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Hex Inverter OSC help.
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Circlotron:
The negative (or half rail point) of the power to your opamp must be grounded together with the other ground points on your circuit. Putting 9 volts straight from top to bottom of the opamp will kinda power it but the opamp input and output will have no earth reference so it will not operate very well at all.
elizark:

--- Quote from: Zero999 on January 10, 2019, 10:08:36 am ---
--- Quote from: elizark on January 10, 2019, 09:16:41 am ---
--- Quote from: Zero999 on January 10, 2019, 09:01:41 am ---Of course the op-amp must be powered to work.

The TL074 doesn't have enough output current drive to power a speaker. You need a power audio amplifier IC. The LM386 is better suited to the job.

--- End quote ---

I assumed that was the issue. Silly me! Even if I had powered the TL074 with +/- 9v would it not be enough?

https://www.eecs.tufts.edu/~dsculley/tutorial/opamps/opamps5.html

That link above is what I used to make the buffer. If I fed the buffer into another op amp and raised the gain using the equation from that link, would that drive enough current? The speaker I'm using now is from an old Panasonic cassette memo thing. I do plan on wiring a 1/4" jack to run it to a preamp, so would that eliminate the need for anything past the buffer? Sorry, I feel these are basic questions! I hope to learn a LOT from the community! :)

--- End quote ---
The TL074's output can't output enough current to drive an 8Ω speaker. Increasing the power supply voltage or the gain will not make any difference. You need an IC with a higher output current rating.

Look at the graph on the bottom right hand corner of page 21, figure 6, on the TL074 datasheet. It plots the maximum output voltage vs load in kΩ. With a 0.1kΩ load, or 100Ω, the output voltage is under 0.1V, so with an 8Ω speaker it will be virtually zero.
http://www.ti.com/lit/ds/symlink/tl072.pdf

--- End quote ---

The dreaded datasheet! Still a bit scared of those, but thank you so much! Definitely helped my fear there. SO much useful info on those graphs! :D
elizark:

--- Quote from: spec on January 10, 2019, 12:15:27 pm ---+  elizark

Attached is a schematic for a circuit, using the CD40106 and a couple of transistors, to generate an audio tone from 100Hz to 10KHz. If you have any questions just ask. :)

--- End quote ---

Hey spec! Thanks for this circuit! Might as well give it a try and try to learn as much as I can from it :D

To stop bumping this thread should I ask questions about it in PM?

Cheers!
elizark:

--- Quote from: Audioguru on January 10, 2019, 07:37:15 pm ---The simple oscillator using the CD40106 produces a squarewave output that sounds like a buzzer. Do you want that sound? For a synth you probably want many types of sounds so maybe an oscillator that produces a sinewave is better then it is easy to change to many different types of sounds.

--- End quote ---

Audioguru! Love the name :) Eventually I would like to build something like , but I have a ways to go to understand all that. For now, I'm just doing the small things and (trying to) learn hands on.
Zero999:

--- Quote from: elizark on January 10, 2019, 09:05:40 pm ---
--- Quote from: spec on January 10, 2019, 12:15:27 pm ---+  elizark

Attached is a schematic for a circuit, using the CD40106 and a couple of transistors, to generate an audio tone from 100Hz to 10KHz. If you have any questions just ask. :)

--- End quote ---

Hey spec! Thanks for this circuit! Might as well give it a try and try to learn as much as I can from it :D

To stop bumping this thread should I ask questions about it in PM?

Cheers!

--- End quote ---
The downside with private messages is no one else can help or learn.

One way to avoid cluttering up the thread is to respond to several people in one post, by using the Insert quote button, rather than making concurrent posts.

I'll post a schematic later, when I've got time.
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