Teaching basic electricity - part 3.
The last two issues have discussed ideas to help teach basic electrical concepts. This month's edition continues the theme and highlights some more examples of using a scope to teach electricity.
When I teach basic electricity, my students build and test circuits as discussed in last month's issue. Figure 1 shows a three-bulb series circuit like that shown last month with a PICO scope connected to show each voltage drop and the current flow. While not earth-shattering, this set up does provide a good visual of how current remains constant in the circuit relative to the voltage drops.
Figure 2 shows a turn signal circuit using an old 552 flasher unit connected to an 1157 and a 194 bulb wired in an alternating-flash circuit found on many older GM products. In both figures 1 and 2, it is clearly visible that the bulbs require a small amount of time to heat up, which affects the current flow in the circuit.
Figures 3 and 4 show the current flow through two different types of windings. Figure 3 shows current flow through a generator field coil that has been removed from a generator. This type of demonstration is great when discussing electromagnetism and CEMF. Also, it's fun to toss small tools at a charged field coil to impress students with the strength of the magnetic field that is created. Figure 4 shows current flow through a fuel injector. This type of image is nice because it shows how the movement of the core affects the magnetic field.
Figures 5 and 6 show two different power window circuits. Figure 5 is a passenger window, and Figure 6 is the driver's side window with the auto up and down feature.
Figure 7 shows battery voltage and current during cranking and starting on a known-good vehicle. With this one capture, you can show battery, cranking motor, and generator condition. Figure 8 shows the same vehicle during extended cranking to perform a relative compression test.
More to come next month.