Hi All!

I have an arduino cct I can use for simulating the "shorting" of NAMUR inputs (+/-) to provide a signal input, and it works well.

I was wondering if its possible to do this in a single, self-contained circuit, drawing power from the NAMUR +ve rail?

I have ideas of using a 555 to set the pulse frequency, but not sure where to start on the output, shorting of contacts part... drive a transistor off the trigger output possibly?

Any guidance really appreciated.

 

Oops, mods, can you please move this to the correct forum? Thanks

 

Here is the cct I have so far but it's not pulsing to the base of the BC546.
Sw1 should be continuous mode, frequency set by Sw3 position. Sw2 is for a single pulse.

Any help appreciated...