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Keith,
I understand your point. I am very new to laser diodes and this is my first experience with designing 8 laser diodes that switch at 100us (that s the need for the project)...
Do you have any designs with the closed loop optical power control circuit which suits my needs ? Can you please...
Keith,
Thanks for all the help.
I read all the replies from everyone about my issue.
I even mailed thorlabs about this and they suggested me to buy a laser diode driver.
I talked to my prof under whom am doing this bio-mems project and he still asks me just to control the current for the laser...
I used a higher value resistor between vcc and collector and limited the current to 70mA but the problem was that the voltage drop across the resistor is so high that am not able to get a decent voltage drop to the load am connecting after the resistor which in this case is my laser diode which...
Hi all,
I am using a 2N2219A bipolar NPN transistor for my project.
I want the transistor to work in saturation region so that the drop across Vce=Vce(sat)=.3V.
but i need Ic not to increase more than 70mA.
i tried 2things :
1. made Ib=7mA, so that the transistor is in saturation which worked...
Oh I didn't know that we could not set up both current and voltage. The part no of the laser diode is HL6738MG.
So what else can I do ? Because the data sheet of the laser diode asks for both the operating voltage and threshold current to operate it.
I have to design for 8-different laser...
Hi keith,
Ya the opamp i am uisng is a high current precision amplifier(OPA551).. it can drive upto 200mA. So i don't think there s problem with opamp.
I tested one of the laser diodes and it just needs its correct operating voltage and operating current.
The purpose of the DAC is to give 8...
Hi all,
My project is to build a circuit to drive 8-different laser diodes. I am using a micro controller to switch between 8 different channels of diff laser diodes. I desiged a driver circuit with a transistor as switching device.
My aim is : to provide 2.5V and 45mA to the laser diode...
I am using MPlab to write my C code and PICKIT2 to load the program in the PIC16f887.
---------- Post added at 17:58 ---------- Previous post was at 17:56 ----------
I am using a DC power supply.
I have connected the +ve terminal to the Vdd pin.
I have connected the -ve terminal to gnd and...
I am trying to switch my Port D outputs by a time of 1 sec. below is the code that I am using. Only Rd0, Rd1, Rd2 glow. after Rd2 it switches to Rd0 and it keeps looping. I ve set the register for port D properly but still my other 5 LEDS are not glowing.
Also only when I short RB3(pin 36) to...
Tahmid,
I got what your point but regarding the connection. I get a +5v with respect to only the -5v point and not the ground in the power supply. I tried connecting vss to just ground but later I measured the input voltage going in Vdd and it was 0v. I also tried connecting the negative...
The problem is that I ve tried what you are telling me but still I have a strange problem.
I connected 8LEDs in port B as well as 8LEDs in Port D. I get the LEDs glowing in port D when i program it with this set up but when i remove 2LEDs from RB1 and RB2, the LEDs in Port D stop glowing. I...
I have written a simple PIC code to make all the LEDs glow in the port D.
Please tell me if I am missing anything.
My code is
#include<htc.h>
#include<pic16f887.h>
//#include<delay.h>
//#include<time.h>
#include<stdio.h>
#include<conio.h>
#ifndef _XTAL_FREQ
// Unless already defined assume...
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