Let's Make Robots!

Transistors -[Page 3] Switches, common or uncommon

[Added note: while I had intended to add more to this series of pages, to explain FETs (jfet, mosfet, etc.) and so on, I have decided at least for now to not do so. I realised I would just be "reinventing the wheel" as the saying goes, when there are already so many good books on the subject.

A (VERY) Simple "Robot" (if we can call it that.)

One of our members ask how he could build a robot but lacked parts, money, soldering iron and so on.

I decided I would try to come up with the simplest way a small "robot" car could be done without all those things.

He said he had an old car he could use, and that he had some motors and wires.

Without a soldering iron connections can be made by twisting wires together. It is not a good way, but will work for a little while. If your robot stops working check that the wires have not come loose.

LASERS - just a bit about them

Just a couple ideas for those who are set on experimenting with lasers.

FIRST and most important: Lasers are dangerous. I am not espousing that you do anything with lasers, as you can be blinded BEFORE YOU CAN BLINK, if you use lasers stronger than the common "keychain" laser pointers.

Radio Link for your robot to your computer (Cheaply).

          Some of you have noticed the small, low-priced transmitter-receiver pairs available, which seem quite nice for robotic links, robot to robot, or robot to controller or controlling computer.

Solar Charger for my robot

I have placed several solar cells on the top cover of my robot, Shrödinger.

I noticed that for various reasons such as shadows falling on some cells, or one side being closer to a light, that the cells did not charge at the same rates. Solar batteries do not work well if they are allowed to backfeed the current from one to another. Consequently, I used diodes in each string of two to block this backfeeding.


I have noticed several people using an H-bridge schematic (commonly circulated on the web) that will work, but if both inputs are high at the same time, can throw a short across the motor power supply.  As long as they never let that happen, these circuits will work, but I consider it unsafe. Since many people here have different levels of expertise in both hardware and software, it is better to use an arrangement that prevents accidentally shorting anything.

Getting SOUND from your Picaxe (Works with other controllers also).

WARNING:  If "techie-stuff" makes your head hurt, do not read the following. 

      (ha ha)


To make sound from your picaxe, the manual shows a 10 uF capacitor in series with a 40 ohm speaker.

This will work but gives a very low volume sound.