help with dummy load and setting ddl current

[sciullo779]

i made a basic ddl circuit i found on this forum, and made a diode series that was measured at 4.5v drop. my problem is it was a mishmosh of like 9 diodes and the 1 ohm resistor to make that measured drop, is that my problem, even though it measured out at 4.5v drop?

could my problem be that i left the 1 ohm resistor in series with the laser diode?

oh also when i measured everything with the dummy load it read 6.97v @ 80mA which seems too high, could it be the battery (i used a 9 volt)?

but anyway i discharged the cap, soldered the diode in, popped the batt back in and the violet diode was bright as hell.....for 3 seconds... then it got really dim and died, the axiz module was really hot too and that was the end of my first blue violet diode

 

[lasersbee]

First.... you need only 6 Rectifier Diodes for a Blu-Ray Test load...

With 9 diodes you will not get the correct load to adjust the
Driver properly...
That is why at the current you stated you had such a high voltage
on the output of the Driver...
The current/voltage was adjusted to high... Which blew your LD...


Jerry

 

[sciullo779]

even though when measured with my dmm the voltage drop was 4.5 volts combined?

 

[ElektroFreak]

ALL silicon diodes drop .7V per diode. .7x9 = 6.3v drop. .7x6 = 4.2v. Don't just trust your meter, do the math.