How to determine the resistance value?

[doubledragon]

Determine R

How to determine the resistance value?

 

[fobyellow]

Re: Determine R

what is it?
IR receiver?

 

[doubledragon]

Re: Determine R

what is it?
IR receiver?

Yes, IR receiver

 

[dfullmer]

Re: Determine R

Is it receiving analog information or digital?

 

[pqtam]

Re: Determine R

How to determine the resistance value?

Determination of R depends on the working condition of the transistor and the IR receiver:
R2: depends on Icmax, collector curent gain of the transistor. If the signal is digital, the transistor work in switching mode, you can take R2=5V/Icmax, for most low power transistors, it should be in K or tens Kohms.
R1 and R3: depends on bias current of transistor and the phototransistor used, collector curent gain of the transistor. You can select R1 in practice by having phototransistor fully closed (dark), the R1 should provide enough bias to fully open transistor.R3 limits the base-emiter current, for most low power transistors, it should be in tens Kohms.