photodiode with op amp

Thread Starter

Dany096

Joined Dec 18, 2020
4
hi, i bought a op amp max407 amplifier and i want to connect with photodiode but it didnt work. anyone know why or a good circuit to operate
 

KeithWalker

Joined Jul 10, 2017
1,786
There are two types of photo diode. Those that emit IR and those that detect IR. Do you have the right type?
Do you have it connected the right way round?
 

Thread Starter

Dany096

Joined Dec 18, 2020
4
in Vin i give 5V.the resistor of feddback is 1M and the other resistor is 100k. the output voltage is 0.5V.when light up the photodiode the voltage of vout decreases instead of increase.. and in that point i stop because it seems strange to me
 

KeithWalker

Joined Jul 10, 2017
1,786
The circuits you are using have a both a +V and -V supply with reference to ground. They will not work if you are using a single 5V supply.
It is very misleading for a beginner when an op-amp circuit is drawn without showing the how the power supplies are connected.
 

Thread Starter

Dany096

Joined Dec 18, 2020
4
this is true and difficult to me so i searched and found an op amp that needs power supply 5V in pin8 and ground in pin 4 , so that I do not have to make a circuit with V- supply
 

KeithWalker

Joined Jul 10, 2017
1,786
Here is a single supply circuit for an IR detector. It should work with the op-amp you have but you will need to re-assign the pin numbers on the diagram: :
IR detector.jpg
 
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