Op Amp LM358 LED flasher oscillator

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SUMMARY

The discussion centers on troubleshooting an LED flasher circuit using the LM358 operational amplifier. Users reported difficulties in getting the circuit to function correctly, particularly with resistor values and connections. The omission of a 100k resistor between the V+ and non-inverting input was highlighted as a potential issue, especially in circuits without split power and a center ground. Proper wiring and resistor values are crucial for the circuit's operation.

PREREQUISITES
  • Understanding of operational amplifiers, specifically the LM358 model.
  • Basic knowledge of electronic circuit design and breadboarding techniques.
  • Familiarity with resistor values and their impact on circuit behavior.
  • Knowledge of power supply configurations, including split power and ground references.
NEXT STEPS
  • Research the function and configuration of the LM358 operational amplifier.
  • Learn about resistor value selection in oscillator circuits.
  • Study the principles of non-inverting and inverting inputs in op-amp circuits.
  • Explore common LED flasher circuit designs and their troubleshooting techniques.
USEFUL FOR

Electronics enthusiasts, hobbyists building LED circuits, and engineers troubleshooting operational amplifier applications.

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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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.
 
That is what I saw, missing resistor.
 

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