Robust connectors, low frequency signals, needs to be able to deal with dirt  et - Page 1
Forum section: electronics / projects

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 21, 2018, 11:50:06 am
content: I build airsoft props every now and then for a friend of mine who runs pretty large events on a weekly basis.For one of the next props, we want to have a device that needs to be transported around and then plugged in to activate a terminal (details really don't matter that much).In order to easily detect the connection is made I just wanted to have the device output a simple square wave at a certain frequency (on the order of a few kHz) such that it can be detected, and perhaps different devices can be used (say each team gets such a device, and to recognise what team it is, a different frequency is used for each).This means I need a connector to interface the two, which is what I am stuck on now.These props need to take a beating. You can tell the guys to "be gentle" as often as you want, but they will forget everything you told them when they are in the heat of the moment and adrenaline is flowing.Since the events take place in horrible weather in forests, it needs to be able to take mud, water, whatever and still work. It doesn't need a tonne of cycles - even a few hundred is more than enough since it might be plugged in and out one or two times every weekend, and once it is used for a few dozen times it will no longer be used anyways since the players will want new props.Any suggestions? Something that "looks" military/industrial-like is a bonus. I've thought about N-connectors (that I can get off of aliexpress for cheap) but I think they won't be able to take enough regarding the mud/dirt part.It's allowed to be a big metal part, this is gonna be a big box. Just needs to not cost 500 bucks for a connector - maybe 10-15 Euro's per connector is a good start? But if that is unreasonable I can always look at alternatives.

author: Twoflower
author_rank: Frequent Contributor
timestamp: January 21, 2018, 12:05:52 pm
content: How about some kind of 'fake' connector? Use an RFID transponder in the token, build some case around it (e.g. a tube). The player has to put this tube into the counterpart. In this counterpart the receiver is located. This can be build extremely robust and no contacts that might suffer handling.Otherwise look for military grade connectors. But they might get big and require some time to 'operate'. Like unscrew a lid. But you're not sure the lid is fastened afterwards...Just an idea ;-)

author: max_torque
author_rank: Super Contributor
timestamp: January 21, 2018, 01:03:48 pm
content: I'd go with a hall effect switch in the terminal, and a "magnetic" key to enable it. Team just presses "key" against the terminal, no electrical contact required!If you want different teams to be recognised, just use more than one switch. ie two switches gives you an ID for 3 teams, 3 switched for 8 teams etc

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 21, 2018, 01:15:22 pm
content: It needs to be a connector. The reason for this is that we might in the future want to switch to more complex capabilities, and that the device itself has to be big, and itself contain a certain amount of electronics. The current idea is that the thing they need to carry arround is some kind of sensitive chemical or whatever in a carrying system, and that it is very shock sensitive. This way they need to work together to protect the guy carrying because he can't shoot back or run and so on.If the device experiences to great a shock, it is "disarmed" and they need to go back to their base camp, where they will have another device that can "arm" it again.So while I appreciate the outside-of-the-box thinking, I have thought this through a few times and talked about it with the guy I'm building it for and we agree that a connector is the way to go.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 21, 2018, 01:20:05 pm
content: RFID/NFC would seem to be a no-brainer here,unless you really need to carry power over the interface.If the amount of data is small, you don't need to go full NFC protocols - a couple of inductors can easiily make a simple data link.

author: SeanB
author_rank: Super Contributor
timestamp: January 21, 2018, 01:23:45 pm
content: If not RFID how about a simple magnetic switch in the base and a magnet, or a series of magnets to give some coding, to activate it. The socket could be as simple as a depression the unit is placed into, like a puck, and use some small high strength neodymium magnets to activate the reed relays. You could also use hall switches if you want a more rugged version.You could also have the reverse to activate the puck, a magnet to switch the puck into an active state so that a magnetic loop could transmit data to the base, or the other way round using simple coupled loops to handle the data. Microcontroller in both sides to handle the data, and a lithium cell pack for long term power supply.That way you have rugged and no exposed connectors, aside from possibly a sealed screwed on cover that hides a battery charging socket on the puck.

author: jeremy
author_rank: Super Contributor
timestamp: January 21, 2018, 01:29:30 pm
content: Assuming you are really not interested in doing RF, I would suggest M8 or M12 connectors (it's a standard industrial connector, google it). They come in IP68, and in small volume (~50 units) are about 2-3 USD from Chinese sellers. You can also get nice ones from the usual suspects (TE, Phoenix, etc) at Digi-Key/mouser. Cables are easily found off the shelf too.They won't work when muddy, but you can just wash them out with water.

