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How to determine the resistance for IR circuit diagram?

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doubledragon

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Infra red

How to determine the resistance for IR circuit diagram? any formula?
 

Re: Infra red

Your Photodiode is in wronge direction, you must reverse the diode direction.
 

Re: Infra red

leotim said:
Your Photodiode is in wronge direction, you must reverse the diode direction.
Click to expand...


Ok.
Do u know how to determine the resistance value?
 

Re: Infra red

You want to use this circuit as a switch (Light Detector) or as an intensity meter?

Switch
In this mode, the transistor is in saturated state when there is no light and in the off state (Ic = 0) when the light is present.

Intensity meter
In this mode, the transistor never saturates and output voltage (Collector voltage) is always greater than 0 and less than VCC.

Which mode matches your needs?
 

Re: Infra red

leotim said:
You want to use this circuit as a switch (Light Detector) or as an intensity meter?

Switch
In this mode, the transistor is in saturated state when there is no light and in the off state (Ic = 0) when the light is present.

Intensity meter
In this mode, the transistor never saturates and output voltage (Collector voltage) is always greater than 0 and less than VCC.

Which mode matches your needs?
Click to expand...


Switch
 

Re: Infra red

If:

VCC = 12V
I_dark = 1 nA
I_Light = 100uA
β = 200;
V_BE(ON) = 0.6V
V_CE(SAT) = 0.2

R1 = 120 kΩ
R2 = 5.6 kΩ
R3 = 1 MΩ
 

Re: Infra red

leotim said:
If:

VCC = 12V
I_dark = 1 nA
I_Light = 100uA
β = 200;
V_BE(ON) = 0.6V
V_CE(SAT) = 0.2

R1 = 120 kΩ
R2 = 5.6 kΩ
R3 = 1 MΩ
Click to expand...

If Intensity meter ? with 5 Vcc
 

Re: Infra red

what about intensity meter mode?
 

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