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bigtreetech / BIGTREETECH-SKR-V1.3

32bit board with LPC1768, support marlin2.0 and smoothieware, support lcd2004/12864, On-board TMC2130 SPI interface and TMC2208 UART interface no additional wiring is required
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[GUIDE] SKR 1.4 TURBO with LJ18A3-8-Z/BX inductive probe #390

Open gec100 opened 4 years ago

gec100 commented 4 years ago

Had this sensor for long time working great on my custom made prusa clone and now I'm building a new corexy printer around SKR 1.4 Turbo board on 24V.

I'm not a electronics engineer but I can find my way around.

The sensor needs 6-36V to work properly, but probe connectors on the board can accept only 3-5V. On 12V boards this sensor needed to be connected to the 12V pin (spare Fan connector) with voltage divider described here http://reprap.com/wiki/Z_probe

In this 24V setup, resistors had to be changed. With https://www.allaboutcircuits.com/tools/voltage-divider-calculator/ I calculated that my resistors need to be roughly 4:1 (R1:R2) in size to get the output voltage below 5V needed for the Z-stop probe pins. That would be cca 4kΩ for R1 and 1kΩ for R2 or 8kΩ for R1 and 2kΩ for R2 . You get the point. I had at my hands 5k1 for R1 and 1k for R2 giving me cca 3.9V that is well inside 3-5V range.

here is my very rough schematics:

SENZOR

As I said I'm not an electronics engineer but this works for me. If you have any comment I would be grateful.

lautarobusto commented 3 years ago

thank you very much. saw a buch of vids on how to use this probe but all used ardui+ramps and similiar probes using 5v, but no one mentioned something about using a voltage divider to get the signal to the correct voltage.

gec100 commented 3 years ago

glad to help when I can