Are you asking "What is the voltage and current" necessary for the BASIC Stamp?· If so, All BASIC Stamps require 5v and range from 1mA to 60mA in order to run.
Umm, you REALLY should NOT try to use a resistive voltage divider to control voltage to the Stamp. That's what Linear Regulators are for. The BS2's load (current pull) varies quite a lot depending on the I/O pins being driven. If the Vdd goes above 5.5 volts you'll fry the BS2, and if it goes below 4.5 you'll 'brown-out' reset the BS2.
The on-chip regulator works, if you drive 'Vin' with 7 to 16 volts DC.
I wouldn't recommend that (car electrical systems are very harsh) -- you should run it through a voltage regulator (we like the LM2940) to provide 5 volts to the BASIC Stamp and the rest of your circuit. You'll also want plenty of filtering on the 5-volt supply.
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Well, you COULD use the 12 volts from a car battery. You definitely should add a small (1 uF ceramic) and a large (20 uF electrolytic) capacitors in parallel to try to filter some of the noise on a car 12-volt line. This assumes the car battery is IN the car, of course.
What Jon means by 'harsh' above is that a car's 12-volt line, when the engine is running, has all kinds of noise spikes on it. First of all, the 12-volt line varies from 10 volts (when cranking the motor) to 13 volts or more (when the alternator is charging the battery).
An additional issue is what are you going to use the BS2 for? Typically, people want to light some LED's, maybe switch some relays. These things take more power than the on-module regulator can supply. Thus it's a very good idea to start out with some board (like the Parallax Super Proto board) that already has a regulator, space for the BS2, and some space for additional components. It's only $20.00 or so, and simplifies the initial project build cycle a lot.
You can do anything you want ... but I would personally never connect a BASIC Stamp to a car battery (that is in a car, that is) -- and I don't have to pay for BASIC Stamps! It's not the voltage that is the problem, it's all the garbage the rest of the car's electrical system puts on it. Still, when using a 12-volt wall-wart, I don't use Vin. The regulator on the BASIC Stamp module really doesn't do much more than the module itself and a few LEDs. Make your life easy: build a simple LM2940 regulator circuit like we use on all of our development boards.
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Dave
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Dave Andreae
Tech Support
dandreae@parallax.com
[noparse][[/noparse]url]Http://www.parallax.com[noparse][[/noparse]/url]
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·· If you're talking about the Stamp Stack, that was manufactured by HVW Technology so they may have the specs.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
The on-chip regulator works, if you drive 'Vin' with 7 to 16 volts DC.
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Jon Williams
Applications Engineer, Parallax
What Jon means by 'harsh' above is that a car's 12-volt line, when the engine is running, has all kinds of noise spikes on it. First of all, the 12-volt line varies from 10 volts (when cranking the motor) to 13 volts or more (when the alternator is charging the battery).
An additional issue is what are you going to use the BS2 for? Typically, people want to light some LED's, maybe switch some relays. These things take more power than the on-module regulator can supply. Thus it's a very good idea to start out with some board (like the Parallax Super Proto board) that already has a regulator, space for the BS2, and some space for additional components. It's only $20.00 or so, and simplifies the initial project build cycle a lot.
See: http://www.parallax.com/detail.asp?product_id=27130
You definitely should be able to connect this to your car battery. Jon might want to confirm this.
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Jon Williams
Applications Engineer, Parallax