N
Noway2
- Jan 1, 1970
- 0
During a design review yesterday, a question was posed to me about
whether or not the customers will need to use gold contacts on the
switches that connect to our system. In response, I have been
searching for some guidelines as to when gold contacts are required. I
have found a lot of information discussing mechanical operation of
contacts, wetting current, oxide build up, etc, but have not found
anything providing some "rule of thumb" recommendations.
In this instance, the design is as follows:
Our design contains (user) inputs implemented with opto isolators. The
circuit design is such that we provide a 12V signal and ground and the
user provides a switch closure to flow current from the 12V supply
through the opto's diode and a current limiting resistor. I can't
control how far away the switch will be located or what type of switch
the customer will use. I can control the size of current limiting
resistor, which I present have set as 1.2K for 10mA of current @ 12V
through the opto.
My question is does anyone have any rule of thumb that says, generally,
under X volts or X amps, gold contacts are required. I understand that
this is a vague question and an exact answer depends on the
application, environment, etc, and information I don't (and won't) have.
whether or not the customers will need to use gold contacts on the
switches that connect to our system. In response, I have been
searching for some guidelines as to when gold contacts are required. I
have found a lot of information discussing mechanical operation of
contacts, wetting current, oxide build up, etc, but have not found
anything providing some "rule of thumb" recommendations.
In this instance, the design is as follows:
Our design contains (user) inputs implemented with opto isolators. The
circuit design is such that we provide a 12V signal and ground and the
user provides a switch closure to flow current from the 12V supply
through the opto's diode and a current limiting resistor. I can't
control how far away the switch will be located or what type of switch
the customer will use. I can control the size of current limiting
resistor, which I present have set as 1.2K for 10mA of current @ 12V
through the opto.
My question is does anyone have any rule of thumb that says, generally,
under X volts or X amps, gold contacts are required. I understand that
this is a vague question and an exact answer depends on the
application, environment, etc, and information I don't (and won't) have.