New filament sensor on Github
https://github.com/prusa3d/PRUSA_Laser_filament_sensor
rev 02e
any ideas on what has changed? (have not looked into it yet)
Edit: so there is a fuse? and a resistor added? I guess it is to prevent the melting issue? But not necessarily improve detection reliability? What do you think?
https://github.com/prusa3d/PRUSA_Laser_filament_sensor/blob/master/rev.02/laser-sensor.pdf
https://github.com/prusa3d/PRUSA_Laser_filament_sensor/blob/master/rev.02e/laser-sensor.pdf
Re: New filament sensor on Github
There's a resistor (current limiting) and what looks to be a varistor/thermistor added (probably also for current limitation). Don't think it has anything to do with filament detection, more likely to prevent overheating/burning out the sensor.
Re: New filament sensor on Github
I see two differences in the schematic
1) Addition of 200 k pullup from Vref/EN to +5V. This resistor is shown in the TI data sheet app note for the LSF0102 level translator.
The data sheet says explicitly
The 200 kΩ, pull-up resistor is required to allow Vref_B to regulate the EN input. A filter capacitor on
Vref_B is recommended.
It's not likely that the lack of this resistor causes burn out, but it (and the missing filter cap on vref) might explain some of the mal-performance.
2)There's now a 50 mA fuse on the 5V input. This should prevent burning in case of mechanical damage/short on the board.
They should add the filter cap as recommended on the datasheet.