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Electronics / Problem getting the full power of Excitation LED
« on: February 15, 2017, 01:36:03 PM »
Hi all,
I am able to get the Ca-images of neurons with the miniscope.
But I am having a difficulty in getting the right LED power.
I measured the current flowing the LED for the excitation LED.
At low intensity level (about up to 40%), the current increased linearly.
But after a certain intensity, the LED intensity or the current didn’t increased any longer.
Three other miniscopes showed the similar results.
I also tested with other PCs but they didn't worked properly, either.
I thought there was voltage drop somewhere in the circuit of the CMOS.
3.3V and 1.8V had no problem.
But I have found voltage drops in 5V as the LED intensity increased.
And there was no more increase in the LED current with no more voltage drop.
Here are the conditions and results that I got.
-Length of Cooner coaxial cable = 80 cm
-DAQ board V2.01
-CMOS PCB V3.0
I'd appreciated it if anyone has any ideas on what to check. Thanks!
I am able to get the Ca-images of neurons with the miniscope.
But I am having a difficulty in getting the right LED power.
I measured the current flowing the LED for the excitation LED.
At low intensity level (about up to 40%), the current increased linearly.
But after a certain intensity, the LED intensity or the current didn’t increased any longer.
Three other miniscopes showed the similar results.
I also tested with other PCs but they didn't worked properly, either.
I thought there was voltage drop somewhere in the circuit of the CMOS.
3.3V and 1.8V had no problem.
But I have found voltage drops in 5V as the LED intensity increased.
And there was no more increase in the LED current with no more voltage drop.
Here are the conditions and results that I got.
-Length of Cooner coaxial cable = 80 cm
-DAQ board V2.01
-CMOS PCB V3.0
I'd appreciated it if anyone has any ideas on what to check. Thanks!