up some of those readouts.
Thanks.
Tom Caffrey PD4106-2576
Suncatcher |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 21, 2005 - 12:25 am: | |
Oh, Chuck.. it's an A/D converter not a D/A. I'll need about a day or so to format it into a single PDF file... and yes, after you create the basic "clock", expansion is VERY easy and cheap. The basic jist for anyone who's interested, is a Resistor-Capacitor circuit.
The clock is contructed using a 12-stage counter, an 8-bit magnitude comparator, some basic AND/XOR/NOR gates, an N-channel MOSFET, and a timing source (I'm using a TTL/HCMOS oscillator, you can build a 555-timer based clock also...) at 7,886.477913Hz. This will make pulses at about 3 times what is needed for an 8-bit reading (.0333333 seconds to charge the capacitor, .0333333 seconds to read how long it takes for the capacitor to discharge through the sender to ground, .0333333 seconds to set the data to the latch).
Each channel gets a 100W resistor for regulating the capacitor charging current, a P-channel MOSFET to charge the capacitor, a 3-in/1-out AND gate, a 12-stage binary counter for reading the clock pulses allowed through the AND gate, an octal-latch for data holding, and a 100mF capacitor (~$2.00 per channel). This will give the A/D converter a 0W to 255W range. Anything below 25W is considered a short, and anything above 245W is considered an open sender. As you can see by the description, it has the possibility to be a very powerful digital display data source. If you were to use a microprocessor, you could easily indicate sender faults, and with simple math you can use 7-segment displays to display numerical values for the readings. In my application, I'm using the Maxim Semiconductor ICM7212 4-digit LED display driver (which features the CODE-B font, "0-9,blank,-,L,E,H,P"). With the programming in the microprocessor, it can display "-5H-" for short (looks like -SH- on a 7-segment display), "-H1-" for upper limit of sender range, "-L0-" for low end of range, and "-0P-" for open-sender. The stability of the reading will depend on your display. I'm using a microprocessor which has basic averaging capabilities, and displays a 2 second averaged reading. You'll have to decide how you want to handle the data once it's digital.
I designed the fast refresh-rate so that the custom speedo and tach could show near-real-time readings, and that changes could be logged in my "black box", which records any change over 26 8-bit inputs (for 32-digital inputs, and 22 analog senders). This way if I buy-it in a wreck, someone could find out what condition my rig was in and what I was doing before the crash. But the better reason for logging this is tracking the engine and chassis systems over time (easier to find developing problems by downloading and comparing the vehicle's telemetry and setting thresholds for service...)
I'll ask for your patience in getting the circuit "all written up", but it should be by this Saturday at the latest.
Cheers!
Tim |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 21, 2005 - 12:33 am: | |
When I finnish formatting the circuit, I'll email Ian to see if I can have it posted to the BBS. I think that anyone who wants this circuit should be able to get their hands on it (and not pay ~$120 for a Dakota Digital unit...). I'll also go ahead and spec the 555-timer clock source for those who don't want to try to track down a suitable oscillator.
Cheers!
Tim |
Mike (Busone)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 21, 2005 - 12:18 pm: | |
Thanks Tim, I think a lot of us will benefit from that sweet little circuit. |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 23, 2005 - 10:19 pm: | |
All,
I'll need a few more days or so...
I started drafting the circuit, and in true BBS style I began considering the YMMV problem. I'm making a small change to the layout, adding a potentiometer, a dummy sender, and display (basically a DOM) for calibration. This will make it more accurate in all of your installations (wiring and distance considered). The change was motivated by my original design being "tuned" for my application. Not everyone is as savy with electronics as I am. I'm inserting a local display with a tuning trimmer-pot and a calibrated resistance referrence for setup and tune-ups. Don't worry, it's still really cheep compared to this @ $545.
I have an interview on Monday, and I'd like to test the circuit over some different temeratures to make sure these new parts aren't gonna make bad readings. So bear with me until about Wednesday.
Thanks all!
Cheers!
Tim
P.S. One thing for everyone to keep in mind is that this is a binary sender-reader. All of these parts DO NOT include the cost of senders or the actual display, so keep this in mind when considering using this on you rig or generator set. -T |
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