Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

In what is now my only Robotics Lab class, the students used the voltage divider circuit completed by the other class for their quiz contest buzzers.

The other class used a node connected to the light emitting diode, one resistor connected to the ground, and two resistors which are connected to the high voltage, of different values, and one also including the switch. The key was in the proportion of the value of the resistors changing when the switch is open and when it is closed. Then the voltage to the LED would change from low (when it is open) to high (when it is closed).

The other class already had a difficulty in making the circuit work, which was apparently only due to their connections.

I also asked them to check using the logic probe instead of the voltmeter to find out what the voltage coming out of the LED was.

Using another set of values for the three resistors needed, the more recent class was able to make the switch work - by computation and not by trial and error like the earlier class.

The program of the more recent class was also able to work better than that of the earlier class, for which there was a large delay in lighting the diode to show who pressed first, despite the fact that all the pauses in their program were already taken out.

And the program of the earlier class, to make the loop run faster, had it such that one of the inputs will be checked first, then if it is "on" the second inputs (and the rest for when there are six buzzers) are not checked anymore. This priority, due to the slowed speed of their program, assures that in a split-second race between two buzzers, that biased buzzer will always win, and always had the diode light first.

Now they will change their program and their circuit to be able to handle six buzzers - slowly. Now I'm thinking if we could use another programmable chip for a second set of inputs, so that we would have a total of eleven - or maybe twelve.

Session 1865 wants to believe he is a whiz at all trades, but may be not. Class dismissed.