Touch probe woe's

**Smokie555** · 28-01-2023

This is just the info I need guys to get this thing working. Thanks to both of you for the time. I've just gone on a weeks holiday so won't be able to try this stuff until I get back but it will give me lots to think about until then. Cheers Ross

**Smokie555** · 30-01-2023

Just be looking at IRLZ34N online John, looks like a great solution. Just not sure how I power the probe, does it need to be from the Gecko's 48v supply and if so what is the best way to achieve this? If its ok to run it off a 5v USB supply or a 12v wall wart and do I need to connect the earths of the two supplies?

Cheers
Ross

**m_c** · 28-01-2023

Oops, I never realised that diagram had a transistor part number on it.
I just used the first online circuit diagram creator I found, and picked the NPN transistor. I did delete the resistor value, but never noticed the transistor had a part number.

The other option would be a micro-relay.
I've used DIP packaged relays in the past. Something like this - https://uk.rs-online.com/web/p/solid...relays/4801188 (that's just the first one I found)

**Smokie555** · 29-01-2023

never seen a micro relay! Sounds nice and simple so I may try that, cheers

**JohnHaine** · 29-01-2023

I would be slightly wary of a relay (assuming that it's electromagnetically operated) because of the possible extra delay.

**m_c** · 29-01-2023

Originally Posted by JohnHaine

I would be slightly wary of a relay (assuming that it's electromagnetically operated) because of the possible extra delay.

For that one I linked to, typical turn on time is 0.1ms, and turn off 1ms.

On a typical home brew machine, those times are going to be negligible in the grand scheme of things.

**JohnHaine** · 29-01-2023

It is actually a "solid state relay" so may be similar to what you were trying to use anyway.

**Smokie555** · 29-01-2023

That tiny solid state relay sounds fast enough for me if it works, looking at John's transistor circuit its clear my wiring of the mosfet setup was all wrong. The input voltage on the gecko pin is 12v but I will check the current when I get back. I doubt it will be much as the microswitches for my limit switches on the other 3 gecko inputs would probibly arc a bit. All good stuff

**JohnHaine** · 30-01-2023

Use an old phone charger with USB output, butcher a USB lead to get at the power conductors. Yes you MUST connect the earths. Probe is specced for 5V I think so you should use that.

**Smokie555** · 05-02-2023

Well isn’t it funny the total pleasure a switching LED in Mach3 can bring!

Arrived home from the holidays and made up the circuit below on a bread board and what do you know it works!!

Thanks a million m-c and John for sorting this out for me. I had to uncheck the active low setting in Mach3 to have it work the correct way around but I’m sure I can add my 4011 gate IC to invert this signal on the touch probe so both my touch probe and Z tool height plate work with the same Mach settings and the same 2.1mm plug jack on my panel, if not I’ll just live with having to switch the active low setting depending on which probe I’m using. Thanks again for your patience help and advice, and look forward to making a nice printed circuit of this for the finished item.

Cheers