So, a 1000+EUR simple switch? Really? - Page 1
Forum section: electronics / general

author: daqq
author_rank: Super Contributor
timestamp: February 16, 2017, 02:15:21 pm
content: OK, I have to ask,What the hell:http://uk.farnell.com/honeywell/25et1tf/toggle-switch-spdt-4a-28vdc/dp/2525439?...is it magic?

author: Mashpriborintorg
author_rank: Regular Contributor
timestamp: February 16, 2017, 02:22:20 pm
content: Seems to be aircraft grade, I have a few similar things in my aircraft parts collection. I wish I could resale some of my parts at their original pricetag...

author: cowana
author_rank: Frequent Contributor
timestamp: February 16, 2017, 02:23:18 pm
content: QuoteAlso something rather special - I suspect these are manufactured by hand in very small quantities!

author: ConKbot
author_rank: Super Contributor
timestamp: February 16, 2017, 02:23:30 pm
content: Did you look at the datasheet?http://www.farnell.com/datasheets/2145064.pdfNot a "simple" switch. And its meant for military aircraft, so 2 significant cost adders there. Not saying it is really worth that much, but guaranteed quality on a low production volume item isn't cheap.

author: FrankBuss
author_rank: Unknown
timestamp: February 16, 2017, 02:31:28 pm
content: Did I miss it or doesn't the datasheet specify the mechanical life? Even some cheap one dollar switches specify this, e.g. first one I found:30,000 make and break cycles.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 16, 2017, 04:01:56 pm
content: Really not simple. Did you notice the remotely activated hold on feature? The nitrogen filled hermetic chamber (explosion safety)? The locking feature on the toggle? Conformance to a MIL standard?And finally, if farnell has the part number right, it is a custom configuration of the ET series, not listed on the Honeywell data sheet.But other than that it is just like any other SPDT you can find in your parts bin.

author: grumpydoc
author_rank: Super Contributor
timestamp: February 16, 2017, 04:31:48 pm
content: It's actually quite neat.Given the intended military use it is mildly amusing that they offer discount prices up to 3000+ units - a snip at just under £700 each or £2,08,940 ex VAT for the whole order.

author: ConKbot
author_rank: Super Contributor
timestamp: February 16, 2017, 05:21:31 pm
content: Quote from: FrankBuss on February 16, 2017, 02:31:28 pmMinimum switch life is probably dictated in SAE AS55941 that the switch complies with. The only time they would specify contact life would be if it greatly exceeded the spec while still fully complying with it otherwise. "Look, buy these, much longer lasting than other switches meeting spec" etc.

author: ZeTeX
author_rank: Frequent Contributor
timestamp: February 16, 2017, 08:40:42 pm
content: One switch to rule them all.It's a special switch intended for special applications..is it wroth £959.81? not really in terms of the manufacturing costs but when you only need 5 switches for military aircraft that cost billions it is not that expensive at all.

author: amyk
author_rank: Super Contributor
timestamp: February 17, 2017, 10:17:32 am
content: Switches with solenoids to hold them have been around for a long time; one application that comes to mind is car window defrost switches.Quote from: ConKbot on February 16, 2017, 02:23:30 pmThe disclaimer on the last page saysQuote

author: FrankBuss
author_rank: Unknown
timestamp: February 17, 2017, 10:30:00 am
content: Quote from: amyk on February 17, 2017, 10:17:32 amRight, $1k is a bargain, safety critical switches cost more.

author: james_s
author_rank: Super Contributor
timestamp: February 17, 2017, 08:30:16 pm
content: Quote from: amyk on February 17, 2017, 10:17:32 amNot saying they don't exist, but I've never seen one that works like that. My car rear window defroster controls are momentary switches with an electronic timer circuit inside. The switch itself does not mechanically disengage when the time expires.

author: rrinker
author_rank: Super Contributor
timestamp: February 17, 2017, 09:26:18 pm
content: Maybe way back. My current oldest vehicle is a 1993, and it is momentary with an electronic timer, not electromechanical. The never been used cigarette lighter on the other hand...

author: james_s
author_rank: Super Contributor
timestamp: February 17, 2017, 09:40:41 pm
content: I have a '77, a '84 and my newest car is '87, they all have electronic timer controls.Maybe back in the 60s-70s it was different, likely a thermal timer though similar to the cigarette lighter you mention rather than a solenoid.

author: Vtile
author_rank: Super Contributor
timestamp: February 17, 2017, 11:03:07 pm
content: Have you taken a peak of the prices of the 2x12 rotary switches. I though I make a cheap kelvin divider box ....

author: JoeN
author_rank: Frequent Contributor
timestamp: February 18, 2017, 09:48:52 am
content: Quote from: ConKbot on February 16, 2017, 02:23:30 pmThe quality of this product is so great that the manufacturer feels they need to add this caveat:

author: igendel
author_rank: Frequent Contributor
timestamp: February 18, 2017, 10:33:49 am
content: Quote from: JoeN on February 18, 2017, 09:48:52 amStill good for military aircraft... e.g. as a bomb-releasing switch

author: SeanB
author_rank: Super Contributor
timestamp: February 18, 2017, 12:23:05 pm
content: That is because it is not designated as a safety switch. Those need double acting contacts, with a 3mm separation between each contact when open, and 5mm between contact units. They also have to open with any single contact welded fast to that safety distance. These probably only have a 2mm gap and are single contact, so not safety units.Ordinary V3 microswitch is a few cents, but the same size V3 microswitch in a safety switch rated version is a few dollars each, and is then either normally closed or normally open. The ones used in microwaves as door safety switches are not safety switches, but the ones you find in large industrial equipment ( though there often the switch is a lot larger as it has to be both ATEX, EEX and IP68 rated as well) are almost always safety ones. There you have the basic switch body, with the internal 3 connections and a PE terminal, and then you get assorted head units that allow you ti make up all the variants of mechanical input you want, from sensitive wire to roller, cam and simple angle.Then you get into the real safety switches, that are either for rope safeties, pull emergency stops or cabinet interlocks. those also come with a certificate for each switch.

author: ConKbot
author_rank: Super Contributor
timestamp: February 19, 2017, 07:24:40 pm
content: Quote from: SeanB on February 18, 2017, 12:23:05 pmYou cant expect everyone to know the difference between "Safety" and actual safety.Ive worked with a rate table that could be programmed with a ramp up and down acceleration. Opening the door or hitting the E-stop would make it ramp down at the maximum programmable rate. The only problem with commanding a PID controller to ramp down is that it will still apply power to maintain that ramp. I could open the door, grab the empty table, stall motor, let go of it and it would quickly snap back up to speed (so much for safety, or limiting load on the table by enforcing the ramp) and continue the ramp back down. E-stop switch and door sensor were just wired to the controller card. ( Name and shamehttp://agdavis.com/Though it looks like they dont advertise any rate table models anymore )This was before even allowing for potential failures.

author: james_s
author_rank: Super Contributor
timestamp: February 19, 2017, 08:24:55 pm
content: You see the same warnings with parts about using them in medical or life support devices. It's not that they won't work just fine, but they haven't been tested and certified specifically for that purpose. You're paying for the testing and certification when you buy the expensive medical grade part, the part itself may be no better than the non-certified part. The warnings mostly come down to lawyers, it's the same reason packages of peanuts are printed with a warning that they "may contain nuts", well duh.