Can a Basic Stamp Run on 6v?

Bridger

Hey,
Sorry if this question is easily found in the documentation, but I am having trouble understanding some of the technical stuff. I have a contest I am entering, and would like to use the Basic Stamp as the "brain" of my car. However, we are limited to 4 1.5v batteries, or 6v. Would I be able to run my Basic Stamp Homework Board (which asks for a 9v battery) on 6v, and drive a continuous rotation servo with it? Thanks for the help, I am really tight on time and can't afford to spend too much time experimenting around. [noparse]:([/noparse]

Thank You,
Bridger Maxwell

tpw_man

The Basic Stamp HomeWork board can run on 6v if you have a way to connect the battery holder to the HomeWork Board. You can buy a 9v battery connector and hook up your batteries (or battery holder) to your connector. It should also work for driving a servo as well. I wish you luck in the competition!

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I am 1010, so be surprised!

cdesigns

Just a sussgestion, you can buy (5) AA 1.2v batteries rechargables Nihm (Energizer on Sam's club) each one holds 2500mAh wich it will be good to move that servo, and (5) batteries will be 6v even. The tricky part is making a 5 battery holder.



Post Edited (cdesigns) : 3/21/2008 8:43:14 PM GMT

Tracy Allen

It will be on the edge for using alkaline batteries. The voltage input at Vin should not be allowed to drop below 5.3 volts, which is the dropout voltage of the LM2936 voltage regulator on the homework board. That gives a cutoff per cell of 5.3/4 = 1.325 volts. Nominal 1.5 volt alkaline cells start out at 1.5 or 1.55 volts per cell, and if it were just the Stamp, it would take quite a while for the batteries to drop to that level. But my concern is the servos pulling slugs of current. The voltage will drop more at those instants and pretty fast if the servos are moving a lot of the time (in a car!?)

Another option with 4 cells, albeit pricey, is a set of Energizer e2 L91 1.5 volt lithium cells.



Terry of Hitt consulting has a five AA battery holder for sale that could be used for set of 5 NiMH AAs that as cdesigns suggested.

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Tracy Allen
www.emesystems.com

Bridger

Thanks for the help everyone. I will see if my school is willing to go for those batteries!

erco

You can run the Homework board off of 4 alkaline batteries IF you drop the voltage slightly with two silicon rectifier diodes (Radio Shack 1N4001-type) in series with your batteries. New AA alkaline batteries are ~1.60 volts. Each diode will reduce your voltage 0.5 - 0.7 volts, so start with two in series (polarity matters, unbanded end toward battery positive) and hook the banded end carefully and directly to your Homework board's Vdd (not Vin). Run your Stamp with NEW batteries and all your extra circuitry & sensors, and measure the voltage at Vdd, you want under 5.5 volts. If your particular diodes and added circuitry drop the Vdd voltage to 4.5 or less, you might want to carefully reduce to one diode and recheck your voltage at Vdd. You should add a filter cap (100 uF or so, watch polarity) from Vdd to ground (Vss).

Hook your servos directly to the battery +6 volts, not through the dropping diodes. Common negative ground (Vss) for everybody.

AA cell voltage will fade quickly and you'll have to change them a lot if you require consistent performance. Suggest you use C cells if possible, they'll last much longer. D cells are even better, but much heavier.

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·"If you build it, they will come."

Tracy Allen

Note that you can pick up exotic batteries far cheaper if you spend a little time looking online. The local hardware store will have low volume and a large markup!

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Tracy Allen
www.emesystems.com

StarMan

Bean has 5-AA battery holders on his web site:· http://www.hittconsulting.com/

Look in the "miscellaneous stuff" section.

Chris I.