Auto Bed Level Inductive Sensor for 3D Printers

[@stewedapple]

Tried your diode method on my project with 5xNPN sensors, works flawlessly! Previously I was tearing my hair out with this problem. Thanks mate, your video was a big help!

[@raymonschepers994]

Thank you very much for this bright and clear tutorial my friend. Thanks to your help i can continue making my 3d printer much better working in essence. And i needed this mental upgrade so much in my learning proces to produce better quality prints just right now. One can only wish receiving help of this level, this grade once stumbled upon the subject matter between those three proximity sensors. Just without choosing to go gamble. This is huge (it really is for me!!)

[@timejinx]

dude, thank you. I got in to 3d printing to learn more about adrino and electronics explanations like this are very helpful. I ordered your pnp 5v from bang go because of you!!!

[@Tech2C]

Great, glad you found this interesting.

[@timejinx]

got my pnp sensor for banggood does not work at 5 v :( but does work at 12 mehh guess i will be getting some resister:(

[@Dombi3D]

Why don't we use capacitive sensors? With them the glass sheet would be not a problem. Now I want to upgrade my 3d printer with a proximity sensor and I don't know why don't buy LJC18A3 regard LJ18A3 type sensors.

[@thiagorodriguesdeoliveira5746]

My "12v" npn nc probe is finally working! I had to adapt my array of resistors cause i'm using 13v. Now the signal pin has 5v as well. Thanks a lot!

[@MakerFarmNL]

Very good video. Thank you for showing two options to connect the 12 V NPN sensor (also with the diode). For me the first option (the voltage divider) did not work, even though everything worked as it was supposed to, but my MKS BASE 1.5 board just did not see the 5V output as a high signal (tried with and without pullup resistor settings etc in Marlin). The second option however (with the diode) is way more elegant for the 12V sensor and very clean to install. Thanks for your explanation and time to make this video.. I have learned something... again! :-)

[@Xiltch]

I wired the NPN directly to my boards Z min port and it is functioning. It is a rated 4mm sensor and i get a detection distance of 1.74mm which is just over 40% of the rated distance on an aluminium board. My tester gave me a reading of 4.7vdc on the supply pin.

[@limbopferd]

Could I ask for a description on how you wired it? I've got a capacitive sensor working with 5v, but I don't know how to wire it to my two pin Z port.

[@FronbondiSkegs]

Great video - even years on ...

[@TheDiverJim]

Another great video! I really love the topics of your videos. And the hypercube is really well designed.

[@whitcwa]

The saturation voltage of a silicon transistor is not the same as a diode forward voltage drop. It is typically around 0.2V, not 0.6V.

[@razzix2]

Love this video! For the PNP voltage divider setup how do we tell which pin to send the voltage of the two? Is it just as easy as throwing on a multi meter to see which is negative and connect the neg pin to the voltage divider?

[@razzix2]

Just in case anyone else has the same questions. I tried it on the neg pin of the zstop on my ender 3 board and it did not work - moved it to the positive pin and it works as expected. Hope it helps!

[@SawyerShack]

Thank you so much for that video. Your instruction was very easy to understand and you have answered a lot of my questions. I do have an NPN switch and it is Normally Open. I have decided to use the diode in reverse option to wire up my switch. Are there different types of diodes or what specs should my diode have? Also, what is the likely-hood of that diode failing and killing my board? Should I also include a fuse of some sort?

[@KennethScharf]

Please note that while some PNP probes might work on 5v, the sensing distance might be reduced when operating at less than 12 volts. I thought that those NPN sensors would have 'open collector' (or open drain) outputs,' and would operate a load connected between a positive source (5-12 volts) and the grounded output signal based on the wiring diagram. You could then connect a pull up resistor to 5V to generate a positive true signal to the RAMPs board. Certainly they show a load connected to the output between +12 and ground! If the output with no trigger is due to an internal pull up to 12 volts, (measure the resistance between the output and +12 with no power) then it should be safe to connect a 4.7 or 5.1 volt zener diode between the output and ground to clamp the voltage at a safe logic level and set the Ramps input to inverting wtih pull ups. Your method of using a series diode would work, but I might suggest a Schottky diode, which has a lower voltage drop for better S/N at the input. PNP sensors supply a 12v output signal to a load connected between the output and ground. For these you need a level converter. Connect the output signal to a 470-1000 ohm resistor in series with a 4.7 or 5.1 volt 1 W zener diode to ground. The cathode of the zener is connected to the resistor, the anode to ground. Take the output across the zener diode. The endstop input should be set to non-inverting, and pullups are disabled. In both of these cases I am assuming a "NO" type logic, IE: the output is active when triggered for positive logic. You can buy stainless steel or iron foil and apply this to the glass plate on the print bed to increase the sense distance since the sensor works better with iron based materials.

