# Fixing “Errors” in a electric circuit

This week we are having a exploratorium at my high school. We wanted to make an electric circuit, where the contestants have to find the three errors in the circuit. These errors is errors that we have made on purpose, but our problem is that we do not know which errors we should make.

Here is a diagram of our cicuit:

The three boxes that say "Fejl 1", "Fejl 2" og "Fejl 3" is the potential errors. It is in these three boxes we have to make errors the contestants should solve.

These errors have to go in a difficulty in order from easy to hard, being "Fejl 1" the easiest and "Fejl 3" the hardest.

We have thought of putting in a diode that went the wrong way, so they had to figure out that was the error and then turn it the other way around.

I now this may be a vague question, but I really do need your help, and all help will be appreciated.

• Just an \$0.02, this is not to dissuade you from your present approach. There is another neat class of Olympiad problems. You state that there is a black box, which has lights and switches on the outside. You define the behavior (e.g. when switch 3 closed, lights 2 and 4 are on). You say that inside the box there can be only certain types of components (e.g. wires, resistors, diodes, relays). Then you ask: "what's the circuit in the black box?" – Nick Alexeev Oct 7 '13 at 19:29
• Th first "fejl" I see is creating a circuit with no definition of what the circuit is meant to do. – The Photon Oct 7 '13 at 21:18
• Is the "error" supposed to act like an open circuit? How are the contestants supposed to prove that they "found the error"? Are they supposed to "fix" it? If so, what tools are they allowed to use? For example, are they allowed to open the boxes? – Joel Reyes Noche Oct 8 '13 at 0:44
• Just to make clear, these "fejl" boxes is not literally boxes, they are only drawed as boxes because it would be easier to understand. And just to make sure, "fejl" is a danish word which means error or mistake. So we need to make these errors so difficult that they can be solved by secondary school pupils without any prior electronic experience. An example on this could be that the resistor was too big, and there for the light bulp – Andreas Drivsholm Oct 8 '13 at 6:33
• If the black box is anything but a wire, it's an error. The only thing thing this circuit seems to be supposed to do is to light up three bulbs. Therefore no other components are needed, and having them would be a flaw. Any three components will do for the boxes. My (very late) suggestion for the third error is a forward biased diode, 2nd error a moderately large resistor, and 1st error a capacitor or open switch. – Oskar Skog Apr 2 '17 at 18:21