PinkDuck

joined 1 year ago
sorted by: new top controversial old
What's a simplest way to get -5v from +/-12v? in c/[email protected]
[โ€“] [email protected] 1 points 1 year ago
  1. it does nothing ๐Ÿ˜… I just forgot to remove it from the sim
  2. you mean like power it with 0+5v? I think it won't work with negative input voltages then, right? and I'm using tl074 and I'm not sure that 0+5v is enough juice for it, and I use remaining 3 opamps for other stuff, so it's not really an option for me. the sim didn't have shottky diodes, so this measurements are not 100% accurate, but I used this approach to protect arduino inputs in another project, and it worked well. And yeah, I cranked up the input signal to +/-10v just to check the clipping, it'll normally stay within +/-5v

I already ordered PCB for the prototype. I hope it'll work fine. Thanks a lot for your help :)

Electronics for toddlers? in c/[email protected]
[โ€“] [email protected] 2 points 1 year ago

maybe something like littlebits kit? I haven't tried them myself, but they look fun, educational and kids friendly (not sure about 3yo thou)
https://www.youtube.com/watch?v=E7B0mWvnE1Q

What's a simplest way to get -5v from +/-12v? in c/[email protected]
[โ€“] [email protected] 1 points 1 year ago (2 children)

No, with 0 Ohm I get a perfect 0+5v sine, just as I need. It's the other way round, it'll amplify the signal and clip off the top at about + supply voltage when you increase the resistance in the feedback loop, but it's not exactly square wave, as the bottom part of sine will remain intact. I use clipping schottky diodes to protect the arduino from voltage outside 0+5v range, this way if you increase input signal to say 20v peak to peak, you'll get more square-ish wave in 0+5v (I've attached the schematics)

What's a simplest way to get -5v from +/-12v? in c/[email protected]
[โ€“] [email protected] 1 points 1 year ago (4 children)

ah, a little bit of thinking helped me realize that I don't need 1k in inverting loop and then I'll get 5v instead of 5.05v :) and 100k can also be replaced by 1k

What's a simplest way to get -5v from +/-12v? in c/[email protected]
[โ€“] [email protected] 1 points 1 year ago (5 children)

it worked! (at least in the sim)
thanks a lot!
I'm not sure I got all the math right, since I get 0 - 5.05V on the output, but it's not a deal breaker for me.
I attached the schematics, but not sure that images in comments federate from kbin to lemmy, so if you don't see it, try opening an original link to this comment.

What's a simplest way to get -5v from +/-12v? in c/[email protected]
[โ€“] [email protected] 1 points 1 year ago (7 children)

thanks! gonna give it a try tomorrow. I'm pretty new to this, and never used opAmps in non-inverting configuration, so I missed this option

What's a simplest way to get -5v from +/-12v? in c/[email protected]
[โ€“] [email protected] 2 points 1 year ago

Oops, the schematics didn't attach for some reason, let's try to add it here

14
What's a simplest way to get -5v from +/-12v? (kbin.social)
 

Hi! I'm working on an arduino project that has a -12v/0v/+12 psu. +12 is fed directly into arduinos voltage regulator, so there's also a +5v line available. I need to convert a -5v+5v signal to 0v+5v to feed it into arduinos analogue input and I've already mocked up a schematic in circuitjs based on an opamp that seems to do what I want. The only problem is that it needs -5v to shift the signal to be unipolar. I know that I can invert +5v using another opamp, but maybe there's some simpler way? I'd really like to avoid adding another opamp just for this? In this schematic I used simple voltage divider to get the needed voltage, but I guess that's not the best approach?

TLDR: I have -12v, 0v, +12v and +5v, what's the easiest way to get -5v?