lm358 dual single supply op amp

Single supply op amps, like the L358, have an output that can reach the negative supply voltage, but not the positive supply voltage. That makes them good for single supply (negative terminal of power source is 0V ground) voltage sources.

Comparator Circuits: Inverting and Non Inverting.

LM358 op amp wired as non inv and inverting comparator circuit learning electronics lesson 0020
LM358 op amp wired as non inv and inverting comparator circuit learning electronics lesson 0020

You can also use single supply op amps in dual supply circuits. That’s when you have 0V ground half way between a positive and negative voltage. Dual supply circuits often stay away from both + and – voltage extremes.


Assorted integrated circuits (ICs) kit. Included is the LM358 op amps and other commonly known ICs. I have previously covered some of the other ICs in YouTube videos. It is an Affiliate link ad that supports this channel.

Diagram shown above, and the video below, shows a couple LM358 comparator circuits. They also show the pin layout of the LM358 integrated circuit component, and some of it’s electrical limitations. Always consult the datasheet though for the most accurate information.

  • A comparator circuit has 2 inputs and an output.
    1. The output either goes as close to the positive supply voltage (high) as it can, or it gets as close to the negative supply voltage (low) as it can. The LM358 can get close to the negative supply at low current while low, but falls about a volt short from the positive supply when high.
    2. The op amp compares the voltage at the + (non inverting) input, and the – (inverting input).
      • The inputs just look at the voltage applied to them. They don’t let current through them, other than a very small amount of leakage.
    3. Non inverting comparator circuit has the changing signal voltage connected to the + input. While the reference voltage (usually fixed in one way or another) is connected to the – input.
    4. Inverting comparator circuit has the changing signal voltage connected to the – input. While the reference voltage (usually fixed in one way or another) is connected to the + input.
  • High output occurs when + input has a higher voltage than the – input.
  • Low output occurs when + input has a lower voltage than the – input.

Video:

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