What is a "wet contactor"

Started by Bob Engelhardt December 18, 2017
An eBay listing for a electronic tachometer specifies that it's input 
can be a "wet contactor".  Is there a standard meaning for "wet contactor"?

Thanks,
Bob
In article <p18ufl013tt@news7.newsguy.com>, BobEngelhardt@comcast.net 
says...
> > An eBay listing for a electronic tachometer specifies that it's input > can be a "wet contactor". Is there a standard meaning for "wet contactor"? > > Thanks, > Bob
Dry contacts are when there is no electrical current/voltage and the wet ones are when you have voltage/current. For a tach , most of the old style would have the wires across the points. There would also be the car electrical system connected to the points. That would make them wet. If (probably never found) there were a seperate set of contacts that opened and closed as a shaft on the engine turned and not connected to the electrical circuit of the car, they would be dry contacts. While not useful in this case, some contactors/relays/switches will have mercury wetted contacts.

"Bob Engelhardt" <BobEngelhardt@comcast.net> wrote in message 
news:p18ufl013tt@news7.newsguy.com...
> An eBay listing for a electronic tachometer specifies that it's input can > be a "wet contactor". Is there a standard meaning for "wet contactor"?
In some cases it can mean mercury wetted contacts, but the term "wetted" is also used to describe when dry contacts carry sufficient current to break through any oxide or contaminants on the contact surfaces.
On 2017-12-18, Bob Engelhardt <BobEngelhardt@comcast.net> wrote:
> An eBay listing for a electronic tachometer specifies that it's input > can be a "wet contactor". Is there a standard meaning for "wet contactor"?
dry contacts is terminology used to describe contact frovided as part of a device that are ot connected to any internal circuit and singnal by chngeing from insulator to conductor, by extension wet contacts must be switching current I'm guessing that this wet/dry terminology is borrowed from hydraulics In an automobiles before crank position sensors became common the tachometer output would be taken from the ignition coil (where the points or electronic ignition connects). There'd be a programmabile divider to compensate for how many cylinders the engine has. -- This email has not been checked by half-arsed antivirus software
On 12/18/2017 12:42 PM, Bob Engelhardt wrote:
> An eBay listing for a electronic tachometer specifies that it's input > can be a "wet contactor". Is there a standard meaning for "wet contactor"? > > Thanks, > Bob
Once again I have not told the whole story :-( I was going to use this tach on my milling machine spindle, not my car. I think it works by pulsing a circuit between 2 of its connector pins. It also can be pulsed by " ... PNP or NPN proximity switch, HALL sensor". Does that help determine what the mean by "wet contactor"? Bob
On Monday, December 18, 2017 at 12:42:33 PM UTC-5, Bob Engelhardt wrote:
> An eBay listing for a electronic tachometer specifies that it's input > can be a "wet contactor". Is there a standard meaning for "wet contactor"? > > Thanks, > Bob
A french kisser!
On 2017-12-18, Bob Engelhardt <BobEngelhardt@comcast.net> wrote:
> On 12/18/2017 12:42 PM, Bob Engelhardt wrote: >> An eBay listing for a electronic tachometer specifies that it's input >> can be a "wet contactor". Is there a standard meaning for "wet contactor"? >> >> Thanks, >> Bob > > Once again I have not told the whole story :-( > > I was going to use this tach on my milling machine spindle, not my car. > I think it works by pulsing a circuit between 2 of its connector pins. > It also can be pulsed by " ... PNP or NPN proximity switch, HALL > sensor". Does that help determine what the mean by "wet contactor"? > > Bob
it seems that they bsically mean anything that generates a pulse every time the shaft rotates, what sort of sensor do you want to use? -- This email has not been checked by half-arsed antivirus software
On 12/18/2017 10:53 PM, Jasen Betts wrote:
> On 2017-12-18, Bob Engelhardt <BobEngelhardt@comcast.net> wrote: >> On 12/18/2017 12:42 PM, Bob Engelhardt wrote: >>> An eBay listing for a electronic tachometer specifies that it's input >>> can be a "wet contactor". Is there a standard meaning for "wet contactor"? >>> >>> Thanks, >>> Bob >> >> Once again I have not told the whole story :-( >> >> I was going to use this tach on my milling machine spindle, not my car. >> I think it works by pulsing a circuit between 2 of its connector pins. >> It also can be pulsed by " ... PNP or NPN proximity switch, HALL >> sensor". Does that help determine what the mean by "wet contactor"? >> >> Bob > > it seems that they bsically mean anything that generates a pulse every > time the shaft rotates, what sort of sensor do you want to use? >
I'd like to use a magnet on the spindle and a reed switch. It's about the most contamination proof. If the reed switch is "wet".
On 12/18/2017 12:42 PM, Bob Engelhardt wrote:
> An eBay listing for a electronic tachometer specifies that it's input > can be a "wet contactor". Is there a standard meaning for "wet contactor"? > > Thanks, > Bob
I asked this question of the (Chinese) seller, not expecting any real answer. I was not disappointed: "Really so sorry. I do not know what the problem is. I hope you can understand"
Bob Engelhardt wrote on 12/19/2017 1:21 PM:
> On 12/18/2017 12:42 PM, Bob Engelhardt wrote: >> An eBay listing for a electronic tachometer specifies that it's input >> can be a "wet contactor". Is there a standard meaning for "wet contactor"? >> >> Thanks, >> Bob > > I asked this question of the (Chinese) seller, not expecting any real > answer. I was not disappointed: "Really so sorry. I do not know what the > problem is. I hope you can understand"
Would you ask this question of the person operating the cash register at Home Depot? -- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998