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Need help on Infrared LEC......

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umliu37

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hi guys, i need some help with my robot project ......so here is the issue i facing now :

. I need to drive a Infrared LED, .. and the LED works when it under the defaul testing conditions list on data sheet.

But i need to drive the LED by the Microcontroller pins, but the pin has a very smaller output voltage and current than the default LED testing condition.

If i use an Op-AMp to amplify the pin output , that might works , but another drawback is the 741 Op--AMp need a +15 and -15 power supply ,maybe the battery will increase the weight of my robot ........ so is there any other approach i can amplify the signals????

BTW, anyone can tell me if not the Square wave can be amplified by Op-amp???

thanks for any helps ..
 
A transistor according to the common emitter configuration for switching purposes.
Square waves don't need to be amplified with op-amps if they come from the PIC. You can use a transistor also for this purpose.
 
A transistor according to the common emitter configuration for switching purposes.
Square waves don't need to be amplified with op-amps if they come from the PIC. You can use a transistor also for this purpose.

thanks for your advices ,,, i will try

BTW, did the transistor power supply Vcc, has to be 15 v ??? I think it could be 5V regular .
 
switching on a IR LED? yeah.. 5V regulated is good enough for moderate ranges.. My friend's reached half a meter. You can add the range using lens if you want.
 
i just thought that if i use NPN transistor , it has Vbe = 0.7 v ,as the turn-on voltage. Howerver, my output voltage from MCU is only 0.2V.....

so i still need an amplified input voltage for turing on the transistor first..........
 
That doesn't seem right. I could buy a voltage threshold of .2V for a logic one on an input but not .2V output voltage. A transistor will work fine.
 
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