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: January 21, 2018, 01:36:50 pm
content: Trymagnetic Rosenberger onesThey are IP67 and can be yanked out and self-connect with a mighty satisfying clank.Leo

author: 001
author_rank: Super Contributor
timestamp: January 21, 2018, 01:42:16 pm
content: try simple 1/4 inch jack

author: The Soulman
author_rank: Super Contributor
timestamp: January 21, 2018, 02:11:32 pm
content: I was going to suggest the original harting product but looking at their website I couldn't find the appropriate product withing 3 minutes.So here is a clone:https://www.aliexpress.com/item/MK-HE-006-2D-European-standard-side-entry-16A-400V-500V-industrial-harnesses-wire-Harting-heavy/32623483214.html?spm=2114.search0204.3.29.f279431u7rDc4&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10068_10344_10342_10343_10340_10341_10084_10617_10083_10616_10304_10615_10307_10301_10313_10059_10534_100031_10604_10103_10142,searchweb201603_1,ppcSwitch_5_ppcChannel&algo_expid=f99504cc-11d4-4624-bc0b-df3a858733d5-4&algo_pvid=f99504cc-11d4-4624-bc0b-df3a858733d5&priceBeautifyAB=1

author: tpowell1830
author_rank: Frequent Contributor
timestamp: January 21, 2018, 02:23:01 pm
content: BNC connector

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 21, 2018, 02:23:45 pm
content: Quote from: jeremy on January 21, 2018, 01:29:30 pmThat could be a potential score. Will have to see what I can find from China and such. Sticking to an available standard sounds nice since this means that if we have breaking we can always get replacement connectors etc, as well as reuse cables more easily and have extras.Quote from: Leo Bodnar on January 21, 2018, 01:36:50 pmThose look cool, will have to check the pricings on those. Knowing Rosenberger, it won't be cheap tho.Quote from: 001 on January 21, 2018, 01:42:16 pmI have quite some experience with 1/4 inch jacks as a guitarist, and have to say that they are just too fragile. I've broken quite a few already, and most of the jacks require a real opening vs a sealed connector, which means any dirt or grime could easily run into the system. That does remind me of XLR though, which might also be worth considering.Quote from: The Soulman on January 21, 2018, 02:11:32 pmNow these are awesome. That really has that heavy-duty military look I am going for in this prop. I think I'm going to order some to try straight away!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 21, 2018, 02:44:39 pm
content: Quote from: 001 on January 21, 2018, 01:42:16 pmor XLR

author: Buriedcode
author_rank: Super Contributor
timestamp: January 21, 2018, 03:03:32 pm
content: Quote from: mikeselectricstuff on January 21, 2018, 02:44:39 pmI'll second that. They're used on some pyrotechnic gear, and abused pretty badly, just like they are in the audio industry. Cheap, reliable, not sure how they would cope with mud though.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 21, 2018, 03:49:15 pm
content: Maybe a harting connector is something? It isn't 20 bucks, but it is a big sturdy metal connector.If you can find the right parts, you can have them in all angles and sizes you like.

author: kony
author_rank: Regular Contributor
timestamp: January 21, 2018, 05:53:43 pm
content: Weipu round connectors.https://www.tme.eu/en/katalog/weipu-connectors_112972/#They are very decent for the price, using them for both laboratory instrumentation and outside usecases.

author: iwtommo
author_rank: Contributor
timestamp: January 21, 2018, 10:03:53 pm
content: What about a car trailer connector? 7 pins, few amps per pin, and looking at the back of any muddy beat up transit pulling a trailer im constantly surprised they always work. They can be had with medal enclosures if youre worried about high fps bb strikes but i imagine they are cable mount only.https://www.ebay.co.uk/itm/231672818717

author: Niklas
author_rank: Frequent Contributor
timestamp: January 21, 2018, 10:08:10 pm
content: HDSCS-series of connectors from TE are used in several automotive applications. Sealed and available with 4, 6 or 8 ways and latching. Can be assembled either as pigtail or on bulkhead (rectangular cutout in the enclosure)

author: Someone
author_rank: Super Contributor
timestamp: January 22, 2018, 12:02:16 am
content: Quote from: TheUnnamedNewbie on January 21, 2018, 02:23:45 pmAny of those enclosed types of connectors will still clog with mud and be unserviceable, they rely on the use of end caps for field use which have to be manually removed and replaced. I can't recall and small connectors for manual handling with automated shutters/covers which would match your requirements but there is low tech solution. Blade type connectors are available with double sided entry and through their mating action push any foreign material out of the way, keep the voltages low and currents high and you can use them in wet conditions.