[@Tech2C]

Very informative, thank you.

[@GoatZilla]

Good info. I would have liked to see if the distance really is better at 12v. These short sense distances make using them in printers difficult.

[@Tech2C]

GoatZilla I haven't noticed a distance change between using the NPN probe at 12v, and PNP probe at 5v.

[@GoatZilla]

Tech2C That's too bad then. Thx for letting us know.

[@iuries]

The diode trick is just awesome! it's simple and effective. thanks!

[@karandex]

FYI, i did connect a square type inductive sensor to ramps directly without divider and it worked... for a while then i had to use different pin for probing.

[@ADCbits]

Hi folks (: I don't know if this was addressed yet, but just found out (making a printer for my friend) if you are using Marlin or other firmware with an easy option to implement inductive probing and are using glass bed, you can use 4mm distance inductive probe. Trick is that your glass should be no more then 3mm thick and you have to apply copper tape approx 20x20mm under the probing points. I tried it yesterday and it works! Hope this helps someone. ... and since copper tape is 7um i think you could easily stack two together on top to get perhaps longer distance detection, but like i said it works with single layer of tape under 3mm glass.

[@gemici6701]

Hello, first of all thank you for this nice education. I am using 24V power supply in my 3D printer and want to connect Capacitive PNP NC Sensor LJC18A3-8-Z / BY. How many resistance I need to use for this. Thank you very much in advance.

[@Zodliness]

If you secure a thin steel pad over each sensor to the bed, it greatly increases the sensing distance on aluminium based printing beds.

[@joshuahafel4506]

Great video, but one question. If I have an aluminum heat bed, with a glass printing surface, will this still work, or will the glass mess up the leveling?

[@unclezeds]

Ok I’ve pulled my ACKLP and upgraded it with a 5V NPN NO inductive sensor to the Z Min and have the sensor working. HOWEVER when it does a Auto Calibration, the inner circle of data spots senses fine, then the sensor which is -39mm in y 0mm in x goes off the bed and crashes the whole thing. What am I doing wrong?

[@ErlendDavidson]

With capacitative probes the logic is normally to keep them as close to the bed as possible (1mm above nozzle). I've heard this isn't necessary with inductive probes as their resolution doesn't depend on sensing distance. Is this true?

[@der-andyman]

Hi, so I am going to use an inductive sensor as abl sensor on my Ender 3. Is it now better to power the sensor directly with the 24 volts of the power supply and reduce the signal down to 5 volts or should I just power the sensor with 5 volts (if it works with 5V)?

[@der-andyman]

@@FronbondiSkegs Ok, I used a relay which operates with 24v and passed the 5 V when closed directly through. :-)

[@FronbondiSkegs]

I deleted my previous reply as I didn't include the entire solution I used. To recap - on the Ender3Pro, being 24V, I use a resistor divider 20k/5k on the sensor output to get approx 4.7V output. I then use this 4.7V to drive the gate of an N channel mosfet (2N7000) which has its drain and collector pins connected between the Z-endstop pins (the source pin goes to ground side of the Z-endstop connector). This mod also requires updates to the firmware to change the polarity of Z_MIN_ENDSTOP_INVERTING.

[@der-andyman]

@@FronbondiSkegs thanks, I guess I understand what you did there :-)

[@madorax251]

what sensor type your use? npn or pnp for ender 3?

[@der-andyman]

@@madorax251hey, I am using NPN sensor with a relay

[@flupsiflo]

Great video, but I tried the one from your link and it is not working with 5v :(

[@lemanxr]

Hi, i have open sensor and when it detects metal diod is red but m119 taling open, not trigged. Please help. I have NPN No

[@_Piers_]

Thanks very much for the explanation of how a diode works in place of a divider. I'd seen it suggested somewhere, but couldn't figure out what they were doing :)

[@FthEke]

I did all of instrucitons. I am using voltage divider 100k and 150k ohm resistor, I am connecting with ramps Z_min port but when i send M119 Gcode, Z_min looks always open but İnductive sensor's led is lighting.

