Hall switch or momentary switch?

[beekeeper5]

Hello. For a canister dive light, would you recommend a hall switch where you turn on the light using a magnet or a simple momentary switch with a waterproof boot?

The dive light I'm planning to build will use DW's triple XM-L kit so the "switch" needs to be momentary and there will be a low, medium and high mode.

How easy or difficult is it to use a momentary with a hall switch?

The triple XM-L kit driver modes are:
Press (driver is off): Turns on the driver
Short press (driver is on): Turns off the driver
Press & hold: Changes mode

Thanks in advance.

 

[Codiak]

The hallsw will work fine for those functions.

The trade off is carrying a magnet or creating a hole an potential leak point.

Opinions vary.... I prefer not carrying magnets, but I navigate by compass more than most

 

[Packhorse]

A well chosen magnet mounted to the cannister will have no effect on a compass.

My magnet based switchs are rotary so you just twist the ring until the magnet aligns. But for a momentary system then you are probably better off with a spring loaded magnet.

But I think an option that may be better is a Piezoelectric.

 

[beekeeper5]

What's a spring loaded magnet? I was thinking of using TaskLED's Hallswitch with DW's triple XM-L kit. Otherwise, I would get a momentary switch with 350xfire's boot.

I'm on the fence on this one.

 

[Codiak]

The piezo is the best option in my opinion.

And as I've said before the magnet adds to my task loading... I never want to second guess myself or equipment while narced

 

[Codiak]

What's a spring loaded magnet? I was thinking of using TaskLED's Hallswitch with DW's triple XM-L kit. Otherwise, I would get a momentary switch with 350xfire's boot.

I'm on the fence on this one.

Forget the boot... Just drill a hole and tap the threads, stick a piezo switch in and use sealant in on the inside as well.
Cost vs hallsw is a wash...allied electronics has piezos cheap

 

[beekeeper5]

Forget the boot... Just drill a hole and tap the threads, stick a piezo switch in and use sealant in on the inside as well.
Cost vs hallsw is a wash...allied electronics has piezos cheap

Do you have a URL for the piezo you use?

 

[Klem]

My advice is you need to tread carefully here.

A driver that distinguishes between 'clicks' (short press) and 'presses' (longer press) limits your choice of switches when used underwater. A momentary piezo switch works well underwater however a standard piezo can never stay closed long enough for you to impart 'presses'...only 'clicks'. The solution is to use a 'prolonged piezo' which can stay closed for up to 6 seconds, as opposed to under 0.2 seconds for normal piezo's.

I've been making a couple of torches with a similar type driver recently and find for underewater use it is less than perfect to use a Hall switch. You have to carry a second piece of kit, the magnet around to operate it. My experience is the magnet needs to be strong and come at the torch in exactly the right spot to operate. You can do it reasonably well while sitting at your desk but after trying it on 2 dives I can tell you it's a lot harder trying to distinguish between clicks and presses with a magnet, having to use both hands to do it, and while being pushed around by the current. In the end you feel like turning it on and not wanting to play around with it until the end of the dive, which is a waste of the potential to turn it on and off, and use mode-changing whenever you want. I went with a prolonged piezo which is a one-handed job, much more precise (no mistakes) and no fear your compass will be influenced by this magnet hanging off you somewhere. Plus you can change modes simply and quickly without taking your concentration off the surroundings.

If you can work 'clicks' and 'presses' with a Hall underwater then you are a better man than me. What I reckon the Hall is good for are simple drivers, or HIDs. Simple 'click' on/off with one swipe of the magnet, or a torch like a HID which doesn't like to be turned on/off constantly and has no modes. Just turn on at the start of the dive, and off at the end.

A prolonged momentary is the 'Ferrari' of solutions but will set you back $50+, so it's not as cheap as a Hall.

