Electronic adjustment and indication for filament sensor
I was having trouble with mechanically adjusting filament sensor so came up with the idea to add electronic trim to set ir sensor detection point, also led indicator to see the sensor status which helped a lot and first time had a successful multi-material print after purchasing the upgrade kit.
So following modifications are performed.
1. Removed the transistor R3 and R4 from the filament sensor and shorted gate and drain pads of the transistor to convert it into an analog sensor, now sensor outputs in range 0v to 5V.
2. Connected old opamp comparator circuit which had an output led and inverting input connected to a trim which supplies 0v to 5v depending upon position to the output of filament sensor and output of opamp to mainboard, now can use trim to adjust trip point for ir sensor instead of mechanically adjusting it.
If somebody thinks this would be useful I can post detailed modification instructions.