[@Exlr8Films]

I prefer the sensor that is NC as its constantly sending a signal. Because if the probe for some reason stopped functioning the satiety features of the software would detect no signal and therefore not attempt a probe. However if its NO the firmware wait for a signal, but this also means the probe could be completely unplugged.

[@B0G0MIP]

again a great video, thanks. My HyperCube is about 70% finished, getting into the electronics part now. so this video came just in time :)

[@Tech2C]

Great!

[@backwoodsking]

Thank you so much for making this video! I've been trying to sift through low quality, not clear forum and youtube tutorials for days looking for the answer to wiring this probe. This video is fucking perfect! Thanks!!

[@rondynellypinheiro1834]

Do you recommend or not, use the resistors?

[@joecox9958]

Common types are LJ12A3-4-Z/XY，here postfix XY can be AX/AY/BX/BY means NPN NC/PNP NC/NPN NO/PNP NO, in Merlin cfg the Z_MIN_ENDSTOP_INVERTING needs to be set as false/true/true/false, respectively. Using 12V power we need 15K(serial)/10K(to ground) divider to get down to ~5V, using 5V you might need to add 10K pull up for NPN or pull down for PNP then it should work. 8/12/18 sensors stem size D15x50/D21x60/D29x68, washer dia is larger. .cfg pull up is too weak no need to use. Sensor is an oscillator, when close to metal it stops oscillating changes output.

[@Substancia3D]

Hi there, i have a LJ18A3-8-Z / BX 8mm and cannot detect the alluminum bed behind the glass build plate, not even the glass, but detects metal, any ideia?

[@alimohammadmojarad5945]

There is another way, using a 12v relay means that the sensor can work on 12v without being actually connected to the board by any means right?✌😜

[@vegard77]

Is there probes with longer detection distance out there ? 1.6mm is to little if you use a glassplate of 2mm....

[@rossk7927]

TLDR: It's safe to plug a 12v source into a 5v pin on a micro **as long as there is at least 7k ohms in the line** (no resistor divider needed). Frankly one could use any resistor above 7k likely up to 500k or more without degrading performance - Personally I would likely use a 47K or 100K resistor as I have loads of those on hand. Click "read more" to understand why! Why this works: Inside the micro there are diodes on every (I/O) pin which clamp the pin voltage to within one diode drop of the ground and supply rails. These diodes aren't particularly beefy when under sustained load, they are largely intended to protect against moderate ESD or other short transients. Therefore it is perfectly safe to send far more than 5v into a pin as long as the current flowing into the pin and through the clamping diode is sufficiently limited. The datasheet on the 2650 doesn't state what these diodes can handle but 1mA sustained is likely very reasonable and conservative. Where 7k comes from: Input voltage of 12v Micro supply voltage of 5v (ignoring diode drop makes for a more conservative calculation) This leaves 7 volts (12v - 5v) which will need to be dropped across the resistor + clamp diode circuit. Using Ohms law (V = I * R) rearranged to solve for R (R = V/I) we can calculate the resistor value needed to limit the current to 1mA Gives: 7v / 1mA = 7k ohms. And there's no need to really push 1mA through this diode - the digital IO on a micro is very high impedance and really doesn't require much current flowing into it - *choosing a resistor which is much higher than 7k ohms is advised!* _At some point if you choose an extremely high resistor value (likely in the 10's to 1000's of Megaohms) the micro will begin having trouble sensing the signal so don't go too crazy as you will likely get cross talk issues far before this point._

[@osyrass]

I am just setting this up now and trying to get the resistors in place using the NPN. When I measure voltage with no metal I am getting 6.6 v, when I am close to metal I am getting .66v. As I understand it 6.6 will fry the Arduino as it is above the 5v threshold. Could it be the 10% tolerance of the resistors I sourced?

[@cheif10thumbs]

Why not just epoxy a steel washer to each sensor point thereby increasing detection distance? It's outside the build area. Just a thought.

[@skyrim4713]

how much watts is they 2 risistor added up to

[@bobymck]

thanks for the video!! great thing!! Have you tried not using the voltage divider and connect the S directly to the S pin on the board? (ONLY the S from the sensor, so only one cable) and the sensor takes the the 12 v directly from the PSU? it would trigger the same, since it would send the negative to the S ping that is 5V + causing the same action as it would a mechanical endstop. mine is working this way without any issue.. Just thought your probably could test out for others, it would probably make life easier.... cheers

[@speesy]

You have the resistors backwards.. 10k to ground and 15k to sense wire.

[@P0llut1on]

what do you think about BL-Touch? do you have plan to insert it in your printer?

