ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
"Esoteric" countries and their wiring practices?
by Texas_Ranger. 04/20/19 07:00 PM
Norwegian power?
by Texas_Ranger. 04/20/19 06:27 PM
Welded Copper Connections
by gfretwell. 04/19/19 04:46 PM
Israel
by annemarie1. 04/18/19 02:35 PM
Water heater calculationsSo when I count calculati
by watersparkfalls. 04/13/19 12:43 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 7 guests, and 10 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Capacitive Proximity Switch #177445
05/02/08 11:40 PM
05/02/08 11:40 PM
B
BigJohn  Offline OP
Member
Joined: Mar 2004
Posts: 391
Boston, MA
I need a hidden deactivation switch for a security system. I'm thinking of using a capacitive proximity sensor hidden behind a thin, non-metallic object that will activate a relay when a hand is passed over the object.

I've never worked with prox. switches before. It appears that most of these switches use a transistor for switching. Are these traditionally digital or analog outputs? Will putting a barrier in front of the switch cause it to constantly conduct some amount of current to the output (maybe in relationship to the distance of the object from the sensor)? Or do most of these have a threshold value for "on" or "off"?

Any help would be much appreciated.

-John

Tools for Electricians:
Re: Capacitive Proximity Switch [Re: BigJohn] #177463
05/03/08 10:52 AM
05/03/08 10:52 AM
T
twh  Offline
Member
Joined: Mar 2004
Posts: 947
Regina, Sask.
The ones I'm most familiar with are a two-wire switch. Typically, they would provide an input to a PLC, but I've used them to switch a small relay.

Put a barrier in front of it and it will change states very quickly. The distance is adjustable. Metal is quite easy to calibrate, grain is harder to calibrate and needs to be in direct contact, and a hand - I've never had a bin full of hands, but I'm quite sure that I've tripped them with my hand.

Re: Capacitive Proximity Switch [Re: BigJohn] #177513
05/05/08 08:55 AM
05/05/08 08:55 AM
L
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Most prox switches I have worked with have a sensitivity adjustment. Metal sensing prox switches would work if the user wears a ring or holds keys or a tool up to the surface.

Larry C


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
HCE727
HCE727
Delaware County, PA, USA
Posts: 186
Joined: November 2005
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
254,521 Are you busy
190,760 Re: Forum
180,480 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.020s Queries: 15 (0.004s) Memory: 0.9518 MB (Peak: 1.0768 MB) Zlib enabled. Server Time: 2019-04-22 06:16:03 UTC