Page 2 capacitor basics – How to use in circuits for DIY beginners learning electronics

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 while.
  • Change voltage over time.

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Basic capacitor demonstration circuits

It takes a period of time of current flowing for a capacitor to fully charge or fully discharge. The LEDs in this circuit give you a way to help see when current is flowing into, or out of, a capacitor if you only press one button at a time.

Capacitor charge and discharge through resistor and LED circuit schematic diagram by electronzap electronzapdotcom
Capacitor charge and discharge through resistor and LED circuit schematic diagram by electronzap electronzapdotcom

Video below is a variation of the circuit above.

Quick capacitor charge and discharge through an LED circuit schematic to breadboard build

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.

Simple RC time constant charging capacitor at switch release circuit by electronzap electronzapdotcom
Simple RC time constant charging capacitor at switch release circuit by electronzap electronzapdotcom

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Quick RC time constant of charging capacitor schematic to breadboard build and oscilloscope

Simple discharging capacitor RC time constant circuit schematic diagram by electronzap electronzapdotcom
Simple discharging capacitor RC time constant circuit schematic diagram by electronzap electronzapdotcom

Affiliate link ad. Americans clicking this link help support the site at no extra cost to you! Kit that has the screwdriver I use in most of my videos.

Quick discharging capacitor RC time constant circuit schematic to breadboard build and oscilloscope

Voltage ramp

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.

Simple charging capacitor voltage ramp using constant current source schematic diagram by electronzap electronzapdotcom
Simple charging capacitor voltage ramp using constant current source schematic diagram by electronzap electronzapdotcom

Affiliate link ad. Looks like a really good kit to own if you need higher value capacitors.

Quick 1000uF capacitor voltage ramp using LM334 set at 1mA circuit schematic to breadboard build

Simple discharging capacitor voltage ramp circuit schematic by electronzap electronzapdotcom
Simple discharging capacitor voltage ramp circuit schematic by electronzap electronzapdotcom

Affiliate link ad. Nice looking capacitor kit for those needing larger value capacitors.

 

Quick discharging capacitor voltage ramp circuit schematic to breadboard build

Page 3 – 555 timer basic circuits



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  • 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.