Hi,

I am trying to make a circuit that will convert a voltage output signal from ESP 32 that ranges from 0 - 3.3V and turn this into 0 - 10V.

Some points are

* There is a 10V supply available at the ESP 32 that can be utilised.
* The ESP 32 will run off a 3.7 V 2000Mha lithium-ion battery so want it to use low power.
* I have LM358 op-amp here but if I need other/better components ways to do it open to ideas

Just to note I have only been doing electronics for a very short time so my understanding is limited but I am very keen to learn how I can accomplish this!

Thanks

Travis

 

hi trav,
Welcome to AAC.
The LM358 with a 10V supply will limit at approx 10V -1.5V =8.5Vout

E


Check this link for Rail to Rail for =>10Vsupply
https://www.mouser.co.uk/c/semiconductors/amplifier-ics/operational-amplifiers-op-amps/?output type=Rail to Rail

 

hi trav,
This circuit will work for you using a LM358 and a 12V supply.
Added a simulation with a10V supply, note the limiting at approx +8.5v
E

 

Thanks for the reply Eric.

I can work with 8.5V for now.

Tomorrow I will send you a drawing of how I have wired it to see where I am going wrong as at the moment cannot get it to work!

 

hi trav,
This circuit will work for you using a LM358 and a 12V supply.
Added a simulation with a10V supply, note the limiting at approx +8.5v
E
View attachment 265792
Awesome thanks I will try this circuit tomorrow and let you know how I go. Appreciate it!

 

Awesome thanks I will try this circuit tomorrow and let you know how I go. Appreciate it!

 

Which program are you using to make the schematic?

 

hi,
LTspice, it is a free download.
E
https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html

 

Awesome thanks mate

 

Hey, Eric please guide me with what I am doing wrong here. Output is showing 8.5V even if I remove the 3.3V on IN1- input to make 0V. Could you maybe please draw how I need to connect it.

 

Man, I am feeling dumb right now so much to learn!

 

Gd'Day trav.
Try this. I assume it is a LM358 Op Amp.?

Connect the Non Inverting input to 0V, pin #3.
Remove the -10V from the Vss, pin# 4 and connect to 0V.

You should measure on Vout pin #1 , close to 0V.
Post what you measure

E
Do you have a photo of the project to post, on case you have not wired as shown.?

 

Yep using LM358

 

Ok I will do that now getting 057mV

 

hi,
Thats OK.
Now put 1v on the non inverting input pin#3, you should measure 3v on Vout pin #1

E

Update:
NEVER leave pin #3 disconnected.!

 

ok I will try that now

 

Sorry I had to make a volatge divider as only had a 3.7v batttey


IN+v0.886Mv
OUT1 1.12V

 

Added a pot to the battery 1V is 1.24V on the output

 

hi,
OK,
The amplifier is set for a Gain of times 3 for the Non Inverting Input.
Check that the resistors are 5K and 10K as shown in my diagram.

Don't forget if you put 3.3V input on pin #3, the Vout will show about +8.5V, when using a10V supply for the LM358.

Get a potentiometer say 10K variable and connect that across +3.3V supply, then connect the potentiometer wiper to pin #3.
You can then vary the input from 0V through +3.3v and check the Vout/

E

 

I am using a 4.7K instead of the 5K could that be my problem?