Op Amp LM358 LED flasher oscillator

In summary, the speaker has been attempting to test Op Amp LED flashing circuits from the internet on a breadboard, but none of them have worked so far. They have checked their wiring and tried different resistor values, but still cannot get the LED to flash. They have also noticed that some circuit diagrams on the internet do not include a 100k resistor between the positive supply and non-inverting input. The speaker is wondering why it is so difficult to get an LED flasher to work with an Op Amp and why some diagrams omit the 100k resistor.
  • #1
Amyniuo
6NMfl.jpg

I have tried many times testing some Op Amp LED flashing circuits on a breadboard from the internet. So far, none of them works. The photo above is one of my attempt using a
Ti IC chip LM358. I have double checked my wiring and swap the 100k with 10k and 56k resistors. what is the problem here? why it's so hard to get a led flasher working with an Op Amp? Also I notice some of the circuit diagrams in the internet don't have the left 100k resistor between v+ and non-inverting input. why is that?
 
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  • #2
Here is my copy of your pic.
CCT.jpg

So where's the fifth resistor and check the connections to the +ve input.

I think omitting the non-inv input via R to +ve supply may be needed because not using split power and centre ground. If you omit it here, when op goes low the inv input can never get lower than non-inv.
 
  • #3
That is what I saw, missing resistor.
 

What is an Op Amp LM358 LED flasher oscillator?

An Op Amp LM358 LED flasher oscillator is a type of electronic circuit that uses an operational amplifier (op-amp) to generate a periodic signal to flash an LED on and off. It is commonly used in electronic devices such as toys, alarms, and automotive turn signals.

How does an Op Amp LM358 LED flasher oscillator work?

The Op Amp LM358 LED flasher oscillator works by using an op-amp as a comparator to compare the input signal to a reference voltage. When the input signal rises above the reference voltage, the op-amp output switches to a high state, turning on the LED. As the input signal falls below the reference voltage, the op-amp output switches to a low state, turning off the LED. This process repeats, creating a flashing effect.

What are the main components of an Op Amp LM358 LED flasher oscillator?

The main components of an Op Amp LM358 LED flasher oscillator include an op-amp, resistors, capacitors, and an LED. The op-amp acts as a comparator, while the resistors and capacitors determine the frequency and duty cycle of the flashing signal. The LED serves as the output indicator.

Can I adjust the flashing speed of an Op Amp LM358 LED flasher oscillator?

Yes, the flashing speed of an Op Amp LM358 LED flasher oscillator can be adjusted by changing the values of the resistors and capacitors in the circuit. A larger capacitor or resistor will result in a slower flashing speed, while a smaller one will result in a faster flashing speed.

Are there any precautions to consider when using an Op Amp LM358 LED flasher oscillator?

Yes, there are a few precautions to consider when using an Op Amp LM358 LED flasher oscillator. It is important to use the correct power supply voltage, as using a higher voltage could damage the circuit. Additionally, it is important to not exceed the maximum current rating of the LED. Finally, care should be taken to ensure the correct polarity of the LED is connected.

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