Electronics is Fun

I got my cute little micro-controller board this week and immediately sat down to see what cool things it can do together with my circuits and components. It's an Arduino compatible micro board. There's a lot hype over these micro-controller boards, and rightfully so because of the many exciting possibilities of what you can do with your circuits. The micro-controller will be your interface to your computer, as it can accept analog and digital inputs and can be programmed through the open-source Arduino IDE (Interface Drive Electronics). It connects to the computer through USB. All you need is some little skills in programming in C language, and it's open to the world of many exciting possibilities. For the newbies in programming, don't lose heart because it's not really difficult to learn. You'll actually find it fun to learn. Arduino Compatible Micro Board   So what can a micro-controller really do? The fact that you can connect it your computer is a

Current source programs an output current as defined by the user, regardless of the load resistance. We know that when load resistance is larger, the voltage across it also increases. An ideal source would maintain a constant amount of current even if the load resistance changes, or in other words even if the output voltage changes. Such behavior describes a very good current source that has high output impedance. Remember, the output voltage changes, but very little or no change in output current. That means high output resistance or impedance. We use the term impedance when dealing with changes. Howland circuit in the figure is a classic current source circuit.   When R 1 is made equal to R 2 , R F equal to R 3,  the output current is given by V IN /R 1 where V IN is V 1 minus V 2 . A simple implementation is grounding V 2 and taking V 1 as the V IN . Figure 1 Basic Howland Current Source This circuit is such a clever manipulation of the op amp, such