Bought lj12a3-4-z/bx from Folgertech, wiring isn't working...

Followed Tom's guide on youtube to wire this up, and it's not working. Here's what happens.

If I have NO resistors inline, hook it up to a 12v rail on ramps board, the sensor works as it should. Meaning, I can put the sensor tip near metal, and the light triggers. The output line is sending out 12v. Not good. I haven't hooked that up to the ramps board yet.

Now, if I wire up the sensor with resistors inline, like Tom's guide, I still get 12v coming out on the output line, and the sensor WILL NOT trigger when near metal. The light just stays off.
I've wired it with a 20k resistor on the black "output" line, and a 10k resistor bridging from the blue "ground" wire to the black wire further down the black line ( after the 20k resistor ).

Can anyone help???

**edited to add a picture of how I wired it**

Edited 2 time(s). Last edit at 03/20/2016 09:55AM by Gannicus.

Now I'm reading that this is an NPN sensor, and no resistors are required??

In Tom's guide he used this sensor specifically, and used resistors.

Here's another odd thing. I removed all the resistors. Wired the wires straight through...Tested the sensor using one of the unused 12v rails on the ramps board where the hotend and heatbed connect. I get 12v coming out the output line, but the sensor will not trigger when held near metal. If I connect the sensor DIRECTLY to the 12v power rail on the power supply, I get 12v coming out the output line ( black ) and the sensor light trips when held near metal, and the voltage drops to 0.06v.

If it's an npn NO sensor then your wiring looks okay. If you're having problems try this first. Just wire it direct to the endstop +5v,0v and signal. Try it. Some of these work on 5v saving you a lot of trouble. If supplied with 5v then the signal is 5v also.

If this doesn't work a voltage regulator might work, you need an lm7805 with the signal fed into the input and the output going to ramps.

I'm writing a guide to all this now and the issue with these sensors is that the transistor i.e. Npn or pnp seems to work the other way around to the way it works in general in electronics. So npn sensors provide positive voltage signal and pnp ground the signal pin.

Also the output to the heatbed and hot end are not 12v rails they are pwm outputs so they pulse on and off and only when heatbed or hot end are set to be on.

Edited 2 time(s). Last edit at 03/20/2016 02:00PM by DjDemonD.

For this sensor type you want endstop logic set to true and internal pull up off. Let me know how you get on I'm trying to remove all the confusion that happens around these sensors. Up till now it's been a lot of guesswork.

I just said eff it after I posted, and wired it to 5v on the z endstop. Worked perfect. Thanks.