ISO of plot of Schurter (110/220) rotary switch failing.

Handeman said:

You might want to consider this one. It's basically the same switch without the roller on the end of the arm. Since the arm is pretty much free/loose when the pin is pulled, having less weight on the end that can impart movement is a good thing in my opinion. A strong jolt is less likely to affect the light bare arm then the one with the relatively heavy roller.

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Only the SS-5F is rated to carry the DC current that I would prefer. Also, I would specify the 1.47N operating force model. It’s capable of withstanding 100G mechanical shock. I don’t see that it even comes with an arm. If not the 1.47N model, then at least the 0.49N one.


Steve Shannon

mpitfield said:

So why are people still considering using them?

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Old habits die hard, I guess. The Schurter switch was all the rage a few years ago, and I bought a bunch of them. Various 3D printed sleds use the rotary switch layout. The switch is not tiny, easy to solder, clamps securely with a nut to a sled, has a nice slot for a screwdriver, and makes a satisfying "click" when you turn it on.

I never had a problem. I never heard of a failure until somebody mentioned the Perfectflite warning a year or so ago.

I used the Schurter switches, twist and tape, and the Missileworks screw switch.

I stopped using the Schurter entirely a couple years ago. On a cold day I was helping a friend prep his L3 rocket. Turned the switch while holding it in my hand, and it literally came apart in my hand.

Now, it is twist and tape or the Missileworks.

The Fingertech switch CJ mentions looks good. Not sure how it is superior though to the Missileworks or Featherweight screw PCB switches?


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qquake2k said:

What do you guys think about this kind of switch? I know it's big, but it's going in a 7.5" tube. It's rated at 50,000 electrical cycles and I like the indicator light.

https://www.adafruit.com/product/482

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That does look like a good switch for a larger rocket. Especially one using LiPos which get charge before every flight. I know the LED doesn't draw much, but after the initial indication of power on, it's just a wasted battery draw throughout the flight. Shouldn't be a problem with 2s LiPos, but if you're using 9V, it could become an issue.

qquake2k said:

What do you guys think about this kind of switch? I know it's big, but it's going in a 7.5" tube. It's rated at 50,000 electrical cycles and I like the indicator light.

https://www.adafruit.com/product/482

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Look at the data sheet. What’s the mechanical shock rating?


Steve Shannon

Being hands on and real world has always been better to me than conjecture, so I wired up a Schutner to a 2S LiPo and a small LED light and turned it off and on for 400 cycles. It worked each and every time. I know this only proves that this one particular switch is fine, perhaps it will fail on the 401st try.

I had a switch with built in LED. Failed to arm with a new 9V battery. I had to borrow an ebay to fly. After I got home, it took some dissecting to discover the problem. I tried 2 different batteries and even swapped the altimeter in the field, but didn't have anything to lower the voltage required to power up without throwing the low voltage alarm.

Here's one of the Fingertech screw switches from the posts above after some unpleasantness.



I think it still works!

cavecentral said:

I had a switch with built in LED. Failed to arm with a new 9V battery. I had to borrow an ebay to fly. After I got home, it took some dissecting to discover the problem. I tried 2 different batteries and even swapped the altimeter in the field, but didn't have anything to lower the voltage required to power up without throwing the low voltage alarm.

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I'm not following you. What exactly was the problem? I don't see how an LED could draw enough to keep the altimeter from arming. Which altimeter was it?

Is the warning about the switches on Perfectflite's website? What exactly is the warning?

Zeus-cat said:

Is the warning about the switches on Perfectflite's website? What exactly is the warning?

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Slip of paper in the bag with the altimeter.

I briefly used Schurter switches but stopped doing new builds with them after I had one come apart on a hard landing. I did a surgical post-mortem and concluded that the mechanical design was pretty dismal for rocket applications. After that I got a supply of reasonably decent rotary key-style mini switches that someone linked to here. They've been OK but a bit bulky...having just run out of those I'm going to start using the FingerTech units, which look like a great design for our purposes.

caveduck said:

which look like a great design for our purposes.

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If they just had a mounting option that aligned axially with the screw.

Flat down on a bulkhead is fine with me. You can bolt them on and they are not coming loose short of a 300G crash scenario. For smaller diameter birds I'll just bolt them to a small piece of aluminum 90deg angle stock, which will reduce the footprint on the bulkhead by 60-70%.

caveduck said:

Flat down on a bulkhead is fine with me. You can bolt them on and they are not coming loose short of a 300G crash scenario. For smaller diameter birds I'll just bolt them to a small piece of aluminum 90deg angle stock, which will reduce the footprint on the bulkhead by 60-70%.

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Certainly, just more stuff in my avbays.

Back to the OP. I don't understand the title of this thread. What is an "ISO of plot?" Plot of what? Is this new lingo the kids are using these days?

Buckeye said:

Back to the OP. I don't understand the title of this thread. What is an "ISO of plot?" Plot of what? Is this new lingo the kids are using these days?

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Not sure which part you're not getting so I'll hit it all:

In Search Of a plot. A graph showing the voltage fluctuating and/or dropping out.

Exactimator said:

Not sure which part you're not getting so I'll hit it all:

In Search Of a plot. A graph showing the voltage fluctuating and/or dropping out.

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I figured as much.

47 posts later and no plot produced makes me wonder what the OP hopes to see in such a plot. If the switch completely failed, then the altimeter turns off and there may be no data recorded, anyway. If the switch bobbled, then you might see fluctuating voltage rather than a rock solid straight line in the data. Who can say with certainty? Voltage drops can occur for a variety of reasons, including firing ejection charges. Seems like a bench test of the switch alone would be better than relying on flight data to diagnose the switch.

I am guessing that this post is related to this one: https://www.rocketryforum.com/showt...Logger-CF-log-voltage-to-the-100ths-of-a-volt

Johnly said:

I've been using FingerTech Robotics switches on my new builds.
https://www.fingertechrobotics.com/proddetail.php?prod=ft-mini-switch
When you have $1000 invested in an airframe and electronics it seems a wise choice to use "bulletproof" switches for the electronics.

John

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I am pretty new to all of this, but not new to electro-mechanical creations. I bought a number of the Schurters, and some of the fingertech switches, and studied them for a bit. I like the fingertech switches much better, and sent the Schurters along to a good home.

Exactimator said:

Not sure which part you're not getting so I'll hit it all:

In Search Of a plot. A graph showing the voltage fluctuating and/or dropping out.

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ISO also means "International Standards Organization," which could be confusing to be people who only know that meaning of the acronym.

TLAs are so context sensitive.

Bat-mite said:

ISO also means "International Standards Organization," which could be confusing to be people who only know that meaning of the acronym.

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That's what I thought the OP was asking. Which made no sense at all to me.

Zeus-cat said:

That's what I thought the OP was asking. Which made no sense at all to me.

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Yeah, it probably puts me in the ignorant bracket but it seems like a lot of people are making up acronyms without any introduction.

qquake2k said:

TRF is acronym heavy. Gave me fits when I first joined.

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TRF is AH- GMF WIFJ

Much better.

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You have no idea what acronym-heavy is like until you work for Agilent.

OverTheTop said:

You have no idea what acronym-heavy is like until you work for Agilent.

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Every company or industry has its own jargon, acronyms and odd language, but the military takes first prize in those categories.

Zeus-cat said:

Every company or industry has its own jargon, acronyms and odd language, but the military takes first prize in those categories.

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Yup. DoD uses acronyms of cover names, which in themselves make no sense.

Back when our company was phasing out old Gateway 2000 computers, I raided all of the computer case shells and removed the SPST switches from them. These are simple 2-position switches with a cylindrical key. I have been using them for my electronics now for 17-years. Here is a source similar to what I am using:

https://www.jameco.com/z/S126-2-Rou...2WPxoSvOCidaGwi6K2rBGgVBSEYx2_PBoCc-sQAvD_BwE