One penny touch probe and 2 touchplates

[rjreese29]

Hi,

I built the 'one penny touch probe' and it has the following circuit:
www.brusselsprout.org/cnc/1p-probe/
It works real well and I look forward to using it more with msm. I am would also like to setup the two touchplate system as posted in the manual.

Herein lies the issue, I am not that good with electronics, so I need some clarifications made. I bought a hex inverter and have partially bread boarded it up based on the most complete diagram I have seen posted on this site:
calypsoventures.proboards.com/index.cgi?board=msmsupport&action=display&thread=124

Would it be possible to hook this 3 wire probe to this two plate system? I guess I am a bit confused by this.

Any help would be greatly appreciated.

Thanks
Rob

[DaveCVI]

Hi,
I took a quick look at the "one penny probe" and noticed that the output line from the probe is an "active low" signal. This is different than most other probes which are "active high" - that's good news for you as it will make interfacing the "one penny probe" easier.

You will probably not need to build the inverter circuit - the inverter is used to change an "active high" probe line into an "active low" signal so that multiple active low signals can be connected to the breakout board probe input connection.

Since the one-penny is already active low, with any luck you will just be able to connect the the one-penny probe output and the two touch plates directly to the breakout board input. Effectively, this is wiring the probe and the touch plates in parallel to the input pin. This should work depending on the pull up resister etc at the BoB input. Some BOBs need an external resister, some have it already built into the BOB.

I'd give it a try as the first step, then check that triggering the probe and touching each of the plates to a tool each cause the probe LED to go green in MSM. If that works, you will be all set.

If all is fine, just forget about the inverter circuit etc.

In summary, for an active low probe:
1) tap +5v to power the probe.
2) connect probe output to BOB probe input pin
3) connect probe gnd to BOB input gnd.

Dave

[rjreese29]

Thank you a bunch Dave. !!