Hi

I have a little prodject going on with my 3D printer CR-X from creality.
I want to put an auto bed leveling on it, but my circuit bord only supports 12V and the power supply is 24V

I tryed using the Voltage devider with 2 simmular resistances but my Capacitive Proximity Sensor uses about 200mA so the voltage drop is to much.
So my question is is there some way to modify the board that I'm using? Change the resistors? I could always use a 12V power suply from the outlet or an power drowngrader, but I want it to be a complet kitt whitouth the extra parts.


The board
https://www.ebay.com/itm/12V-1-Chan...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

https://www.thingiverse.com/thing:2906283/comments

The Sensor
https://www.ebay.com/itm/DC6-36V-3-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

The printer
https://www.creality3d.cn/creality3d-cr-x-p00252p1.html

The components on the board

R1= Brown, Black, Red, Gold = 1Kohm+-5%
R2=Brown, Black, Orange, Gold =10Kohm +-5%
Led: Probably a normal 5V led or something?
Optocoupler
http://www.everlight.com/file/ProductFile/EL817.pdf
Also se picture

Please correct me if I'm wrogn when you look at the pictures of the resistances and let me know if you need more information

 

The easy way is to in series with a 60Ω/10W resistor from +24V to +12V device.

 

Hello,

Why does it say that the sensor can be powered with 6 - 36 Volts?
Just power the sensor with the 24 Volts from the printer.
Replace the 1K resistor R1 with a 2K2 resistor on the board.
The output of the sensor goes to the input of the board and the other side of the input of the board can go to the 24 Volts.
The output side can stay as drawn.

Bertus

 

Hi Bertus

Thank you for answering.
The sensor supports voltage ut to 36 volts, but It's the card I'm Woried about. So if I got al the info right it should work like the athatchment in this post? I'm kinda new to resistance and how everything works.

 

Hello,

I said 2K2 wich is 2.2 KOhms.
22K will likely not give enough current for the opto coupler.

Bertus

 

Hello,

I said 2K2 wich is 2.2 KOhms.
22K will likely not give enough current for the opto coupler.

Bertus

Sorry. I'll try it out and see how it works, I should have a som lying around here. Thanks all your help.

 

The sensor appears to have an open collector output. You don't need an optocoupler at all. You can directly drive an input that operates at any logic voltage by using a pullup resistor (e.g. about 5k for 5 volt circuits should be OK, connect between the 5 V supply for the board and the input), connecting the "common" wire from the sensor to the "common" (ground) for the logic circuit and the negative of the supply for the sensor, and the positive for the sensor to whatever supply is being used.

I strongly recommend you test this first with a meter before making the connection to the logic circuit (microcontroller), just in case the description for the sensor is incorrect. If you measure the voltage between the sensor output and the sensor negative with the sensor's supply connected and nothing else, you should see no change (maybe a few millivolts) in the voltage at the output of the sensor if it really is open collector.

There MAY be some reason that is not apparent why you would want to use the optocoupler, such as some unusual connection between the power supply that would be used for the sensor and the logic circuit.

 

Sorry. I'll try it out and see how it works, I should have a som lying around here. Thanks all your help.

Hello ! have the same problem. How doees it work ? is 24V power supply working with 12V optocoupler with the 2.2kohm resistor ? Diagram from bertus is correctly set up ? Thanks !