BS use in Automobile - What power source to use
franklin9090
Posts: 59
I have a project that I am starting and I will be using a BS1 or BS2 in an automobile.
I was thinking of using a 12v power line from the car, but was unsure if I could do that safely (without damaging my BSs).
How do I make sure I don't overload my BSs? What are some other things to consider?
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I was thinking of using a 12v power line from the car, but was unsure if I could do that safely (without damaging my BSs).
How do I make sure I don't overload my BSs? What are some other things to consider?
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Comments
Twisted Pair....
It sounds like you are telling me that I need a voltage regulator to bring the car's 12vdc down to 5vdc. Is that correct?
If so, how to I go about finding the appropriate regulator? What do I look for? How do I spec it?
For external devices, in this project, I am going to be using some kind of an encoder to determine speed.
Thanks.
There are many 5v regulators out there. Do you have a Radio Shack near you ? What kind of power is needed for the encoder ? (Volts & Amps )....
I have a Radio Shack about 4 blocks away, should I look in their catalog? How do I know I have the "right" one? Anything I should look for?
On the encoder, I have not determined which one to use.
To explain my project a bit more, I have a 1989 Mitsubishi and the speedometer broke. The cable is fine but the meter is broken.
I would like to attach an encoder on to the cable and use a BS to read the RPMs and convert to miles per hour, and display this on an LCD.
Any recommendations on encoders?
This is my first BS project so its a challenge but I think I am headed in the right diretion. Any advice?
THanks.
If you’re going to do an automotive project the Super Carrier Board is probably your best bet since the BASIC Stamp runs from the LM2940 VR on it. Current available to circuits would be less than 1A. Also, if the car is more than 5 years old you may have to consider filtering the power supply for noise generated by the engine. Most cars in the last 5 or so years are pretty clean supply-wise. I hope this helps. Take care.
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Chris Savage
Parallax Tech Support
Will you making your own board or will you be using a Parallax board ? If you will be using the Parallax board with the built in regulator you wont need to go to Radio Shack. It sounds like your project and the BS will be compatiable without having to add another power supply. You will just simply plug your cars 12vdc into the Parallax board and it will regulate the power for you. Please note that the 12vdc input to the board is usually considered the high end input. I believe that Parallax sells the Rpm counter that you need.
I haven't decided on my own board or a Parallax board but I like the idea that the BS board already has a regulator.
When you say "RPM counter", is that what the part is called? Or, are do you mean the Melexis 90217 Hall-Effect Sensor?
Yes, The hall effect Sensor would probably work fine but it requires a magnet. The Parallax web site has information regarding a Tachometer. Its free downloadable text. Go to the Parallax Home page and click on the education Tab at the top of the page, then click on Educational Main, click on Process Control, then scroll down to downloads at the bottom of the page and click on Process Control Text (PDF), and download. The Tachometer information is on page 114, Activity #6.
This information should help you make your decision on which way to go....
I would go with Chris Savage's reccomendations regarding the board...
Twisted Pair....
With regard to Chris's recommendation, I was given some BASIC stamps and boards a while back that I have not used. I would rather put those to use, before considering a purchase. Not only that, this device would have to be installed into an automobile premanently, so I would rather install older, less expense hardware.
I have, in my possession, a board with a BS2-SX, serial port and a breadboard on it, but not much else. There are no additional markings or identifying labels, and I can't find the equivalent on Parallax's site (its probably obsolete). I also have an Activity Board.(?)
Any way, I was thinking, in answering your question about which board I would use, I guess my answer would be both.
I was thinking I would use the breadboard to construct my circuit. It seems that I need a regulator for the 12v to 9V conversion and maybe a capacitor to level off the power (not sure yet, how to put it together).
I looked on RadioShack's website and they seem to have some regulators I can use. As for the capacitor, I am not sure if that is the best approach and how to size it.
I realize that I may be taking a little more difficult route by not going immediately to Chris's recommendation, but I would like to make this as much of a learning experience as possible.
It may work using that board. Another Tech here did some stress tests on input voltage and did exceed the maximum rating we list. That said, this was one module and if you damage yours due to over-voltage we won't be able to replace it under warranty. I believe the board you have is a Carrier Board which has no regulator leaving the BASIC Stamp to use its on-board regulator. You will be very limited in what you can draw from that for Vdd (5V) for other devices. Take care.
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Chris Savage
Parallax Tech Support
Thanks for your feedback.
The only devices I will have will be the optical reader (to determine the speedometer cable turns) and an LCD screen to display speed and mileage.
what do you think?
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Chris Savage
Parallax Tech Support
I just added up the part prices required to make a Basic Voltage Regulator circuit minus the PCB and Solder, Etc.... Get the Super Carrier Board. Part number, 27130....$19.95
Twisted Pair....
Thanks for the input, but does this solve my issues below...?
1) filter the power source - is this done by the regulator?
2) 12V to 5V regulator - looks like it
3) enough power for an LCD
4) regulated power from the BS2
Question 1) Filtering is usually done by use of Capacitors. Your cars Alternator and Distributor are prime sources for noise (Spikes Etc). In old cars that had points or breaker assembly's in them, a large capacitor was installed mainly on the distributor to remove noise from the cars radio. Even nearby radios in other cars and in some cases home radios could pick up these spikes. Newer vehicles have Electronic Ignition systems which reduce those spikes to a much lower level. Also, these same newer cars have mechanical Relays which produce spikes. A diode is placed across the power pins of these relays to help reduce those nasty Spikes. If your car has an onboard computer now, you may not have to do any filtering, but if you do, its not that big of a deal. Chris Savage speaks from experience about filtering older cars. I would follow his reccomendations just to be on the safe side. Remember, Chips are more sensitive to spikes than car radios....
Question 2) The board Regulator will drop the 12vdc down to 5vdc.
Question 3) More than likely you can run an LCD and a Sensor and maybe a little more but you haven't said what kind of hardware you will be using.
Question 4) If you use a board with a Regulator (27130), you with have two Regulators. One on the board and one on the chip....
In reference to my questions....
1) How do I size a capacitor for my project...? Although my car has an onboard computer, I would rather be safe and filter the power.
2) sounds like Sup. Carrier Board's regulator for the 12v to 5v should do the trick
3) I have a Scott Edward's LCD. I am also trying to figure out how I am going to encode the speedometer cable rotations. Still working on this one...
With respect to other hardware, I don't really have anything specific in mind. I am trying to replace the mechanical speedometer with a digital one (using a BS) plus odometer. Do you have any recommendations of things I might consider?
4) I am a little confused when you say 2 regulators. I see the one on the Sup. Carrier Board, but is there one embedded in the BS2 also?