Now... it's fair to say a normal momentary switch does not work in underwater torches because the pressure quicky builds up and forces it constantly on. Some years ago I was too ignorant to realise this and put a momentary on a canister with a thick rubber boot to waterproof it. It worked! and I was blissfully ignorant of the effect of pressure on switches until someone pointed it out. The rubber boot was stiff enough, along with the shape and how pressure acts on the shape to resist pressure so I could press it while underwater and it would spring back. I went no deeper than 20 metres from memory so I am unsure how something like this would work deeper. I might do an experiement to find out. . Point being, this is a cheaper solution than a prolonged piezo, with all the benefts and no disadvantages of the Hall...but...It might not work deeer than 20M and there's the risk of leakage through the rubber boot, which a Hall and prolonged piezo do not have (the piezo has the potential to leak where you cut the hole for it but you only have yourself to blame if that happens).

Pictures of the prolonged piezo on left, and the rubber booted momentary on the right (a starter button from an auto shop designed for boats)

Sorry for the essay but it is not as simple as it first seems.

Good luck deciding.

 

[350xfire]

My newest design will use the Taskled latching hall effect and I will mount the magnets in a small hole in the cap. The hole will be drilled from the inside of the cap and will not go through. Just swipe and on, swipe and off.

 

[Codiak]

Thanks for clarifying my screwup klem

My previous lights are all just on off with piezos
I've been working with 3 prolongated piezo switchs of late and am spoiled.


If the is enough interest in a group buy, the prolongated switches can be had for around 22$ US not including shipping.
If I recall correctly we only have to buy 10

 

[Klem]

Thanks for clarifying my screwup klem

My previous lights are all just on off with piezos
I've been working with 3 prolongated piezo switchs of late and am spoiled.


If the is enough interest in a group buy, the prolongated switches can be had for around 22$ US not including shipping.
If I recall correctly we only have to buy 10

Yes, I remember we PM'd about this. I'd be happy to put an order in plus postage for a few, if you're happy to chuck mine in the mail.

I only managed to get 2 direct from Baran Tehcnologies at the princely sum of $70 each because of the FEDEX they insisted on plus the $30 my bank insisted on. Certainly not EBay and Paypal for sure!

Using drivers' with both 'clicks' and 'presses' is asking for trouble with a Hall. Even with a prolonged piezo I find it's quicker and less mistake-prone if I change programming using a simple surface mount momentary before sealing it up for the dive.

 

[beekeeper5]

Thanks everybody for the great information! The momentary switch I was thinking about is actually a momentary toggle switch. The switch with a little joystick sticking out something like this but cheaper http://www.nextag.com/74124-Momentary-On-Toggle-1239984188/prices-html . Then I would put a boot on it to make it waterproof.

As for the piezo, I'd be interested in it providing that you can show me how to wire it up and how complex it is. :)

I'm starting to lean away from the hall switch when the driver is a multi-mode. I haven't decided yet what I'll use. What's the next best thing besides a piezo?

 

[Packhorse]

The piezo is the best option in my opinion.

And as I've said before the magnet adds to my task loading... I never want to second guess myself or equipment while narced

How so?

Sure if you have a magnet on a bit of string that you have to find and swipe across the sensor/reed but thats poor design.
A properly set up push button magnet is very reliable and simple to use.
Look at the Intova lights with the button on the end.
There is a connection for as long as the button is pushed down so quick pulses or long ones are easy.

 

[Klem]

Yes, that should work (momentary joystick) and is a cheap solution, bearing in mind you now have something sticking up which you need to protect from getting cut or bashed.

As for Hall and a multi-mode driver...It's not so much the multi mode but the operation of those modes with 'clicks' and 'presses'. If it were just 'clicks' then you could tap away with your Hall or have a magnet mounted somehow on the torch body.

How complex is a momentary piezo?...Almost the same as the joystick switch you are planning on buying. You drill a hole, glue the piezo in place, and solder the two wires coming out the bottom of it to the two pads on your driver marked 'switch'...simple!
http://www.baran-at.com/s5.html

It's actually simpler than your joystick because you don't have to put a rubber boot on it...it's already waterproof.

