[kolias]

Got this gadget to show the Spindle cooling water temperature in my cnc but I don’t understand the 12VDC power wiring connections.

Do I connect the 12vdc to terminals 3/4 and the switch in terminals 1/2 is wired internally or I connect the 12vdc as shown in the attached PDF?

And polarity? Does it matter which terminal I connect the pos / negative?

Thanks

[Al_The_Man]

It appears to allow 12v DC or AC input, most likely has steering diodes internally.
In that case, if using DC you can connect it either way to 3 & 4,
Term. 1 & 2 are the N/O contacts of the relay. so you can use these to switch what ever circuit you need to, as long as it does not exceed the current rating of the relay.
It is a thermostat, so it switches on off at the set temperature. using the NTC terminals

[kolias]

Many thanks Al

[CitizenOfDreams]

As Al said, 12V can be connected either way to terminals 3 and 4.

The relay contacts (terminals 1 and 2) I personally would wire to the safety/E-Stop circuit so the machine would turn off if the coolant overheats. If you have a normally closed E-stop mushroom (and you should!), you can wire the relay contacts in series with it.

[kolias]

Very good idea CitizenOfDreams, thank you

I was thinking about it and I do have a mushroom type E-Stop but for now terminals 1 and 2 are not connected because I only run the spindle not more than 14K RPM and not for long cuts. Spindle has always been cool to the touch. I will complete the wiring soon (to the E-Stop).

When I first connected the unit (just happened NEG was at terminal 3 & POS at 4) it didn’t work (the screen was black) and I thought I did something wrong but I didn’t find anything wrong. Then I switched the power supply so the POS was at terminal 3 and NEG at 4. Then the screen became alive. Means terminals 3/4 are polarized as per my experience.

[Al_The_Man]

).

When I first connected the unit (just happened NEG was at terminal 3 & POS at 4) it didn’t work (the screen was black) and I thought I did something wrong but I didn’t find anything wrong. Then I switched the power supply so the POS was at terminal 3 and NEG at 4. Then the screen became alive. Means terminals 3/4 are polarized as per my experience.

That reflects on the instructions being very poor then, IMO.

[kolias]

The instructions are the worst I have seen BUT the package was shipped from UK!

[CitizenOfDreams]

When I first connected the unit (just happened NEG was at terminal 3 & POS at 4) it didn’t work (the screen was black) and I thought I did something wrong but I didn’t find anything wrong. Then I switched the power supply so the POS was at terminal 3 and NEG at 4. Then the screen became alive. Means terminals 3/4 are polarized as per my experience.

That means the thermostat has a half-wave rectifier, as opposed to a full-wave bridge. Wrong polarity will not damage it, it just won't turn on (as you have observed). Now take a red marker and draw a "+" sign above terminal 3 for future reference. :wave:

[Al_The_Man]

The instructions are the worst I have seen BUT the package was shipped from UK!

Things must have gone south there since I left !

[mactec54]

Got this gadget to show the Spindle cooling water temperature in my cnc but I don’t understand the 12VDC power wiring connections.

Do I connect the 12vdc to terminals 3/4 and the switch in terminals 1/2 is wired internally or I connect the 12vdc as shown in the attached PDF?

And polarity? Does it matter which terminal I connect the pos / negative?

Thanks

As Per the wiring diagram 1/3=+ Load and Negative is 4- it clearly shows which is the load connection

[Al_The_Man]

As Per the wiring diagram 1/3=+ Load and Negative is 4- it clearly shows which is the load connection

That is only when you use the supply for the load also,, the main issue is/was that the instructions do not state the polarity of 3 & 4 !
As usual Chinese :"directives"??

[mactec54]

That is only when you use the supply for the load also,, the main issue is/was that the instructions do not state the polarity of 3 & 4 !
As usual Chinese :"directives"??

Does not have to say what the polarity is, the way it has been drawn is how the 12v+ would be applied the Relay switch is a good indication, load is normally switched this way, schematics / drawings are good

[Al_The_Man]

I am used to, and expect clear and precise instructions, perhaps that is foolish of me!
If in fact the supply input is polarity conscious then it behoves the manuf. to specify it .
There is nothing clear about that device manual that a little simple concise labeling or explanation would have explained right away.
Unfortunately it is something that one has to expect as normal from Asian sourced equipment :tired:

[mactec54]

I am used to, and expect clear and precise instructions, perhaps that is foolish of me!
If in fact the supply input is polarity conscious then it behoves the manuf. to specify it .
There is nothing clear about that device manual that a little simple concise labeling or explanation would have explained right away.
Unfortunately it is something that one has to expect as normal from Asian sourced equipment :tired:

There is very little that is not made in other countries, it just depends more on the manufacture, whether it is just a hole in the wall back yard place or a brand name as to the quality and presentation of the product, if you buy cheap then there may be some head scratching.