Make a reusable robot base / power suply in 5 easy steps
November 17, 2008
Every now and then I want to test a circuit or a new sensor or even some new idea for code but I don't have a starter kit or anything. While shopping for some robot parts I had an idea for a simple base that could be my equivalent of a starter kit, a power supply and a small robotic platform. This is what I came up with in 5 easy steps.
Buy a small breadboard, three 2xAAA battery holders and a couple of minature servo's, set up for continuous rotation. The battery holders are almost the same width as the breadboard.
Peel off the backing on the breadboard to expose the double sided tape backing. If your breadboard is a different brand then you may need to put on some double sided tape.
Read through this instruction carefully and note orientation of all parts before you stick them on as it is hard to peel them off again without wrecking the double sided tape. Stick on two of your battery holders, one either end with the solder lugs all on the same side. Notice that the servo drive shaft is not centre, make certain you put both servos the same way around. On the end closest to the servo drive shafts hot glue the third battery holder. Make sure the solder terminals of the battery holders are all on the same side. In the space in the centre put in a small piece of wood or plastic that you can later put some self tapping screws into.
Solder all your battery holders together in series, fit the batteries and screw a piece of thin wood or plastic into the centre piece. This is your skid pan, as well as stopping the batteries from falling out you can use hot glue to attach skids to level it out. I copied Fritz's idea from one of his little robots and used a cutdown table tennis ball.
Plug in you power supply components. I've used a low dropout regulator so that I get good regulation even if my batteries drop down to 5.5V. I'm using rechargeable batteries so I get 7.2V. Because this voltage is a bit high for servos I'll put 3 diodes in series with my battery for the servo supply. I don't recommend alkaline batteries or rechargable alkalines because they have a higher internal resistance and any voltage spikes will be bigger. You will also need to drop the voltage more for your servos as you will have a 9V supply.
That's it you now have a flexable, reuseable robot platform / power supply. The picture below is me using this as a power supply while I experiment with my MkII laser range finder. I've remove the wheels and skid pan so it sits flat. You can see the diodes used to drop my 7.2V down to under 6V for the servos.
Good luck and enjoy! :)