What's the next best thing besides a prolonged piezo?...well, that depends. A Hall reduces the chance of flooding by the switch to zero, but is a pain to operate underwater (and the effort required for some divers exceeds what they will tolerate). Your momentary toggle/joystick will work, but is high profile and therefore a flood and damage risk from being bashed, pierced, perished. You would need to protect it by a collar or similar. Another option is to use a magnetic reed switch with a magnet instead of a Hall. Similar concept and pricing to the Hall. That's pretty much it, unless someone can contribute something I've missed.

 

[Klem]

How so?

Sure if you have a magnet on a bit of string that you have to find and swipe across the sensor/reed but thats poor design.
A properly set up push button magnet is very reliable and simple to use.
Look at the Intova lights with the button on the end.
There is a connection for as long as the button is pushed down so quick pulses or long ones are easy.

Pack,

Agreed, and a perfect solution for diving...Possible but difficult...After playing around with George's 'click' and 'press' drivers with a Hall I can say that you would need to carefully manage torch construction so that the Hall is positioned perfectly vis-a-vis the position of the magnet. The mechanical range of the moving magnet would be measured in millimetres and that range needs to be exactly crossing the threshold of the Hall.

Given in any torch design the Hall's position inside the torch would be pretty much preferred and fixed, and the magnet switch you would also want in a certain location on the body then that leaves magnet strength and (if possible) the Hall's attitude to secure the threshold at exactly the range of the magnet's movement when pressed. The longer you make the travel of the magnet the harder it is to do <0.3sec 'clicks' and the clumsier the switch starts to look (be it up and down, or forward and back).

Difficult, but I'm thinking not impossible.

Also, if the magnet's strength is compromised in any way, bashed around or other magnets, then that carefully worked out threshold could shift to either side of the range of movement of the magnet.

 

[beekeeper5]

How complex is a momentary piezo?...Almost the same as the joystick switch you are planning on buying. You drill a hole, glue the piezo in place, and solder the two wires coming out the bottom of it to the two pads on your driver marked 'switch'...simple!
http://www.baran-at.com/s5.html

That's it?!? I thought I need a relay/mosfet with the piezo. I'm leaning towards piezo but I'm afraid $70 is a bit too much. I'd pay $22 + shipping (poking at Codiak :) )

 

[Klem]

That's it?!? I thought I need a relay/mosfet with the piezo. I'm leaning towards piezo but I'm afraid $70 is a bit too much. I'd pay $22 + shipping (poking at Codiak :) )

Correct, the tiny current needed across your drivers switch terminals will be well within a piezo's rating.

 

[beekeeper5]

Uncle Kelm, did you get the SMF6?

 

[Klem]

Yes, it's their smallest diameter at 16mm.

Also fits perfectly into a Maglite switch hole.

 

[DIWdiver]

My two cents:

The old Darrel Allan and some Princeton Tec lights used a slide switch that was built into the housing. The slider contained a magnet and there was a reed switch inside. It seemed to me a pretty decent way to do it.

I never owned a Darrel Allen (which I'm hoping to correct someday), but the Princeton Tec collected iron particles on the magnet, which made the action a bit sticky. If you use magnets on dive gear, make sure you can clean it out after diving a few wrecks.

Hall effect sensors are cool, but the biggest problem with them is that they need power. And most of the good ones need power in a narrow voltage window. George at TaskLed has built a board that takes care of the electronics for you, but you still have to figure out how to mount the board and the magnet so the whole thing works. If you're into designing mechanical stuff, it's a great choice. The light which is now my main light uses three Hall sensors and a ring with two magnets in it to operate a 5-mode driver (all custom built).

I have to say, though, that I love the piezos. Not only that it can be completely sealed with no moving parts, but the idea that the deflection of that solid metal cover is enough to activate electronics without any fancy or difficult assemblies never ceases to amaze me. Schurter seems to be the only real player in the US, but I think Apem has some available in Europe. If you are at all into electronics, it's actually pretty easy to build your own extended operation piezo switch. It can be done with only two parts - the piezo element and one chip. Both parts are cheap, easy to find, and easy to use. Here's how to do it: http://www.candlepowerforums.com/vb/showthread.php?296774-DIY-piezo-switch&highlight=diy+piezo

D