[@joop1987]

Is it possible to use mesh bed leveling like the Prusa I3 with this setup?

[@mikerman50]

Chris yes, I have this on my Anet A8

[@girrrrrrr2]

Yes you would configure that in Marlin But to auto size the bed and stuff, you gotta have the special bed that prusia has.

[@joop1987]

I guess it needs an aluminum bed for the sensor to work correctly? Glass bed would not work, correct?

[@girrrrrrr2]

Chris Yes there has to be a surface of a conductive material, aluminum, steel or copper.

[@bigfilsing]

+CHris You could use a capacitive sensor on a glass bed. I have them on 2 printers and they work fine. Down side is they are 18mm diameter and definately need the resistor voltage divider . Have never tried the reverse diode.

[@davektowner]

I was wandering if anyone could help me... I had a 12v inductive sensor working through an opto-coupler until a had a soldering iron incident that damaged the wire close to the body of the sensor... So I decided to go for a a 5v sensor to replace it (cleaner install). When I hook up the sensor and run an m119 it always says triggered (or open if I reverse the logic) and doesn't change state when a metal is out near the sensor. The red led reacts to the presence of metal but the end stop state doesn't change. I have used a multimeter to check voltages...when open the sensor passes 4.90v through the z-min signal wire, when triggered this voltage drops to 2.2v. I tried enable the pull down on the z_min in marlin and reflashed. In doing this the triggered voltage now drops to 1.6v. It's my understanding that in order change the state of the end stop marlin needs.the triggered voltage to drop below 1v. Given that I'm using a 5v sensor j thought this would be plug and play.. Can anyone offer any advice? Thanks in advance

[@samraza5802]

hi bro can you please tell me that can we connect PNP NO sensor directly in anet a8 printer or we also need to do changes in farmwear please tell me in detail because i made my own 3d printer but i stuck in installing sensor please help me to resolve i will be very thankful to you ?

[@x9x9x9x9x9]

I am getting 5.4V on the signal wire of my sensor. Will this fry my Anet A8 board? I assume not but its high enough to make me uncomfortable about trying it without asking someone if they think its fine. I am using the 10k/15k resistor setup.

[@Vido89]

My PNP prob which works on 5v does not work its always open

[@Sonicshadow191]

Hi @Tech2C, Ive recently been getting a problem with the probe set up on my cube. I'm using the 5v pnp as you've used here from your link to banggood and ive also connected it up with your quick switching mpx connectors. What I've noticed recently is im not getting a reliable level on consecutive G29s and occasionally my readouts add 1 or 2mm to random probe points. Some people have suggested buying a different model of sensor or adding diodes somehow to the line but before i do and in the time it'll take for the parts to arrive i'd like to know if there's something i can do to fix it as clearly it works on your build without problems. I did notice a new line of text on the screen in your MPX quick connecter video mentioning a diode. Is this something im missing in my build or was that for use with a different probe set up? I really dont want to have to mess with the current MPX wiring if possible If it helps I am having issues currently on my big printer running on the ramps board, marlin 1.1.8 (i think) but I plan to move this head over to my new "stock" hypercube build that will run on the Big Tree 1.3 when Banggood send me the parts im waiting on.

[@GeekinaCave]

The capacitive sensors have the same behavior between PNP and NPN?

[@vanlaser5385]

How about this model (on aliexpress): LJ18A3-8-Z/BX-5V ? It's advertised to be working at 5V, and has 8mm detection.

[@Mariz650]

Hi, thank you for yur video. Other than the probe, what needs to be done do put this to work?

[@omnom2455]

As always best of the best Full instruction and fun to watch and cute accent

[@Khasawy]

im not sure what im doing wrong but i cant get the printer to use the prob for homing the Z axis when i home bot X and Y go to 0 and the printer tries to find a Z but sense they XY are both on zero they are not on top of the bed.. Please help

[@shaunwhiteley3544]

Sorry, stupid question but I've printed out, your Bowden conversion ( great) but when I come to swop the head, my carriage is different, the four holes I have seem standard for the Prussa i3 but I think yours is none standard??? How does your x carridge attach please? I cannot seem to find a pic at the back to work it out. Thanks

[@neuxstone]

Great info and presentation. Could you please tell me where I would be hooking in to my Cr10 board. Does it just use the z end switch terminal using ground and output signal? I'm new at this sorry but others may have the question.

