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Question about inverting endstops.

Posted by jammersplace 
Question about inverting endstops.
April 04, 2016 10:11AM
I purchased the fastbot3d BBP and to tell you the truth is has been great. The only issue I currently have is that I use the optical endstop for bed leveling. The endstop is inverted. With the Fastbot BBP there currently is no way to invert the endstops. I know there has been requests for it in their forums. I would like to ask the reprap community is there a way using a transistor to invert an endstop? After I get this inverted I can fully test the autobed leveling and start printing fully again. I have printed with the new board and it works great just I miss the autobed leveling it has spoiled me.

In short I need the endstop to put 5v out when triggered and 0v when not triggered.

I would like to say sorry if this is in the wrong forum. I also did a search and all the ones I seen was to change in the firmware.

Edited 1 time(s). Last edit at 04/04/2016 10:12AM by jammersplace.
Re: Question about inverting endstops.
April 04, 2016 04:07PM
Search for using a mosfet with endstops, I think you can do it that way but I'm not very familiar with It. The other way is using a relay module, so get a relay module where the coil is switched at the voltage of your endstop signal eg 5v/12v whatever. I am assuming your endstop puts out 0v triggered and 5 or 12v open, so connect the endstop signal to the input on the relay, power the relay from your printer board. Then wire 5v to the com on the other side of the relay and send the NC output to your printer endstop signal pin.

When the endstop is open the relay will be closed so the NC output gives 0v. When the endstop is triggered the relay opens and the NC output gives 5v.

These modules have leds to show status and give a mechanical click when switching. There is a tiny delay in switching so don't set your homing feed rate too high.

Here is a 5v module [pages.ebay.com] but 9v and 12v modules exist also.
Re: Question about inverting endstops.
April 04, 2016 04:48PM

any transistor with a hfe > 100 will do.
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