All was good in the land... until someone in China decided to stop making the little 1.5V solar cells AND the very efficient little motors which were the backbone of our vibrobot. Sadness fell on many a basement workshop. Little motors all over the world stopped vibrating.
Well after a bit of searching replacements were found! A better, and slightly more cockroach sized, solar cell was discovered and tested. A more powerful and flexible motor was bought. Now all those Solar Cockroach lovers out there can get back to making what they love: lead solder covered children's toys.
In this instructable I'll be showing you how to put together a Solar Cockroach. As stated above it's a small vibrobot that uses a solar cell to power a little vibrating motor. It's easy to construct and makes a great gift. How easy is it? I had my neighbor's 13 year old son put one together, and he had never soldered before.
Time: 15-30 minutes
Step 1: What You Need
1x 2V Solar Cell
1x Vibrating Pager Motor
1X Resistor or diode, or other bits of scrap wire.
2x Big Paper Clip
2x Googly Eyes
Hot Glue Gun
Helping Hand - (Optional, but really... handy)
Where to buy:
You can find these 2V solar cells all over the net. eBay has quite a few people selling them in bulk. You can really use any cell you want, but the big factor is the size. The 2V work well in this case though a small round cell would be fun to turn into a Solar Ladybug.
You can buy the vibrating motors all over the web. They come in various sizes or shapes. If you have an old cell phone or pager you can steal the vibrating motor out of it. This will save you $2.
I sell completed Cockroaches as well as kits on my website, BrownDogGadgets. I also have a variety of solar cells and vibrating motors if you're in the need.
As I said above, you can easily buy or salvage most of these parts.
*** Update. By request I've put together a non soldering version of this kit. It uses laser cut parts which you paint and pop together. Suitable for younger kids.
Step 2: Solar Cells
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 little 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. Now if we were using batteries we could just find a battery that has those exact specifications, but as we're using solar we have to go above and beyond. 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 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 me in the past, though often times they lack the current to get the motor started. The ones I 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.
Step 3: Motors
As they're common enough you can salvage them from old cell phones and pagers. The only downside is that they can have a large range of power, and some might not be strong enough to meet your needs.
If you need to buy them look online. I sell them on my website, and so do such sites like All-Electronics and Electronic Goldmine. They can be found for between $1-2. No matter where you get them, just don't get them at Radio Shack. They're a total rip-off.
In the picture you'll see lots of types of motors. There are countless types, but these are some common ones I've picked up for salvaged.
When buying here is what you must keep in mind:
1) Does it have soldering tabs?
You want a motor with tabs, not wire wires. If you get one with wires you'll have no place to solder to.
2) Does it meet my power needs?
You need one that is rated to work at a very low voltage, 1.5V should be your aim. Most will do this just fine but I've occasionally run into some that need 2.5V or even 3V.
3) Is it strong enough?
You can buy some really small vibrating motors, but they're not going to be strong enough move your roach. Ones that are usually 15mm - 20mm long seem to do the trick.
4) Did I just buy a pancake style vibrating motor?
Goodness I hope not. While they work great for certain things, they don't work well for this project.
5) Did I pay too much?
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.
Step 4: Cut the resistor
Go as close to the middle as possible.
Throw away the middle and keep the legs.
Step 5: Bend the legs
Because of the type of tabs I have on my motor I need to bend one of my wires. To do this I just take some pliers, grip the very end of one of the resistor legs, and bend at a 90 degree angle.
I only do this on one.
Again, if you've got regular solder tabs you won't need to do this.
Step 6: Solder the motor
Now before you start to solder you must keep in mind that these are small motors and can easily melt if you "over" solder them. You want to put your iron on for a count of three, quickly apply the solder, and pull away. You don't need much solder to make a good connection and I'd hate to see you waste your $2 motor.
First, put the motor into a clip so that the rotating end is inside the clip, and the soldering bits are sticking out.
Second, put the resistor leg in the other clip. Line up the two so they're touching.
Because I'm using a nonstandard motor my soldering point is the round metal bit on the rear of the motor. This is where I press up my little 90 degree bend bit.
(You can see me soldering a more "standard" motor in my old guide. It's really not complicated.)
Third, line up the solder on one side of the wire next to your solder point.. Then put the soldering iron a little ways up the wire. The heat will flow down and this helps prevent you from overheating and destroying the motor.
The solder should start to flow rather quickly, within a 5 or 6 seconds. If it doesn't, pull away. You want to quickly add solder and get out of there as soon as possible!
Fourth, you'll add the second resistor leg. On a standard vibrating motor you'd just add it to the other little tab, but this is where I like my non-standard motor better. My second tab is the entire outer shell.
So for me I just line up the second wire so it is touching the outer metal shell and then solder the wire on. This allows me more freedom in tight situations.
At this point you should have a motor with two short wires attached to it. Before moving on you should really test out your motor. The most simple way is to just grab a battery and touch the two legs to the ends (a small flat coin battery works best). If the motor starts to vibrate then you're golden, if not then you may have melted you motor. Or you have a bad battery.
Step 7: Solder the solar cell
Just lay the solar cell down and align the wires so that they touch the cell's solder points. It does not matter which wires goes to the positive point and which goes to the negative point.
You'll also want to determine how far you want the motor to stick out of your roach. I like keeping my motor under the solar cell, so they're not sticking out the rear, which means that I don't use the full length of the wire.
Place your soldering iron tip so it is touching both the wire and the solder point, while keeping your solder on the other side. You don't need to go overboard with solder, just bit will do.
Repeat this on the other side.
Once dry, turn your solar cell over just to make sure everything is sticking. If you'd like you can go outside and test it out. Under bright sun your motor should turn.
Step 8: Cut the paper clips
You want to make two sets of even legs.
Just watch out, these things do tend to fly around when you cut them.
Step 9: Glue the legs
Use your "Helping Hand" again to hold on set of legs.
In one hand grip your hot glue gun, in the other hold the second set of legs.
Now liberally apply hot glue.
Wait for it to melt.
I personally like to have the front legs and an angle so that the back of my roach is higher than the front of my roach. How you do things is up to you.
Step 10: Apply the anntena
Place it in the front middle of your solar cell. It helps to hold onto it.
Apply some hot glue.
Wait for it to dry.
Step 11: Apply eyes
To do this I first apply a little bit of hot glue to the bottom on my solar cell, to the right or left of the antenna.
I then take one eye and smear some glue onto it and move it around to the front.
This way the eye is looking forward yet is really glued to the bottom on the solar cell.
Do this for the second eye as well.
Step 12: Enjoy!
Take it outside and see it wiggle. Remember you're going to need either some strong sun or a really insanely strong light. When I made the video of a bunch of them on a table it was around 2 on a decently sunny day. When a cloud blocked out the sun they stopped working.
Once you get the hang of it these things are really quick to make. You can probably speed make one in 10-15 minutes. My 13 year old neighbor boy made one in 20 minutes his first time.
I hope this guide and video were helpful. These things are fun to make and are an awesome "first robot" project for kids.
If you'd like a kit or just some random parts you can get them off my website, BrownDogGadgets.com, or off any number of other electrical parts websites. Though keep in mind that 34% of all BrownDogGadgets sales go into doggie treats for one lazy labrador.
*** Update: A non soldering version of the project is now available. It's much better for younger Makers and students.