Basic Non Inverting Amplifier Schematic wanted to explore different op-amps, help is much appreciated.
Hi & Welcome..
On what particular circuit/effect you want to "explore" different op-amps..??
A simple buffer is all I'm after, I'm trying to create a neutral buffer at first, and then perhaps 10dB of gain if I can figure that out.
You might like this.
http://philsal.co.uk/wp-content/uploads/2018/12/Analogue-Guitar-Pedal-Design.pdf
I believe it contains a simple recipe for what you're after (page 7), along with a lot of other useful building blocks for guitar pedals.
Check the datasheet for the sepecific opamp you're using too, that will tell you most things you need to know about its implementation.
You could try these too:
https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg (https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg)
(https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg)
In the schematic it's marked as half of a TL072, but that doesn't make much sense for a single op-amp. Use whatever suits.
For the buffer-with-gain, you can experiment turning R11 into a 100K pot for variable gain.
HTH
Thankyou guys for your input.
The Pedal Design PDF looks simple yet informative.
And the Electric Druid looks super simple.
Welcome, Animal. If you are using a single opamp, like a TL071, don't forget to double-check the pinout, because they are different! Disregard if you already knwo this :)
Quote from: ElectricDruid on March 05, 2021, 11:37:11 AM
You could try these too:
https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg (https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg)
(https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg)
In the schematic it's marked as half of a TL072, but that doesn't make much sense for a single op-amp. Use whatever suits.
For the buffer-with-gain, you can experiment turning R11 into a 100K pot for variable gain.
HTH
I can't find this on his site, can you help?
How would you design the circuit to go from 0 to unity, then have an additional 10db amplification available by separate pot?
Answers on a post card :)
replace the 22k r11 with a 50k potentiometer. you can leave out the 1k if you want.
(https://i.postimg.cc/njcZHDGm/series-pot.png) (https://postimg.cc/njcZHDGm)
cheers
Quote from: Animalbeats on March 05, 2021, 06:37:04 PM
How would you design the circuit to go from 0 to unity,
We wouldn't 'cause unity is the minimum gain for non-inverting configuration..
Do searchs here for
"buffer"
"IC buffer"
"opamp buffer"
there have been many posts and thread over the years.
Or read some books
maybe some opamp inputs should have diode clamps
"Neutral" is is something that does not make sense.
Even with a distortion less stage the input resistance interacts with the pick-ups volume, tone control, cable etc.
Neutral to what?
10k will sound different to 1 meg etc
Then what RC HPF will the stage have?
Too low a frequency can "mud up" by boosting lows
and more things
https://www.diystompboxes.com/smfforum/index.php?topic=93699.0 (https://www.diystompboxes.com/smfforum/index.php?topic=93699.0)
From http://www.muzique.com/lab/buffers.htm:
(http://www.muzique.com/images/buff7.gif)
(http://www.muzique.com/images/buff8.gif)
Quote from: antonis on March 06, 2021, 07:27:45 AM
We wouldn't 'cause unity is the minimum gain for non-inverting configuration..
Well, they said "separate pot", and that's as simple as putting a Volume pot after the gain stage. It works the opposite of the way they said - unity to +10db, then turn that down - but this is better for S/N reasons, which is why it's pretty much standard procedure. You can put the knobs physically on the pedal whichever way makes most sense to you.
Quote from: Animalbeats on March 05, 2021, 06:26:45 PM
I can't find this on his site, can you help?
The full-size schematic is on the site at the link I posted:
https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg (https://electricdruid.net/wp-content/uploads/2021/03/StompboxBuffers-scaled.jpg)
It doesn't feature anywhere else because I only chucked it up there when you asked about it!
These circuits are absolutely standard, absolutely basic "building block" stuff. I put a buffer like this on the front of pretty much every pedal I design, and I'm not the only one! Here all I did was put an output cap on it so it can be used alone.
Buffers like these make the pedal largely indifferent to what feeds it, so it can give a reliable result in *any* situation, unlike some older pedals that are really fussy and people spend ages on forums discussing whether they sound better after this or that - that's a sign of a dodgy design! If it's well-designed, it should sound good whatever you plugged into it, and whatever you plug it into. That's pretty fundamental!
Quote from: antonis on March 06, 2021, 07:27:45 AM
Quote from: Animalbeats on March 05, 2021, 06:37:04 PM
How would you design the circuit to go from 0 to unity,
We wouldn't 'cause unity is the minimum gain for non-inverting configuration..
yes, 0db is unity!
Quote from: iainpunk on March 06, 2021, 03:50:21 PM
yes, 0db is unity!
I don't think OP has got the slightest idea about decibels..
I even think he hasn't got the slightest idea about his own queries, but let it be..