Page 6 operational amplifier op amp circuits

Op amps and comparators are the main focus of this page. The particular component (part number) you need to use will depend on the demands of the circuit you are building as they each have their own strengths and weaknesses.

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Op amp comparator plus non inverting with voltage follower basic circuit schematic diagram by electronzap electronzapdotcom
Op amp comparator plus non inverting with voltage follower basic circuit schematic diagram by electronzap electronzapdotcom

Key topics to learn about:

Info here is not guaranteed to be accurate. Always consult the component’s datasheet or more authoritative informational sources.

  • Common op amps and comparators with varying properties that should be studied. Listed in no particular order. They typically have LM or uA in front of them depending on manufacturer: 741 – 358 -393 –
  • Output.
  • Non inverting input. (+)
  • Inverting input. (-)

    IC output voltage range illustrated for dual split supply single and rail to rail diagram by electronzap electronzapdotcom
    IC output voltage range illustrated for dual split supply single and rail to rail diagram by electronzap electronzapdotcom
  • Dual supply (outputs short of supply voltages)
  • Single supply (outputs to negative/ground supply voltage)
  • Rail to Rail (outputs to both supply voltages)
  • Open collector/drain (output is either “off” or connected to ground)
  • Inputs just look at voltage. They leak a very small amount of current though, so very weak signals may need a higher impedance input op amp/comparator IC.

Non inverting single supply op amp comparator

Single supply op amp comparator circuit schematic diagram by electronzap
Single supply op amp comparator circuit schematic diagram by electronzap



White version of the oscilloscope that I use in many of my recent videos.

LM358 op amp non inverting comparator single supply circuit electronics how to tutorial

Inverting op amp comparator:

Diagram below looks like the one above, but the inverting (-) input and non inverting (+) input locations are swapped. It is always important to pay close attention to which input is above the other in the schematic.

Inverting op amp comparator using single supply LM358 circuit schematic diagram by electronzap
Inverting op amp comparator using single supply LM358 circuit schematic diagram by electronzap



Screwdriver set that I use in my videos.

Inverting comparator circuit using op amp LM358 single supply schematic and breadboard tutorial


Voltage followers take the input voltage and output the same voltage. The power provided to the load in this case is provided by the op amp (which gets it’s power from the power supply) so that a weak signal does not lose it’s voltage.

Single supply op amp voltage follower using LM358 IC schematic diagram by electronzap
Single supply op amp voltage follower using LM358 IC schematic diagram by electronzap



Power supply I use in my videos.

Op amp voltage follower using LM358 trimpot and LEDs electronics demonstration circuit

Light Dependent Resistor LDR LED dimmer circuit schematic by electronzap
Light Dependent Resistor LDR LED dimmer circuit schematic by electronzap



The ad above is where I got my LCR meter. It is not a replacement for a multimeter, but is a nice additional meter for getting more info about inductor, capacitor and resistor components than you can get from a standard multimeter.

Light Dependent Resistor LDR photoresistor measured with LCR meter and adjustable LED brightness

Light dependent resistor controled LM358 single supply op amp comparator circuit schematic diagram by electronzap
Light dependent resistor controled LM358 single supply op amp comparator circuit schematic diagram by electronzap



Kit that has everything you need to learn basic electronics and Arduino.

Light Dependent Resistor LDR photoresistor measured with LCR meter and adjustable LED brightness



My 74LS00 series IC kit (assuming they haven’t changed it at all)

Active buzzer low light alarm using LDR and LM358 single supply op amp circuit schematic diagram by electronzap
Active buzzer low light alarm using LDR and LM358 single supply op amp circuit schematic diagram by electronzap

Active buzzer low light alarm made with LM358 op amp comparator with LDR and 2N3904 NPN BJT circuit


5mA current source using LM358 single supply op amp circuit schematic diagram by electronzap
5mA current source using LM358 single supply op amp circuit schematic diagram by electronzap

5mA current source using single supply op amp LM358 circuit



74HC00 kit that is similar to mine, which isn’t available anymore. List of included IC’s is shown in the images.


Op amp voltage gain of 2 using single supply LM358 schematic diagram by electronzap.
Op amp voltage gain of 2 using single supply LM358 schematic diagram by electronzap.

Voltage gain of 2 using LM350 single supply op amp electronics circuit by electronzap



4000 series IC kit I have (assuming they don’t changed part numbers)

LM393 non inverting comparator demonstration circuit pin layout and schematic diagram by electronzap
LM393 non inverting comparator demonstration circuit pin layout and schematic diagram by electronzap

LM393 open collector non inverting comparator electronics circuit how to DIY tutorial by electronzap

Zener versus resistor voltage divider with changing supply voltage by electronzap electronics

OK versus low supply voltage indicator LEDs circuit using LM358 single supply op amp inverting comparator diagram by electronzap
OK versus low supply voltage indicator LEDs circuit using LM358 single supply op amp inverting comparator diagram by electronzap

OK versus low power source voltage indicator LEDs circuit with LM358 single supply op amp comparator

Op amp LM358 low versus OK supply voltage indicator LEDs with schmitt trigger output circuit
Op amp LM358 low versus OK supply voltage indicator LEDs with schmitt trigger output circuit

LM358 op amp low versus OK supply voltage indicator LEDs with schmitt trigger output electronics how

Single supply op amp astable multivibrator circuit flashing an LED schematic diagram by electronzap
Single supply op amp astable multivibrator circuit flashing an LED schematic diagram by electronzap

Single supply op amp LM358 astable multivibrator circuit with flashing LED demonstration circuit

Other pages in the short videos with diagrams series



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