Connecting resistors in series does a few things.
- Increases resistance
- Divides voltage
- Spreads out heat dissipation
Series resistors just add up each of their resistance, which becomes the total resistance. In the diagram below, we have three 1,000Ω resistors in series. So together they have a total of 3,000 ohms of resistance.
Series components always split up/divide/drop voltage from the power supply unless they have 0Ω of resistance.
The series resistors divide up whatever voltage is given to them based on their percentage of the series circuit resistance.
Equal value resistors are easy to calculate. Two equal value series resistors will have half the supply voltage across each of them.
Three equal value resistors connected in series as a voltage divider will have 1/3 of the supply voltage across each of them.
Power sharing – Heat generation/dissipation
The diagram in the last section above shows how two series 100Ω resistors with 5 volts across them (2.5V each) will both pass the same amount of current (0.025A or 25mA) as a 200Ω resistor with 5V across it . The wattage of each component is the voltage across it times the current through it.
Using a single 200Ω resistor with 5V across it will also pass 0.025A, and 0.025A x 5V = 0.125W. It will be twice as hot as either of the two series 100Ω resistors which will split the power dissipation. 2.5V x 0.025A = 0.0625W for each of the two series 100 ohm resistors.
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Other basic electronics topics that you should know before moving on to more advanced topics.
- Electronic component appearance and schematics – Commonly used through hole versions
- Electronic circuit basics
- Voltage sources for electronics basics
- Multimeter measuring voltage
- Resistor component – Learning electronics resistors
- Light Emitting Diodes – Indicator LEDs
- LED circuit -Lighting a Light Emitting Diode
- Resistor limiting current – Ohms law
- Multimeter measuring current
- Wattage – Electrical Power unit
- Resistors connected in parallel
- Series resistors
- Voltage divider – Setting a fractional voltage
- Resistor color code
- Diode – Rectifier
- Trimpot – Trimmer potentiometer – Voltage divider – Variable resistor
- Capacitor component
- Capacitor RC time constant
- Voltage ramp Demonstrated using a capacitor.
- LM334 three terminal adjustable current source not a common component. I use for an easy current source in many circuits.
- Switch NOT logic gate – digital signal inverter
- Switch OR gate – LED circuit
- Switch AND gate – LED circuit
- Switch based NAND logic gate – LED demonstration circuit
555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.
- 555 Timer IC This particulars of this integrated circuit covered on this page make a lot more sense after you study the basic circuits that follow.
- 555 timer bistable mode – Flip flip basic circuit
- 555 timer monostable mode – One shot
- 555 timer astable multivibrator mode – Flashing LEDs
- 555 timer schmitt trigger logic inverter – NOT gate
- 555 timer LDR controlled astable multivibrator mode LED flasher circuit
- 555 timer – Buzzer output – Astable multivibrator mode – Light dependent resistor LDR controlled circuit
Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.
- NPN BJT switch circuit – Bipolar Junction Transistor – 2N3904
- PNP BJT switch – Bipolar Junction Transistor – 2N3906
- NPN BJT emitter follower circuit – transferring a voltage minus a diode drop
- PNP BJT emitter follower circuit – Transferring weak signal voltage with a diode voltage shift
- Bipolar Junction Transistor BJT voltage follower circuit improved to eliminate base emitter diode shift
- NPN BJT current source – Bipolar Junction Transistor – 2N3904
- PNP BJT current source – Bipolar Junction Transistor – 2N3906
- Schmitt trigger – NPN BJT
- Zener diode component – voltage reference – regulator
- Voltage doubler circuit fragment- Capacitor charge pump – Some V loss
- 7805 5V positive voltage regulator IC
- Battery voltage state of charge SOC – From fully charged to discharged
These pages are still being compiled.
Circuits covered more quickly series:
- Brief fixed resistor voltage divider circuit
- Brief trimmer potentiometer trimpot variable resistor voltage divider circuit fragment
- Brief NTC thermistor voltage divider circuit