[@Aki-sp8dq]

I have a problem. I connected the inductive npn no probe, the red light turns on but it keeps slamming to the bed. I tried resistor with 12v (it should work. On 5v) anet 8.

[@trevor99z]

Have you considered trying BLTouch? I've used an inductive sensor before switching to BLTouch and haven't looked back since. One pro to BLTouch is you don't need a metal bed, and I understand bed weight may not be a big concern on a CoreXY compared to any prusa designs, but less weight is always better :)

[@Tech2C]

I've heard of BLTouch but haven't used one as of yet. Someone made a BLTouch mount on Thingiverse for the Hypercube. I'll take a look at one in the future.

[@skyrim4713]

Tech2C. how much. Watts resistor should i.get

[@Fabricefabrap]

great video does heat from bed not affect good working of these sensor ? (probing before heating or not ?)

[@Tech2C]

I find it best to pre-heat the bed before homing as the bed will expand with a temp difference.

[@tidbits5220]

Great Video!! thanks. I tried both the Voltage divider and the diode...and in the end the divider didn't work for me, but the diode worked perfectly...and the DIode was easier.

[@guillaumegiraudon3044]

Is it possible that your voltage divider resistor values on the video are revered ? If I do the math with 10k between Output and Vout and 15k on ground to Vout, I get 7.2V whereas if I reverse the resistors, I get 4.8V ?

[@danielbull6709]

Hi - yes I had the same thoughts. It appears the labeling of resistors is reversed at 8:16 in the video. The 10k ohm should be on ground (blue wire) and 15k ohm should be on the sensor output (black wire) to get 4.8v output.

[@Hojaloha]

this video is always so helpful

[@wildraccoon5237]

Thank you, now I understand that I bought the wrong type of probe

[@sci3dprinthome723]

Excellent video with perfect explanation! Thank you very much.

[@PhilWaud]

Great video, thanks once again. I'm thinking very seriously about building a hypercube, I know you have suggested some updates, but can I just ask you - if you were going to start from fresh, would you vary from your designs? Happy new year!

[@Tech2C]

I'm happy with the results. I could suggest to print the parts solid (100% infill) to ensure they are as rigid as possible.

[@charlesworton4020]

NOW you tell me?!!? AAAAAAHHHH!

[@Rubafix989]

He told this already in prevous videos. 15% was for quick iteration

[@alicante1989]

i have proximity sensor DC 10-30 V and can i use this with break out board cnc work with 5v

[@bigfilsing]

Great video. Should be compulsory viewing for anybody starting out with ABL

[@MegaMonkeyboy85]

thank you for this ! I've seen bigger orange inductive sensors, do you know what it means ?

[@TheAndriyan]

I used it to speed sensor for spedometer. Is It possible in high speed over 50mph the sensor is not able read almunium? My oem speed sensor use 100mA but my proximity sensor 40mA is It effect the reading? Can I Put npn transistor to incrase the Amp? Please help..

[@bensbuilds4732]

for your bowden drive, do you have a link to files that are for the actual drive gear? thanks!

[@mikegallo6429]

hi, when you say min z endstop plug the yellow wire , you refer to the S+ pin right of z_min . 2nd question if i read 3.1 volts from the yellow wire and when triggered the npn 12vd feed i get 0 , is it normal or a use the wrong resistor ??? thank you for the info . can i use a 1n4001 diode for the signal.

[@mikegallo6429]

thx for the help tutorial, got it, i use a separate power supply to turn on sensor, wrong idea. i connected the sensor to the same power supply the feed the arduino and use the 1n4001 diode .Now work and some mod to the firmware too.I changed the z-probe-pin to z-min-pin don't if does anything but i changed and works.

[@willkim9134]

what is the distance between the bed and sensor

[@IceTurf]

Should I shield the cable?

[@consaka1]

What about glass over aluminum like the cr-10 has?

[@BassemMichel97]

the reversed diode methode worked fine for about 20 min or so. after a while it failed for some reason and it passed the 12v to the arduino. which caused all the electronics to frie except the ramps shield. including the lcd and the arduino. juat use the voltage divider. its safer!

[@Tech2C]

That's very unlucky. RepRapers have been using the diode method for years. Checkout the reprap forums for discussions on the matter. Sorry to hear yours failed!

[@geilecharlie]

can you make an picture to show me how you connect this npn sensor with resistors on the printer? i cant get it rto work :(

[@3dprinting591]

I got the PNP sensor for my hypercube but wont work it gets 4.96 volts the light shines a little bit but on 12v it works just great.. I now going to use it white the resistors.

