| Electronics > Beginners |
| Basic Function Generator help |
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| dcbrown73:
To preface this, yes. I know this isn't a great function generator. I'm using it just to learn. In the circuit below. (image 1) Right now I'm just trying to learn (re use) the first part that creates the square wave. (image 2) I've set this up on my breadboard, but it does not create a square wave. It sits at a constant voltage. If the pot is turned all the way to the right, it sits at 25mv. If I turn it a maybe 25% of a turn, the op amp comes on and the output sits at 2v. Now, I've never read anything on how this is supposed to work. I was figuring that the pot would determine how quickly the 1uF cap charged and once it was charged, the amp would turn off and the cap would discharge and voltage would drop triggering the amp to come back up and recharge the cap thereby creating a sqaure wave. Well, in my recreation of the circuit. That isn't happening. Question 1. Am I mistaken that just trying to use the first part of the circuit will create a square wave? Question 2: If my assessment is incorrect. A) how is it supposed to work, and B) do I actually need more of the circuit to get a square wave to function? |
| Brumby:
I'm no Op-amp guru - but the answer to Q1 is: No, you are not mistaken. What I will ask, however, is what is your power supply setup...? |
| Jwillis:
Do you have a dual rail supply?I think It needs to oscillate between the positive and negative to work properly.I could be wrong to.Not an expert either. |
| Dabbot:
I just built the first stage up. Works for me. ~20Hz square wave. 9.6V supply. Using another LM324 to provide the ground. Can you supply pics of what you've built? |
| Brumby:
--- Quote from: Jwillis on August 04, 2019, 02:20:38 am ---Do you have a dual rail supply?I think It needs to oscillate between the positive and negative to work properly.I could be wrong to.Not an expert either. --- End quote --- Exactly. Which is why I asked the Op. |
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