Inductive probe on 24v SKR 1.4 July 04, 2020 01:52PM |
Admin Registered: 11 years ago Posts: 3,096 |
Re: Inductive probe on 24v SKR 1.4 July 07, 2020 07:44PM |
Registered: 6 years ago Posts: 265 |
Re: Inductive probe on 24v SKR 1.4 July 07, 2020 07:48PM |
Registered: 6 years ago Posts: 265 |
Re: Inductive probe on 24v SKR 1.4 July 11, 2020 04:19PM |
Admin Registered: 11 years ago Posts: 3,096 |
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MMcLure
Replacing the 1N1848 that is listed in the blog post that has a 0.7V or so voltage drop with a 1N5818 Schottky with a ~0.35V drop may make it work. I'm sort of surprised that the sensor is only dropping the voltage to 0.7V - it should be much closer to 0.
Don't try to use the more common 1N5817 Schottky - it's reverse voltage rating of 24V is too close for comfort.
Re: Inductive probe on 24v SKR 1.4 July 11, 2020 05:20PM |
Admin Registered: 11 years ago Posts: 3,096 |
Re: Inductive probe on 24v SKR 1.4 July 11, 2020 05:58PM |
Admin Registered: 16 years ago Posts: 13,888 |
Re: Inductive probe on 24v SKR 1.4 July 12, 2020 02:47AM |
Admin Registered: 11 years ago Posts: 3,096 |
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VDX
... hmmm ... if the VO level ist +24V, then be sure, there is an internal resistor from the OUT1 pin to GND! - if it's an "floating" input circuitry, then with "OFF" transistor it will be pulled to 24V throug the 10k resistor!
If "floating", then add a 2k7 resistor from OUT1 to GND to define a safe signal level ...
Re: Inductive probe on 24v SKR 1.4 July 12, 2020 02:53AM |
Registered: 6 years ago Posts: 1,007 |
Quote
VDX
... hmmm ... if the VO level ist +24V, then be sure, there is an internal resistor from the OUT1 pin to GND! - if it's an "floating" input circuitry, then with "OFF" transistor it will be pulled to 24V throug the 10k resistor!
If "floating", then add a 2k7 resistor from OUT1 to GND to define a safe signal level ...
Re: Inductive probe on 24v SKR 1.4 July 12, 2020 05:25AM |
Admin Registered: 11 years ago Posts: 3,096 |
Quote
MKSA
Quote
VDX
... hmmm ... if the VO level ist +24V, then be sure, there is an internal resistor from the OUT1 pin to GND! - if it's an "floating" input circuitry, then with "OFF" transistor it will be pulled to 24V throug the 10k resistor!
If "floating", then add a 2k7 resistor from OUT1 to GND to define a safe signal level ...
Indeed, it is very simple. I was looking at the SKR 1.4 schematic as I intend eventually to buy one.
Most probably the output of this probe is an open collector NPN and in that case it needs close to nothing, just implement the same protection circuitry found on the X, Y endstop as the probe doen't have anything, just direct to the CPU. In case Z endstop is used (It is what I do) just put protection diode as it is missing (strange ?). Or use the ExDET input and configure firmware.
Yet the best is not tho use this archaic method and have the detection done by the nozzle touching the bed (piezo, strain gauge whatever...).
Re: Inductive probe on 24v SKR 1.4 July 12, 2020 12:11PM |
Registered: 6 years ago Posts: 1,007 |
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Ohmarinus
Honestly in the build I'm doing the inductive probe is perfect for it's application. However, I did order a precision piezo kit last week and hope to receive it soon so I can at least install that on the Delta. And I bought an imitation piezo kit from Aliexpress to compare the kits and their quality etc. I might make a through-hole piezo disc and design a hotend mount for the current project. But first I want to use the inductive probe because it's what I know and I like it so far on my other printer
The probe I'm going to use for this project is a PNP NO probe. Are there any drawbacks by using a PNP NO probe??
Re: Inductive probe on 24v SKR 1.4 July 13, 2020 11:55AM |
Admin Registered: 11 years ago Posts: 3,096 |
Quote
MKSA
Quote
Ohmarinus
Honestly in the build I'm doing the inductive probe is perfect for it's application. However, I did order a precision piezo kit last week and hope to receive it soon so I can at least install that on the Delta. And I bought an imitation piezo kit from Aliexpress to compare the kits and their quality etc. I might make a through-hole piezo disc and design a hotend mount for the current project. But first I want to use the inductive probe because it's what I know and I like it so far on my other printer
The probe I'm going to use for this project is a PNP NO probe. Are there any drawbacks by using a PNP NO probe??
Too bad it is a PNP !
A NPN pulls the output to 0V which is easier to interface with low voltage electronic.A PNP pulls it to the probe power supply, here 24 V !!! So you need to clamp it to 3.3V. Just a 6.8K resistor in serie and connected to a protected input like E0DET or E1DET to produce about 3V as input V. Then define this as probe pin. To use the probe pin requires to protect it as E0DET.