op-amp square wave oscillator

Thread Starter

Exjay

Joined Nov 19, 2015
94
Please I need a expert help here or any experience hobbyist. I built this circuit and connected the output to LED to blink. Unfortunately, the LED did not blink but only on, so I begin to change the value of C1 & R4 to see the LED blink. At a particular value of C1 & R4, I coupled a capacitor to the LED from the output the LED blinks but was very faint. I coupled the capacitor since it passes time-varying signal and I also don't have an oscillator. What am asking now is that, is the circuit oscillating very fast that is not feasible to the eye?
 

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AlbertHall

Joined Jun 4, 2014
11,504
What op-amp are you using?
What supply voltage are you using?
You connected the LED between the amplifier output and which supply rail?
What value resistor did you have in series with the LED?
 

LesJones

Joined Jan 8, 2017
3,494
The LED is probably clamping the output of the op amp preventing it from oscillating. Put a resistor in series with the LED with a value that will limit the current to 5 mA. We can't tell you the value as you have not answered three of the four questions in post #4

Les.
 

Thread Starter

Exjay

Joined Nov 19, 2015
94
The LED is probably clamping the output of the op amp preventing it from oscillating. Put a resistor in series with the LED with a value that will limit the current to 5 mA. We can't tell you the value as you have not answered three of the four questions in post #4

Les.
Thanks. Truly the LED is clamping the voltage. When I connected a resistor in series with the LED it blinks
 

AnalogKid

Joined Aug 1, 2013
9,353
Truly the LED is clamping the voltage. When I connected a resistor in series with the LED it blinks
WHAT resistor?
WHAT voltage?
Re-read posts #2, #4, and #6.

The 741 has two power supply pins. What are each one of them connected to?

There is no LED in the image you posted. Please show us *your* schematic, one that shows all components and connections.
Also, increase the 1K resistor 10 10K to make the blinking easier to see.

ak
 
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