Voltage Regulator Basics

Voltage regulators set a lower voltage than the supply voltage across a load. All of that extra supply voltage builds up across the voltage regulator. Therefore, that is power that is lost in the form of waste heat.  So, for higher demand loads, you are probably better off with a buck converter.

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If you just want to light an LED at a steady five volts while the higher supply voltage changes, then you could use the 78L05 to set 5V across the LED and it’s protective resistor. The 78L05 is a smaller version of the 7805 integrated circuit.

Video below goes live at 6AM CST 17 May 2023

1. 7800 or 78xx is a series of integrated circuits that outputs a positive voltage in relationship to 0V ground which is powered by a higher positive supply voltage. The 7900 series voltage regulator ICs output a negative voltage in relationship to ground from a more negative supply voltage. It’s good to have the supply voltage at least 2V more positive (or negative for 7900 series IC) than the voltage regulator’s output voltage.
2. The last 2 numbers of the 7800 series (and 7900 series IC) part number, is the voltage that will be output. The supply voltage should be at least 2V higher (or lower for 7900) than that.
   • 7805 outputs 5V. 78L05 is a smaller version that can’t provide near as much power.
   • 7809 outputs 9V. 78L09 is a smaller version that can’t provide near as much power.
   • 7812 outputs 12V. 78L12 is a smaller version that can’t provide near as much power.

Good topics to check out next:

List of Miscellaneous Integrated Circuits and Modules

Boost converter unit or module

Buck converter unit or module

Ferrule connector

Bipolar Junction Transistor basics – BJTs

NPN BJT switch circuit

PNP BJT switch circuit

555 timer IC basics

Op Amp Basics – Operational Amplifier

LED on when it is dark circuit using PNP BJT LDR – 2N3906 and Light Dependent Resistor

Light controlled NPN BJT switch – LDR high and low side

2N2222 TO-92 datasheet google search difficulties – NPN BJT 2N2222A PN2222A P2N2222A

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