[@girrrrrrr2]

I was trying to setup marlin for my printer, and its throwing me errors saying i need to enable either x min or x max. Ive tried disabling max, min, both, neither, and its still throwing me that error Any ideas?

[@SubsitudeMyOwn]

Does anyone know what is happening with my setup? I've used an NPN induction sensor with the same voltage divider. When untriggered the voltage is about 3.36V, when triggered the voltage is 0.35 ish. When using the m119 the state of the sensor is cycling between open and triggered. Almost every time i send the m119 command, it has changed state. What the heck is wrong, and how to fix it? Any help would be much appreciated!

[@bullxtfpv8567]

I rarely comment something... but this is awesome... tnx a lot

[@lIPunto40lI]

@Tech2C which board you putting this on?

[@tomaszburczyk7478]

Hey. Could you make a video how to connect LJC18A3-H-Z / BX to the SKR 1.3 disc step by step? I think fub people would be very grateful ...

[@marit1060]

I just use a lm7805 in the output of the sensor and send the output of the lm7805 to the mother

[@neuxstone]

Great vid and explanation. Noob question. How do you get into the firmware to make changes?

[@VaibhavSarda]

Download Arduino IDE from Arduino website, Refer to the build log playlist for more details, he has mentioned all the necessary links and shared the files.

[@pablocano9285]

My inductive sensor has only two wires Can you help me?

[@dddxp7311]

hy, im having some trouble with temperature, if i got my bed more warm, the measure changes, what could it be?

[@andyherbert2304]

Aluminum expands a decent amount when heated that might be what you're measuring

[@charlesworton4020]

Ordered the sensor thru your link - mks sbase card also needs 3.3 - 5V on XYZ switches. Resurrected Zonestar Prusa I3 clone is cranking out hypercube parts as I type. Parts flying into my mailbox thick and fast. Chaos reigns. Will keep you posted re Mks sbase controller card and 3.2" touchscreen. >Charlie

[@Tech2C]

haha thx.

[@azinefoulak6761]

je n'arrive pas a configurer mon capteur PNP sur prusia I3

[@azinefoulak6761]

on pourras mete un regulateur 5V entre le Z-port et le capteur pour éviter le risque de tension de 12V emporter sur le pc

[@FreeformRock]

Very useful information, this helped me a lot. Thank you!

[@paulrautenbach]

Nice explanation and demonstrations. Thanks.

[@TheRaven1942]

man i build a printer for my school and this is the last part of it and we cant understand the wiring set up we are geting so mad

[@ypsonar]

sir, can this sensor detect glass surface ?

[@ikomu8907]

nope you need capacitive sensor

[@stanleypendleton2731]

aaaahhhh my head is going to EXPLODE!!!.......great video

[@jasoneyes01]

Why not buy a 5 volt inductive probe NPN... Can be had for 5 bucks on Aliexpress. Also triggers at 8mm.

[@chloemcholoe3280]

I heard they don't work well

[@luisff7030]

Please test your diode idea for reducing the voltage, because it doesn't work. It will be always 5 volts What you can do is to use a 5v zener diode, in reverse, and a resistor(10k for example) in series. Or use 7 normal diodes, in forward, and a resistor (10k for example) in series.

[@anthonymarconi3174]

I had good results using a 5 volt regulator across the signal to groud

[@Tech2C]

That's good.

[@chloemcholoe3280]

Wouldn't that add delay?

[@ianmcmill]

Thank you for this video. One question: For convenience because I am lazy: Which sensor should I get? A PNP-NO 5V, which I can directly connect with a dupont plug onto the Z-Min endstop or NPN-NO 12V with voltage divider where +/- is connected to 12v of the controller board and the sense-pin connected to the Z-Min signal input?

[@rok1475]

Zero volt does NOT mean ground !!! Zero volt on voltmeter means that the circuit is either shorted to ground or not connected to anything (=open circuit)

[@descent8275]

is there a way to sense glass?

[@rhyse302]

DESCENT Sadly no, you'd need a capacitive sensor. It's a really similar concept though

[@descent8275]

align g ugh where to buy, how to implement in merlin?

[@jfvenier]

Perfect explanations, thanks !

[@showlowwings]

Has anyone try to mess with a 7805 voltage regulator, so no matter what voltage input.....the output would be always 5 Volts?... Or is it even possible?

[@chloemcholoe3280]

I assume it's add uneven delay making it horribly inaccurate.