Voltage sources for electronics basics

Voltage sources, and the accompanying current that they provide, are needed for all electronic circuits. This page only covers direct current (DC) voltage sources which have 2 terminals. One terminal for positive (usually red) and one terminal for negative (usually black). Negative terminal is declared as being the 0V reference point ground while the positive terminal is considered to be the supply voltage in relationship to ground.

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9V battery typical 0V reference ground location diagram by electronzap electronzapdotcom
9V battery typical 0V reference ground location diagram by electronzap electronzapdotcom
  • Battery – Voltage is the result of a potential of chemical reactions. Once a conductive enough path is connected, the chemical reactions take place as needed to move current. Forcing current into rechargeable batteries reverses the chemical changes and recharges the battery. Voltage goes down while discharging, and if rechargeable, goes up while recharging. You must always stay within the limits of any particular battery chemistry, so make sure to investigate them. Some common battery types are lithium ion, alkaline and Lead acid.
  • DC power supply – Takes the voltage and current from an outlet, or battery, and converts it into a usable voltage, often with the capability to limit current (by dropping voltage if need be). Voltage and maximum current may be fixed or adjustable.

There are a lot of voltage sources to choose from, so you need to research the specifics of whatever particular one(s) you are interested in.

I talk about using DC power supplies and lots of other topics in this video. Electronics course 1 Resistor component limiting current Ohms law and multimeter measurements

  • Ideal voltage source:  Impossible to achieve, but it would be a voltage source that can hold a steady voltage no matter how much current is demanded. The less internal resistance a voltage source has, the closer it comes to being an ideal voltage source.
2 battery split power supply diagram by electronzapdotcom of YouTube and Electronzap
2 battery split power supply diagram by electronzapdotcom of YouTube and Electronzap

Obtaining a different voltage/power from fixed voltage supplies.

  • Series batteries: Connecting batteries in series adds up their voltage. It is important to use batteries with the same voltage and capacity, and to make sure their voltages stay balanced.
  • Parallel batteries: Splits up the current demands, and thus can provide more current and total charge than a single battery. They absolutely must have about the same voltage when connected together, or high current will flow from the higher voltage battery to the lower voltage battery. After being connected together, they will automatically keep their voltages equal.
  • Non adjustable power supplies will need either a voltage buck and/or boost converter ,or a voltage regulator to get a different voltage.

Buck converters takes in a higher voltage/lower current and outputs a lower voltage/higher current.

Boost converters takes in a lower voltage/higher current and outputs a higher voltage/lower current.

There will be at least a little loss of power (voltage times current) though because no converter is 100% efficient.

Voltage regulators also output a lower voltage than the supply voltage. They don’t convert current and voltage, but instead they just basically add resistance as needed to set a voltage across the rest of the circuit. They get very hot, but they are very convenient when you just need low power for a lower voltage part of a circuit.



Not finding my voltage boosters, so here’s an affiliate link ad to some that are lower priced and have good reviews.

DC to DC boost converter LTC1871 module at almost 2 amp in 1A out demonstration by electronzap

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Related topics:

Other basic electronics topics that you should know before moving on to more advanced topics.

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.

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.

Other topics:

These pages are still being compiled.

Circuits covered more quickly series:

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