Ohmic enable relay lopgic

rodw wrote: [quote="bevins" post=144256
I don't have a thcad-5. I just have thcad. Is there firmware on the thcad and up gradable to thcad5? lol,
?

I was thinking later that if you had a THCAD-10 spare, a 48 Volt isolated power supply is the same price as the 24 volt one I used. A 470k resistor would set the full scale to 52 volts or a 4.52k resistor would give full scale of 50.2 volts. Either would be perfect![/quote]

I could get another thcad and get a 48volt PS, but will the old way work? I already have everything. I got the isolated 24v power supply and relays and a thcad.

Whats the major advantages to the supercharged THC?

You can set a THCAD10 to 24V full scale with a 140K series resistor
(I would use 140K 1/2 W or two 69.8K 1/4 W in series)

PCW wrote: You can set a THCAD10 to 24V full scale with a 140K series resistor
(I would use 140K 1/2 W or two 69.8K 1/4 W in series)

But you guys are talking another thcad? One for thc and other for ohmic sensing?

Bevins, yes, I posted seperately about our experiments here
forum.linuxcnc.org/plasma-laser/37311-hy...-to-do-ohmic-sensing

So I just need to order another thcad. I may give this a try. Although I still do not know the benefits this gives over the other scenario other than better isolation?

This should be much more sensitive and less prone to fail, even on very dirty material.
It needs very little current to pass through it for it to register a change in resistance and subsequently trigger a signal.

Tommy, I think so. This is a plot I just did of an ohmic sense event. Pin to watch is ohmicsense.ohmic-on which is the probe signal. But the blue plasmac probe follows it as well



Here we turn the signal on at 18 volts and off at 5 volts. Plasmac probes back very slowly until it breaks contact so the off threshold is the important one and you can see its not triggered until all the noise subsides. I think it would be interesting if you set a low on threshold and smashed the probing at high velocity to speed up job cycle times.

I am getting a spurious probe signal reported by Plasmac on the first probe after opening a new file. I suspect either Phill or I are not setting a default value correctly. It does not bother plasmac, it still continues but I need to look further.

Stop already........ I'm ordering another thcad....

the probe signal is very clear
so no bouncing at the peek hole

bevins wrote: Stop already........ I'm ordering another thcad....

Santa gona be busy dis year !!!