Alvin, my old friend who co-authored Bebop BYTES Back and How Computers Do Math with me, recently sent me an email about an iPad app that really amazed him. In his own words:
iCircuit is an easy-to-use electronic circuit editor and simulator – the perfect tool for students, hobbyists, and engineers.
First of all you to capture a circuit using predefined devices including signal generators, voltage sources, and current sources; resistors, capacitors, and inductors; diodes and transistors (bipolar and field-effect); logic gates (AND, OR, NAND, NOR, XOR) and registers (JK and D-type flip-flops); digital-to-analog and analog-to-digital converters; manual SPST/SPDT switches and SPST/SPDT relays switches; and speakers, buzzers, and LEDs.
Using your finger you can place devices on the screen and wire up your circuit. You can also modify the values and semiconductor parameters associated with the components. The simulator is always running in the background, so as you add components you start seeing results, which is very cool.
You can excite the circuit by using the various signal sources that include DC, AC, sine wave, square wave, saw tooth, and pulse; also you can control each waveform's amplitude, shape, voltage offset, and so forth.
Similarly, you can use a virtual multimeter to measure the voltage or current at any point in the circuit. If you want to see how the values on signals change over time, you can display those signals using the built-in oscilloscope.
Overall this is a very nice tool that allows you to experiment and discover how circuits act. I only wish I had had this when my interest in electronics first surfaced. It would have saved a considerable amount of smoke :-)
At $9.99 this is great fun and tremendous value.
Cheers, Alvin
/3 
用户1406868 2012-10-22 15:58