Laser Diode CW Driver

Thread Starter

Félix Del Prado Hurtado

Joined Sep 25, 2019
2
Hello Everybody!
I am interested in feeding a laser diode (LD) with 2.5V and 210 mA. I am using basically a Darlington configuration as shown in the schematics.
In order to prevent any damage to the LD I am using a RL.
I have used 3 Op-Amps of the same kind labeled as Op-Amp #A, #B and #C all of them new ones
The list of elements that I am using are:
  • (FG) Frequency Generator: HMF2550, f= 10Hz,V_offset =2.000 V & 0.005 Amplitude (Output impedance = 50 Ohm)
  • (LD) Laser Diode: LNC728PS01WW
  • (Tx) Transistor: PN2222A NPN
  • (Pot) Potentiometer: Potentiometer 5W and 25 Ohms
  • (Z) Zener Diode: 3V
  • (OA) Op-Amp: AD848JNZ (PIN1 & PIN8 are not grounded, ot connected between them, simply not connected.
  • (PS) Power Supply: from a PC
  • (RL) Load Resistance = 2.2 KOhm
zjthT.png
The values of the Voltages obtained are listed in the next picture.

5Kg3o.png

Can someone Help me, why there is not voltage drop through the RL? Why the PINs 1 & 8 show these values?

Thank you very much in advance.
 

Bordodynov

Joined May 20, 2015
2,377
Will your T2 transistor be able to dissipate approximately 1.5 watts of power ((12-2.5-2)*0.21 = 1.575)? This question arises when connecting the laser.
 
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