Let's Make Robots!

little 8 supplies

alright, so i've never actually built a robot before and all that, so i thought i'd look into starting with the little 8. however, none of the canadian/american online shops seem to carry either the 5V voltage regulator or the "bumper switches" mentioned in the materials. is there some other name for these, or some sort of acceptable substitute that can be found in one of the north american online stores? i checked the ones listed on the 'where to buy picaxe' page, and i'd rather not have to do the whole overseas shipping thing (for some reason it always turns out badly for me)

then again maybe i'm just being stupid and missing the listing in the stores.

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True, I've done that on some of my projects where even small switches were too big.  However, at approximately 2-3 USD I'd say follow the K.I.S.S. theory.  Keep It Simple Stupid.  Just make sure to press the switch a couple of times before buying to check how much pressure is needed to activate it.
robologist's picture

Instead of using a switch for a bumper sensor, a pretty sensitive one can be made with a bit of "piano wire" or guitar string with a couple other bits and some connected wiring. Many hardware stores have stiff wire that serves well in this capacity. Shown at the bottom of this pdf file.  Arrick robotics

 You can even have it as part of a spring too. Solarbotics      and again

You can also pick up those little switches that already have a metal bar across the switch.  They should be very easy to attatch whiskers to with a little dab of epoxy.  My description isn't very good so here is an example.  An SPDT (single pole dual throw) or SPST (single pole single throw) will both work.  Just make sure that if you get an SPDT that you hook the leads up the right way.  If you get it backwards it will just make the switch be in the "on" position until it bumps into something.  You can swap the leads back or swap the low and high values in your code.
Daniel's picture

Dan :)

hey i have lots of junk that i bet i could some of the stuff for the little 8 out of but i dont trust getting items over the internet. Is there any other place in canada ontario where i could get it>

P.S. i travel alot so i should be able to pick it up somewhere here

thank you guys so much! radio shack visit is definately in order. ahh, so excited to get this started.
thank you so much! radio shack visit is definately in order.
jka's picture

I took a look at Sparkfun, because I thought I saw them there:

http://www.sparkfun.com/commerce/product_info.php?products_id=107

Also, Solarbotics has another regulator than the 7805:

http://www.solarbotics.com/products/lm2937/

I haven't got any personal experience with this one, but it seems to be better than the 7805.

 

An, as CowGod writes, old retired hardware is a good source for components of all kinds.

 

 

TheCowGod's picture

Hi there. I'm surprised you had trouble finding those parts, especially online. The 7805 voltage regulator is a very common part -- if you're in the US, as it sounds that you are, any local Radio Shack should carry plenty of them (it's one of the few electronics components they still bother to carry).

The switch could be hard to find with those metal 'whiskers' attached. The part of the switch that actually activates is a small plastic button on the upper face of the black plastic body of the switch, and the metal 'whisker' just presses down on that when it bumps into something. You can see one of those switches glued into the front of my robot, Feivel:

12131

You should be able to find them in that form in online shops like Digikey or Mouser, and possibly even in a store like Radio Shack. I actually got that one in the picture (and two more) out of the old computer mouse that also became the body for my robot. They're on the circuit board under the mouse buttons and sometimes under the wheel too. A few seconds with a soldering iron and you can liberate two or three from the average mouse. As far as the feeler, you could always cut up an old credit card into thin strips and glue a strip to the switch so that it activates it when it runs into something. Just an idea. Good luck.

fritsl's picture

What a briliant reply, there, CowGod!

/ Fritsl