Capacitors have 2 primary purposes in electronics.
- Store energy for temporary power. Supercapacitors are very large value capacitors that can actually power small loads for a relatively long time.
- Change voltage over time in order to be used as a signal.
Other pages of this series
- Page 1 Electronics learning for hobbyists and students
- Page 3 – 555 timer basic circuits
- Page 4 – Bipolar Junction Transistors BJTs basics
larger value capacitors are almost certainly polarized. That means one side needs to always be the more positively charged side while the other side if always the more negatively charged. Damage will occur if you reverse charge them. Generally speaking, polarized capacitors are black cylinders with a gray stripe and dashes on the negative side. The positive size also usually has a longer metal lead than the negative side.
Basic capacitor demonstration circuits
It takes time for a certain amount of current to fully charge or fully discharge a capacitor with a certain amount of capacitance. The LEDs in this circuit give you a way to help see current flowing into or out of a capacitor if you only press one button at a time.
Video below is a variation of the circuit above.
RC time constant
The time it takes a capacitor to charge/discharge through a resistor is called the RC time constant. One time constant (in seconds) is equal to the capacitance of the capacitor in farads (F), times the resistance of the resistor in ohms (Ω). It takes 5 of those time constants to go from fully discharged to fully charge, or from fully charged to fully discharged.
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A steady current into, or out of, a capacitor leads to a steady voltage change. Since it is a straight line working it’s way up or down when graphed, it is called a ramp.
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Affiliate link ad. Nice looking capacitor kit for those needing larger value capacitors.
- 007 Parallel components – Resistors – Light emitting diodes LEDS – Capacitors
- Series capacitors
- Voltage doubler circuit fragment- Capacitor charge pump – Some V loss
- 008 NPN Bipolar Junction Transistor BJT switch including capacitor timed fade off
- 009 PNP Bipolar Junction Transistor BJT switch including capacitor timed fade off
- Voltage across RC time constant resistor and capacitor
- 018 NPN BJT Schmitt trigger plus capacitor timed off circuits
- Information on this site is not guaranteed to be accurate. Always consult the manufacturer info/datasheet of parts you use. Research the proper safety precautions for everything you do.