Make: Electronics Chp 2 Experiment 9

Experiment 9 “Time and Capacitors” is a soft introduction to the capacitor. The capacitor is a very interesting component and with it you can measure time. However, this is the first component that actually requires that you pay full attention to how it is placed on the bread board. Failure to check the polarity can result in the component exploding. As always eye protection should be worn, but especially when it comes to capacitors.

As far as measuring time. The circuit uses two tactile switches.  One switch will charge down the capacitor while the other will allow the capacitor to charge up. With a timer, i.e., smart phone or watch, you can observe how long it takes for the capacitor to charge. During my run at this experiment it took the capacitor about 1 to 1.5 seconds to charge.


The actual science behind the capacitor, or simply put,  the beauty of its function can be realized by the understanding of the RC network; of which Mr Platt provides a great over view. Most college text books get down in the weeds on this topic because it’s such a an important concept. However, what is given here is definitely sufficient for the beginner.

Moreover, this chapter continues to go deeper into the concept of the RC Network by teaching you how to graph the voltages during charging time. In addition to further tweaks to the circuit and experimental discovery.

Although it is not needed at this point, I would look into getting an oscilloscope. eBay has them for cheap if you’re on a budget. So definitely look into getting yourself one.

For what it’s worth. Electronics is basically all math. Hard math. Although, you probably won’t get any of that here (hard math). Don’t let this fact run you off if you’re math averse. Once you see how the math in electronics theory works hand in hand with the physical application – you’ll probably love math as much as I do….well maybe not that much.

Experiment 9 materials:

Bread board
9volt battery
2 Tactile switches
Generic LED
470 ohms, 1k, 10k Resistors
0.1 uf, 1 uf, 10 uf, 100 uf, 1000 uf Capacitors

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