Basic Stamp 1 Sound Bot

stavros

Goodmorning everyone,

Im considering building a simple bot that will produce sounds and make leds flash,using a BS1USB Board powered by a solar cell (something like a beam bot,but it will use the BS1).
Using a plain BS1 instead of the BS1USB board would save some space,but maybe its worth sacrificing a little bit of it for the usb interface.What do you think?

My main question is : Can the BS1USB board be powered by a solar cell? I have in mind this one http://www.solarbotics.com/products/scc3733/
It gives out 6.7V which is more than enough for the 5V that the BS1USB board requires.
I think I would have to use a 5V voltage regulator,a big capacitor(how big?maybe 2 1F 2.5V caps in series or is it too much?-http://www.solarbotics.com/electronic_components/capacitors/2/) and maybe some resistors?Anything else?

The design would be free form,so everything would be stuck or soldered on the board. Im totally inexperienced in electronics although I know basic soldering.
Some advice,guidance or even a quick schematic for the powering circuit would be very much appreciated.

If a solar cell cannot be used,then I think the only solution would be 4 AAA batteries.Are there any other kind of batteries that would give 5V or more and that would take significantly less space?
Thanks.

Mike Green

For a start, you'll need to use several of these in series. If you look at the voltage vs. current curves posted on the Solarbotics website, you'll see that the voltage given (6.7V) is the open circuit voltage, present when there's practically no current drawn. With any sort of load, the voltage drops quite a bit. It looks like you can count on 3V up to about 20mA (in full sunlight). I'd use 2 to 3 of these in series at least. You'll want a Shottky diode between the solar cells and the capacitors.

You want to use the BS1 module rather than the BS1USB because the BS1 has a voltage regulator and the BS1USB does not. The open circuit voltage of the solar cell will damage the BS1USB. The USB chip and the LEDs on the BS1USB also draw a fair amount of current.

Other options include using the solar cells to charge a set of 5 AAA NiMH rechargables. You wouldn't need the supercaps then (but you'd still need the Shottky diode). In that case, you'd probably want to use 3 to 4 solar cells since the batteries would need a higher voltage to charge properly.

stavros

Thanks very much Mike!
You said the BS1 Module has already got a voltage regulator.What are the specifications of it?

Mike Green

Look at the schematic. It's an LM2936. Just do a Google search to find the datasheet.

There's a link to the schematic from the product's webstore page. There are other useful links there as well.