Hello, I am having difficulty converting this analog signal trying to take advantage of several LM358s that I have from other projects.
I have an esp32 which I can set signals between 0-3.3v but need to scale them to 0-5v. I have looked at references that it is possible, but I am not successful in implementing the circuit according to what I interpret.
Any help or suggestion is greatly appreciated. Maybe LM358 is not ideal, but if possible it would help me a lot.
Thank you so much!
Yes, that is possible, but with op amps that are not "rail to rail", like the LM358, you will need a positive power supply of at least 7V, so that the LM358 output can reach 5V.
What will be the load on the 0-5V analog signal?
@jremington
Maybe I could use a 9v or 12v source?
Thanks for your reply.
Yes.
Hi,
Do you want to convert 0 - 3V3 LOGIC to 0 - 5V LOGIC?
OR
Do you want to convert a changing signal 0 - 3V3 to an AMPLIFIED signal 0 - 5V?
What is the device that needs 0-5V?
Tom.. 
Yes, I need to convert a changing 0 - 3.3v signal to an AMPLIFIED 0 - 5v signal.
I need to control the power of a module that is responsible for heating a submersible heater and I can regulate its power between 0-5v.
For this I want to use an LM358 amplifying the analog signal of an esp32 with 3.3v.
Since the answer is positive to the fact that an LM358 operational amplifier can be used, my question is more or less how the circuit would look for this amplification.
Thank you!
Basic noninverting amplifier with a gain of 5/3.3.
There are countless tutorials on the internet! A couple of examples follow.
Don't forget to add power supply decoupling capacitors, which are always required but not always shown on a schematic diagram.
https://www.arrow.com/en/research-and-events/articles/fundamentals-of-op-amp-circuits
Save yourself some work, you need a different operation amplifier, the LM358 does not go from rail to rail.
No op-amp can do this. Op-amps are designed to output analog signals, not control power. They cannot provide the current that a heater would need.
The way to control a heater is not to use a variable voltage. You should use a PWM signal to switch the current to the heater. For example, instead of giving the heater 2.5V, you would give the full 5V, but use a PWM signal to control a MOSFET with the PWM signal set to 50%. The heater then receives a voltage & current which is either full power or zero power at any instant in time, but averages 5V x 50% = 2.5V.
Hi,
Can you please post a link to spec/data of the submersible heater controller?
Thanks.. Tom..
@PaulRB Sorry my bad English of translator.
"I need to control the power of a module that is responsible for heating a submersible heater and I can regulate its power between 0-5v".
I meant that if I provide a 0-5v analog signal I have a module that interprets the analog signal and regulates the temperature of the submersible heater, what I intend to do is the same as establishing a set point in a PID. But my only question is how to amplify 0-3.3v signal to 0-5v using LM358.
In any case, your answer also helps me. thanks dude
Please post a link to the module product page or data sheet.
The more information you provide, the fewer misunderstandings, and the less time wasted by you and other forum members.
Your solution was 100% effective without any drawbacks.
The module I am talking about is not commercial, it is homemade by who knows who, I am reconditioning a system that someone brought me.
This was worked out. Thank you!
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