Grab a Kit
1x 2V Solar Cell
1x Vibrating Motor
2x Big Paper Clip
2x Googly Eyes
6 inches of Magnet Wire
Hot Glue Gun
Helping Hand - (optional... but handy)
Sourcing Your Own Parts
We learned a few lessons as we were sourcing parts for our solar cockroach kits, which we are happy to share. This section will be most useful for those sourcing their own parts, if you are building from a kit, feel free to skip ahead.
Where to buy:
You can find these solar panels and motors all over the web. eBay has quite a few people selling them in bulk. You can use any cell you want, but the big factor is the size. The 2V rectangular cells work well in this case, though a small round cell would be fun to turn into a Solar Ladybug.
Motors can be bought in various sizes or shapes. Alternately, you can steal the vibrating motor out of an old cell phone or pager. This will save you $2.
You can also find individual parts for these kits on BrownDogGadgets.com, in case you're only missing one or two pieces. Feel free to contact us about discounts for educators or large orders.
What to look for
As mentioned on the parts list, you can use any sort of solar cell for this project, however, there are some things to keep in mind. While you can find heaps of different types of solar cells on the internet these days, not every cell is equal.
As we're using small motors, we're going to need a certain amount of power. I've found that most of the little vibrating motors you buy online need at least 1.5V and 30mA to trigger. We want our solar panel to go above and beyond that threshold. When solar panels are rated, they're given a rating at their max power level, which usually means noon on a sunny day. As these conditions don't exist all the time, we have to expect that our solar cell will usually be operating at a lower power level than what it's rated for.
The second thing to keep in mind is the size of the solar cell in relation to your motor. The bigger and heavier the cell, the stronger the motor you'll need to get it moving, the stronger the motor, the more power it will require... And on and on.
The key is to find a solar cell that is both small and has a good kick behind it. Salvaging solar cells from old garden lights has worked for us in the past, though often times they lack the current to get the motor started. The ones we prefer to use are some long and skinny 2V 50mA solar cells. They're cheap and easy to find online from quite a few places.
Small vibrating motors can be found everywhere, and you probably have several in your house right now, if not in your pocket. Common electronics such as cell phones, pagers, video game controllers, and electric toothbrushes all make use of these types of motor. You can easily scavenge broken or obsolete items for their motors, though you will find a large range of sizes. As with the solar panels, you have to hit the sweet spot between too large to turn on, and too small to move your roach.
Questions to ask your motor before you buy it:
1) Do you have soldering points?
You want a motor (and panel) either with wires, or large enough tabs to easily solder to. You don’t want to wind up with a motor you can’t connect to your panel.
2) Do you meet my power needs?
You need a motor that is rated to work at a very low voltage, aim for 1.5V. Most will do this just fine but we've occasionally run into some that need 2.5V or even 3V. Also remember that you need a DC motor, not AC.
3) Are you strong enough?
You can buy some really small vibrating motors, but they're not going to be strong enough move your roach. Usually the ones that are 15mm - 20mm long will do the trick.
4) Are you too expensive?
If you're paying more than $3 for a motor you're paying too much, especially when you figure in that shipping is never free. Just buy one off one of the websites above when you're buying some other hobby items. Find a couple of little projects on instructables and make an order. It saves on shipping.