Hello! So I'm facing kind of a problem right here. Im susposed to build this circuit



Now the resistors im using are 1k and 2.2k Ohm, and the input voltage we need to set to 3V,over a GUI that we are executing over python.Now I've connected everything to my PC and whenI measure the outpot voltage I get around 2,9V.This doesnt seem right to me. I've done the calculation per hand like this (3V * 2.2)/ (R1+R2). And I get around 2,06V. Now I'm 99% sure I've done everything right,and still my measerument is way off.Here is how it looks



Can anyone tell me what I'm doing wrong? Thank you in advance!

 

Bad contacts..

You should be getting around 1V, put the Resistors into the supply feeds directly and twist the ends together with the ADC feed wire to make sure of a better connection.

Do yo have a DVM ?

 

Hello,

Are you trying to measure the DAC output via a voltage divider with the ADC?
In your drawing the 2K2 is at the top and the 1K at the bottom.

Bertus

 

Hello,

Are you trying to measure the DAC output via a voltage divider with the ADC?
In your drawing the 2K2 is at the top and the 1K at the bottom.
View attachment 224206
Bertus

Yes exactly, we are trying to measure the DAC output via a voltage divider. I've tried swapping the resistors already, and I still get the same result

 

Using the picture from bertus, you should have about 2V across the top resistor and about 1V across the bottom resistor. Maybe you wanted to switch the two resistors.

 

Hello,

When you get the same result with swapping the resistors, there must be a bad contact.
Also check the program to measure the voltage.
Try to make the circuit on a different part of the breadboard.

Bertus

 

Hello,

When you get the same result with swapping the resistors, there must be a bad contact.
Also check the program to measure the voltage.
Try to make the circuit on a different part of the breadboard.

Bertus

Okay will do, but what exactly is a bad contact?

 

Hello,

Breadboards make the contacts with strips that should grab the wires.
When such strip is malformed by pushing in a to thick wire, it might not make the contact anymore as it is bend.
This can be the cause of bad contacts.

https://learn.sparkfun.com/tutorials/how-to-use-a-breadboard/all
https://www.seeedstudio.com/blog/20...board-wiring-circuit-and-arduino-interfacing/

Bertus

 

Yea I've tried it on a diffrent part of the breadboard,still the same.

 

Hello,

As @Dodgydave asked, do you have a Digital Volt Meter?
If so, check the voltage accross the resistors.

Bertus

 

Hello,

As @Dodgydave asked, do you have a Digital Volt Meter?
If so, check the voltage accross the resistors.

Bertus

Unfortunately I dont

 

Hello,

You can buy a multimeter for 64 Euro with a lot of features:
https://www.desertcart.at/products/...requency-tests-diodes-transistors-temperature

Bertus

 

Hello,

You can buy a multimeter for 64 Euro with a lot of features:
https://www.desertcart.at/products/...requency-tests-diodes-transistors-temperature

Bertus

Yea, I dont think that will work haha. I've gotten this for my birthday from my parents,and I'd doubt they would give me 64 Euros for a multimeter.I'll figure it out eventually. Thank you!

 

I'd doubt they would give me 64 Euros for a multimeter

There are much lower cost meters that do less. I remember having 0 money. That also happens when you are much older.

 

Hello,

The DT830 is a cheap multimeter:
https://www.amazon.com/Tekpower-DT8...909011&refresh=1&rnid=1248907011&s=hi&sr=1-32
You can have it for about $ 15 at your doorstep.

Bertus

 

Hello,

The DT830 is a cheap multimeter:
https://www.amazon.com/Tekpower-DT830BT-21-Range-Digital-Multimeter/dp/B0160GT8DW/ref=sr_1_32?dchild=1&keywords=cheap+multimeter&qid=1607195335&refinements=p_n_condition-type:6358196011,p_72:1248909011&refresh=1&rnid=1248907011&s=hi&sr=1-32
You can have it for about $ 15 at your doorstep.

Bertus

No need I've figured it out,one of the resistors wasnt working properly,I've swapped it out and it works fine.