IR led driver doubt (which model is better A or B?)

[nikhilele]

IR led driver problem

I have to options to drive leds
I think Figure A is better one and it can give more power,
But i would like to hear from u.
Which one is better driver figure A or Figure B

 

[ehsanelahimirza]

Re: IR led driver problem

hi


fig a is recommende not only bcz of power use but also in this type of serial circuits if one led is out of order than u cant use other also
and the circuit becomes useless

 

[VVV]

Re: IR led driver problem

Figure A is better.
With about 2V across each LED and some voltage drop across the transistor, there is hardly any voltage left out of the 5V supply, so you may not get the maximum current you think you do, therefore, the intensity may be lower for figure B.

 

[nikhilele]

IR led driver problem

i totally agreee with your answers ehsanelahimirza
and VVV,
But i have seen in many ciruits the ir leds in series especially when they are directly driven by 555,
This says that they are ignoring the power of parallel connection, or they are doing it for saving one resistor and simplicity.

But i will stick to FIG A Only
thanks for your replies

 

[VVV]

Re: IR led driver problem

Obviously, the current and power loss for the parallel connection are twice as high, for the same light output.
So if you have a high enough supply you can use it. Combinations series/ parallel are also possible.

 

[ehsanelahimirza]

Re: IR led driver problem

seen in many ciruits the ir leds in series especially when they are directly driven by 555,

hi

yes u r right. but actually some where more intensity of light is needed and some where same signal is needed at two different loacations of circuit.so it will just depend upon ur requirements that what u want to drive