Dear Admin/Forum Members,

I have a requirement to logically "OR" two digital signals produced by two seperate Flow Switches, which is a 24Volt DC.
The output can be fall up to 15VDC from the nominal value of 24Volts DC.

A B Output
0 0 0
0 1 1
1 0 1
1 1 1

Please advice a suitable circuit design.

 

hi,
Have you considered using two diodes to build an OR gate.
E

 

You don't say what current is available from each of the input signals, and your statement about the output is not clear. What is the acceptable output voltage range for a logical "low" and what is the range for a logical "high"? How much current can each input signal source?

ak

 

Wire the switches in parallel. Use a resistor and zener to limit the output voltage -- if necessary.