Switches - lets talk - for altimeters & electrocnics

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Cris,
One of the things the BoD liked about the WiFi switch was that it was a separate switch, so when it’s output is off, the leads on the avionic FETs (or whatever power switching device you use) are not connected and thus insensitive to a transient. Do the Quantum and TRS also isolate the output devices until the avionics sections are commanded ON?
The Quantum is dual-switched, it's shut off on both sides of the deployment load until it's turned on by arming it AND by a deployment/ignition event. There's no "common" to one side of the battery like there is with virtually all other altimeters. The TRS is more conventional... the "-" side is common, however nothing can happen until it's armed with the LCD receiver, and like other Eggtimer altimeters the deployments transistors are isolated from the altimeter side via optoisolators. It's highly immune to any outside interference.
 
Few of the reasons I really like the pull pin switches 1. With pin and flag hanging out really hard to forget to arm on pad 2. Easy to disarm when recovering rocket 3. Pin small enough to insert through static hole even on 38mm rocket 4. Easy to use them in tandem with multiple altimeters 5. Very reliable I have heard of failures with rotary switches and I think perfect flight even recommends not using those. 6. And I think looks cool with all the remove before flight flags hanging out ( but I am a retired A&P mechanic so may be biased on that one) Lol
 
Cris,
One of the things the BoD liked about the WiFi switch was that it was a separate switch, so when it’s output is off, the leads on the avionic FETs (or whatever power switching device you use) are not connected and thus insensitive to a transient. Do the Quantum and TRS also isolate the output devices until the avionics sections are commanded ON?
The Quantum's outputs are totally isolated from the battery, there are switches between both ends of the igniter and the deployment power. Both switches need to be turned on for an igniter to fire, that can't happen until it's armed on the ground first AND you reach the trigger thresholds in flight. The TRS is more conventional, the "-" side of the deployment battery is common to the igniters. For a L3 cert use, a TRS would require a separate switch on the deployment power. When I did my L3, my TAP still required the deployment power on my two Quantums to be mechanically switched off; it's easy to do and I certainly wasn't going to try to debate the point with him.
 
Same switch, but with integrated pin guide. I also have the double switch version in the store. Both come with mounting hardware and pull-pin. They have been quite popular.

Single: https://www.labratrocketry.com/product-page/pull-pin-switch-kit
Double: https://www.labratrocketry.com/product-page/double-pull-pin-switch-kit

This is a professional version of what I've made by hand, although I use nylon screws instead of pull pins and rig them so that putting the screw in turns on the electronics. Then I put a "remove to make safe" label on the outside in case the rocket wanders off during a flight and a civilian finds it beeping somewhere.

Snap switches (e.g., microswitches) are typically extremely reliable; if you're worried about vibration or g-forces you can mount a pair of them in different axes and wire them in parallel to reduce the chance of accidental "bounces" during ascent.
 
Absolutely. The only exception is for LEVEL 3 CERTIFICATIONS, they want a physical switch between the battery and the electronics. Once you get your L3, you don't need the switch. Ditto for any switches that your Tripoli L3 TAP may require... I was explicitly told by my Tripoli TAP that once I got the cert, I could remove them. Note that these rules apply to ALL electronic switches, or any other altimeter that might incorporate an electronic switch... that includes magnetic switches, too.
 
Absolutely. The only exception is for LEVEL 3 CERTIFICATIONS, they want a physical switch between the battery and the electronics. Once you get your L3, you don't need the switch. Ditto for any switches that your Tripoli L3 TAP may require... I was explicitly told by my Tripoli TAP that once I got the cert, I could remove them. Note that these rules apply to ALL electronic switches, or any other altimeter that might incorporate an electronic switch... that includes magnetic switches, too.
Cool. I was planning on launching this weekend with a Quantum @ Bong but it's an Nar launch. Tripoli is next weekend I believe. So you need a physical switch on a Quantum ONLY for an L3 cert flight. All other flights you can arm/disarm over wifi. Correct?
 
After using voltage switches or twist and tape exclusively for 10 years. I am switching (no pun intended) to Lab Rat Rocketry's switches. They are simple to use and install and I like the idea that I can better switch them off by inserting the "key".
 
After using voltage switches or twist and tape exclusively for 10 years. I am switching (no pun intended) to Lab Rat Rocketry's switches. They are simple to use and install and I like the idea that I can better switch them off by inserting the "key".

Awesome! Glad you are happy with them, Chuck.
 
Cool. I was planning on launching this weekend with a Quantum @ Bong but it's an Nar launch. Tripoli is next weekend I believe. So you need a physical switch on a Quantum ONLY for an L3 cert flight. All other flights you can arm/disarm over wifi. Correct?
Yup.
 
My pull pin switch kits are now available with "Remove Before Flight" flag upgrades.

 
Just used one of Lab Rat's switches yesterday for my L2 flight on a K456. Was on an Eggtimer Quark for redundancy. All charges fired when they were supposed to. Had a Quantum for primary so no switch necessary. Therefore Lab Rat switch gets thumbs up.
 
I just bought my own flags! Will you sell just the pins?

The last thing I want to do is punish an early adopter. As soon as I have more stock of flags I will put the pins in the store with 3 options: Standard Cap, Flag Cap (no flag) and Flag Cap (with flag).

Just used one of Lab Rat's switches yesterday for my L2 flight on a K456. Was on an Eggtimer Quark for redundancy. All charges fired when they were supposed to. Had a Quantum for primary so no switch necessary. Therefore Lab Rat switch gets thumbs up.

Congrats on the L2, and thanks for the good word.
 

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Well...Three thumbs up for Lab Rat then. They cost less, come with all necessary hardware and I don't need an extra tool to arm/disarm;).
 
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Two thumbs up for the Fingertech Screw switches.
Hey, those things look very durable and are just the right size as well. I ordered up a couple and am anxious to see how they work.
 
I use the Fingertech 40A screw switches as well. Didn't know they existed before working with the ARLISS 100k team, but that's all I use on mission critical flights and also recommend them to those designing their L3 certification airframes. A few dollars extra for piece of mind seems like a bargain to me.
https://www.robotshop.com/en/fingertech-40a-mini-power-switch.html have the best price I've found for quantity purchases.
 
I use the Fingertech 40A screw switches as well. Didn't know they existed before working with the ARLISS 100k team, but that's all I use on mission critical flights and also recommend them to those designing their L3 certification airframes. A few dollars extra for piece of mind seems like a bargain to me.
https://www.robotshop.com/en/fingertech-40a-mini-power-switch.html have the best price I've found for quantity purchases.
I'll admit they are nice, excellent actually. But I just can't see paying over $7 for maybe 50 cents worth of "stuff"..Maybe if I decide to L3 someday..
 
I've been using screw switches exclusively. Low/zero profile, reliable, and not too hard to set up with some forethought.

I really like the Eggtimer Quantum / WiFi switch, WAY easier than fiddling with a screw switch (or being anywhere by the rocket when you arm), but as others noted it's a battery hog and it precludes "pre-packing" the rocket before heading out to the field.

As a compromise, I've taken to mounting a screw switch even with the Quantum so I can pre-pack, and, if it's fiddly, I'll power up on the bench, verify continuity, and just head out to the pad. Our field doesn't have long waits, so the extra battery draw is minimal.
 
Does that apply to the TRS as well? Can I plug the battery to my TRS without a switch at the flight line, leaving it unarmed until the rocket is on the pad, then arm it with the LCD receiver?

Ahhhhhhh, That's what I've been doing with a minimum diameter project. Since the TRS doesn't make much of a racket in standby mode, nobody is going to know. I did put a Featherweight screw switch on the pyro circuit but I have
flown an even smaller project without any switches whatsoever. Not enough room. I thoroughly bench tested, felt comfortable and it just works. Before every flight with the "switchless" setup, I test with bare ematches the night before to make sure the risk of charges going off on the particular TRS is nil when plugging in the battery. Once satisfied, I will setup for live charges and use common sense when plugging in the battery.

For cert projects, to keep TAPS and L3CC's from soiling their pants, use a project that one can put a switch on the battery or you'll likely not be approved for flight. Even though TRA says it's kosher, the individual TAPs are allowed to make judgement calls so to avoid issues use a large enough project you can put/fit switches in.
Switching a TRS technically not necessary but in a complex project, I'd do it so I could be safely at a distance to ultimately "arm" it. I don't foresee going to that level though (ie. multistage project)
Or............... As I mentioned above, put a screw switch on the TRS pyro circuit in case somebody were to question me about direct powering the TRS. On that project, I use one 1300mah 2s battery in parallel to power the unit and for pyro
purposes. More than enough capacity to fly.
 
Ordered from Lab Rat to be used on my L2. Received the order quickly and well packaged. I like what I see, and if it performs as good as it looks, I will be ordering more in the future.
 
This is a professional version of what I've made by hand, although I use nylon screws instead of pull pins and rig them so that putting the screw in turns on the electronics. Then I put a "remove to make safe" label on the outside in case the rocket wanders off during a flight and a civilian finds it beeping somewhere.

Sounds like a great idea where that feature is needed. I hope you don't mind if I steal this idea for my sustainer ignition circuit on the Nike Apache. ;)
 
I normally just quickly pull the pin, insert the sled into the bay, and reinsert the pin. No charges usually at this point so quite safe.

I have been known to use a wooden skewer just sitting flush with the sled and pull it out later also. This trick works good while you are working in the open bay. Makes it easy to turn over without pins falling out etc.
 
I normally just quickly pull the pin, insert the sled into the bay, and reinsert the pin. No charges usually at this point so quite safe.

There may be charges connected, depending on the ebay design and how it is affixed in the rocket.

I don't like the idea of hurriedly trying to assemble an ebay while an altimeter is going through start-up. I like this switch but would use it with caution only in certain designs.
 
This is a professional version of what I've made by hand, although I use nylon screws instead of pull pins and rig them so that putting the screw in turns on the electronics. Then I put a "remove to make safe" label on the outside in case the rocket wanders off during a flight and a civilian finds it beeping somewhere.

Snap switches (e.g., microswitches) are typically extremely reliable; if you're worried about vibration or g-forces you can mount a pair of them in different axes and wire them in parallel to reduce the chance of accidental "bounces" during ascent.

Ted, I am with you. I use 6-32 arming screws, turn them in a bit to hold in place when prepping and then screw them in the rest of the way to physically hold a switch in a closed position and arm the electronics. I agree about microswitches and reliability, but I just like any switch to be physically held in the "on" position for arming.
 
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