bart_b
UV LED modulator, Overview
Overview of the UV led modulator.
It consists of an opamp controlled constant current source. The opamp used is the TLC272 (one of my favorite opamps) driving an FZT953 PNP transistor. The current delivered to the UV led is about 18mA.
The LED has a BAT42 diode and a resistor and capacitor snubber over it. The goal is to replace the LED by a 405nm laser diode, these diodes are very sensitive to over and undershoots and need to be carefully protected.
Parallel to the LED is a BS170 mosfet that rapidly turns off and on to modulate the LED.
The schematic is more or less based on this circuit from a Laserjet II laser driver:
www.repairfaq.org/sam/rg1-1594.jpg
On this page:
UV LED modulator, Overview
Overview of the UV led modulator.
It consists of an opamp controlled constant current source. The opamp used is the TLC272 (one of my favorite opamps) driving an FZT953 PNP transistor. The current delivered to the UV led is about 18mA.
The LED has a BAT42 diode and a resistor and capacitor snubber over it. The goal is to replace the LED by a 405nm laser diode, these diodes are very sensitive to over and undershoots and need to be carefully protected.
Parallel to the LED is a BS170 mosfet that rapidly turns off and on to modulate the LED.
The schematic is more or less based on this circuit from a Laserjet II laser driver:
www.repairfaq.org/sam/rg1-1594.jpg
On this page: