Post by thread:[EE] need suggestions for low-force double pole sw

As the subject indicates, I am looking for a low-force switch. The switch serves as an interlock for a bed-of-nails tester: The tester has a plastic cover with a protruding pin. The pin actuates the switch when the cover is closed. It is important that the switch be a double-pole type so it breaks both sides of the line. Picture can be provided if it helps. The problem I'm running into is that the only double-pole switches I've found are 15+ Amps and require a significant amount of force to actuate. The plastic cover's weight is not enough to actuate the current switch that was selected. In this case, a Cherry E20-series with a lever, specified actuating force is 312 gram. (Of course, force should be measured in Newton, not gram, but I didn't write the datasheet) I measured the effective weight of the cover at 120 grams (the cover is on a hinge. 'effective' in this case means the weight seen by the switch). So the switch needs to be activated with less than 1.18N The tester will be used on both AC and DC powered boards. So i need a switch that is rated for 3A 250V, and one that can handle around 8A at 15V. Would be a bonus if the same switch could be used. Doesn't matter if it's a plunger or lever style. Must be double-pole (doesn't have to be double-throw. a NO-type would do). Must be activated by less than 120 grams/1.18N. Any suggestions or pointers would be appreciated. One possibility is taking two single-pole switches and linking them mechanically, but that seems less reliable/more troublesome than a single switch. Phil Eisermann Electronics Engineer Ridge Tool Co (440)329-4680

>The tester will be used on both AC and DC powered boards. >So i need a switch that is rated for 3A 250V, and one that >can handle around 8A at 15V. Would be a bonus if the same >switch could be used. Doesn't matter if it's a plunger or >lever style. Must be double-pole (doesn't have to be >double-throw. a NO-type would do). Must be activated by >less than 120 grams/1.18N. Why not use a suitable relay operated by a microswitch? It sounds like whatever supply drives the UUT should have enough spare power for a relay coil.

> Any suggestions or pointers would be appreciated. One possibility is > taking two single-pole switches and linking them > mechanically, but that > seems less reliable/more troublesome than a single switch. use a low-force SPST switch and a relais? Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

> > > The tester will be used on both AC and DC powered boards. So i need a > switch that is rated for 3A 250V, and one that can handle around 8A at > 15V. Would be a bonus if the same switch could be used. Doesn't matter > if it's a plunger or lever style. Must be double-pole (doesn't have to > be double-throw. a NO-type would do). Must be activated by less than 120 > grams/1.18N. High current switches typically require larger contact force, and therefore more actuation force. I think you need to export that function to a relay. Also, do you really want to bring line current up to that point?

peiserma@ridgid.com wrote: {Quote hidden}>As the subject indicates, I am looking for a low-force switch. The >switch serves as an interlock for a bed-of-nails tester: The tester has >a plastic cover with a protruding pin. The pin actuates the switch when >the cover is closed. It is important that the switch be a double-pole >type so it breaks both sides of the line. Picture can be provided if it >helps. > >The problem I'm running into is that the only double-pole switches I've >found are 15+ Amps and require a significant amount of force to actuate. >The plastic cover's weight is not enough to actuate the current switch >that was selected. In this case, a Cherry E20-series with a lever, >specified actuating force is 312 gram. (Of course, force should be >measured in Newton, not gram, but I didn't write the datasheet) I >measured the effective weight of the cover at 120 grams (the cover is on >a hinge. 'effective' in this case means the weight seen by the switch). >So the switch needs to be activated with less than 1.18N > >The tester will be used on both AC and DC powered boards. So i need a >switch that is rated for 3A 250V, and one that can handle around 8A at >15V. Would be a bonus if the same switch could be used. Doesn't matter >if it's a plunger or lever style. Must be double-pole (doesn't have to >be double-throw. a NO-type would do). Must be activated by less than 120 >grams/1.18N. > >Any suggestions or pointers would be appreciated. One possibility is >taking two single-pole switches and linking them mechanically, but that >seems less reliable/more troublesome than a single switch. > >Phil Eisermann >Electronics Engineer >Ridge Tool Co >(440)329-4680 > > > Mount a piece of metal than will bring a magnet near a reed switch. The current thru the reed will be very small, but is enough to actuate a sturdy DPST relay. --Bob -- Note: To protect our network, attachments must be sent to .....attachKILLspam@spam@engineer.cotse.net . 1-520-850-1673 USA/Canada http://beam.to/azengineer

piclist-bounces@mit.edu wrote: >> The tester will be used on both AC and DC powered boards. So i need a >> switch that is rated for 3A 250V, and one that can handle around 8A >> at 15V. Would be a bonus if the same switch could be used. Doesn't >> matter if it's a plunger or lever style. Must be double-pole >> (doesn't have to be double-throw. a NO-type would do). Must be >> activated by less than 120 grams/1.18N. > > > High current switches typically require larger contact force, > and therefore more actuation force. I think you need to > export that function to a relay. it sounds like that's the right fix in this case. I like the reed-relay (or a prox. sensor) triggering a larger relay. > Also, do you really want to bring line current up to that point? well, no. But the wiring is all internal, away from human hands. There's a hole in the case for the pin. The switch is inside the case, also. Thanks for the suggestions. Will have to check with the designers how much room is left.

>-----Original Message----- >From: piclist-bouncesKILLspammit.edu On Behalf Of .....peisermaKILLspam.....ridgid.com >Sent: Wednesday, February 22, 2006 11:09 AM > <snip> > >The problem I'm running into is that the only double-pole switches I've >found are 15+ Amps and require a significant amount of force to actuate. >The plastic cover's weight is not enough to actuate the current switch >that was selected. In this case, a Cherry E20-series with a lever, >specified actuating force is 312 gram. (Of course, force should be >measured in Newton, not gram, but I didn't write the datasheet) I >measured the effective weight of the cover at 120 grams (the cover is on >a hinge. 'effective' in this case means the weight seen by the switch). >So the switch needs to be activated with less than 1.18N <snip> How about adding a 250g lead weight to the cover at the pin that should operate the 312g switch reliably. Another thought is to use a spring loaded hinge on the cover to give the cover more force. Paul

piclist-bounces@mit.edu wrote: >> -----Original Message----- >> From: EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu On Behalf Of peisermaspam_OUTridgid.com >> Sent: Wednesday, February 22, 2006 11:09 AM >> > <snip> >> >> The problem I'm running into is that the only double-pole switches >> I've found are 15+ Amps and require a significant amount of force to >> actuate. > > How about adding a 250g lead weight to the cover at the pin > that should operate the 312g switch reliably. yeah, that was a thought, but was thought to be lacking aesthetics. > Another thought is to use a spring loaded hinge on the cover to give > the cover more force. now that sounds potentially promising. Nice idea!

> Of Bill & Pookie > Sent: Wednesday, February 22, 2006 10:41 PM > > Combining the micro switch and the relay, have the "protruding pin" push > down the movable contact on the relay instead of the coil pulling it down. > > Pookie There are relays made with "push-to-test" buttons built-in that mechanicaly move the relay "wiper" contacts. We use them here. An example is a SongChuan 703XBM - DPDT unit rated for 10A @ 120Vac. I can't seem to locate a good picture. The relay is about 1" x 1" X 2" (We call them ice cube relays since they are in clear plastic cases and look a little like ice-cubes). The test button is about 1/8" dia and sticks out from the case about 1/8". I don't know the actuation force needed on the test button though. I suppose I could measure it if you're interested. I'm sure other relay people make similar units. Maybe as Pookie suggest, you could have the pin on your tester simply push the test button on the relay - simple solution. -- Mark P.S. Hey peisermann - I see you are in the 440 area code - you must be nearby. I work in Parma, OH.