Hypersensing with THCAD - better way to do ohmic sensing

tommylight wrote: Hmmmm that is new to me, thank you PCW.
I was under the impressions that the probing is switched off before firing the torch.
Adding a relay will solve that issue.
Now i have to wonder, if the probing THCAD is on all the time, the use of another THCAD seems redundant.
Will think about it a bit, while waiting for my THCAD's to arrive.

Yes the arc voltage is seen by the ohmic probe sensor.
I don't think a THCAD calibrated to read the arc voltage will be sensitive enough to read a 24v (or even 48V) voltage.
One of the advantages of this circuit is that it removed all relays and additional components. IF you are going to add them back, it makes no sense to use the THCAD.

Remember, we are talking about a use case here that is an issue for any ohmic sensing circuit.

I think its premature to be modifying the circuit at this stage as we have not exhausted software solutions.

Water is not a software issue, and there is nothing in software to fix that.
And i do get that using relays will defeat the purpose of THCAD, so back to the drawing board.
Also i am sure it is an issue as i have seen it used only on downdraft tables, never on water tables. But that will not stop us from trying to get around it and find something usable and reliable. Oh i miss my THCAD's.........

An interesting quote from John in this post

I know there has been a lot of discussion at times about "false" triggering of ohmic sensing. I can say with certainty that I have never had a problem with this that was a true false trigger. Yes, I have probing errors all the time but they are always caused by a flooded torch end or dross stuck in the torch end. So the probing errors are always cause by a true shorted torch which is why you check for that condition before the start of probing..

phillc54 wrote: An interesting quote from John in this post

I know there has been a lot of discussion at times about "false" triggering of ohmic sensing. I can say with certainty that I have never had a problem with this that was a true false trigger. Yes, I have probing errors all the time but they are always caused by a flooded torch end or dross stuck in the torch end. So the probing errors are always cause by a true shorted torch which is why you check for that condition before the start of probing..

I'm pretty sure that is why John made you add the probe test button to the GUI so he could check for a shorted torch before running a job. Press the button and if the ohmic light came on, he had a problem.

I've made some progress recoding using a moving average to hopefully account for the noise observed which worried me.

tommylight wrote: Water is not a software issue, and there is nothing in software to fix that.

Tommy what about softwater instead of software????

rodw wrote:

phillc54 wrote: An interesting quote from John in this post

I know there has been a lot of discussion at times about "false" triggering of ohmic sensing. I can say with certainty that I have never had a problem with this that was a true false trigger. Yes, I have probing errors all the time but they are always caused by a flooded torch end or dross stuck in the torch end. So the probing errors are always cause by a true shorted torch which is why you check for that condition before the start of probing..

I'm pretty sure that is why John made you add the probe test button to the GUI so he could check for a shorted torch before running a job. Press the button and if the ohmic light came on, he had a problem.

Exactly...