Switch Testing

[JohnCoker]

After a long hiatus, I have posted a new video, this time on testing switches for electronics.

 

[cerving]

Interesting, but no pull-pin snap switches?

 

[Worsaer]

Nicely done John. Thank you for taking the time and effort to do these tests. I agree some results are surprising, particularly in view of the commonly held views in the Rocket community.

 

[Jeremy Sim]

Another great video John!!!

 

[Steve Shannon]

Excellent, John!

 

[cwbullet]

Interesting the the one used in Combat Robotics did so poor.

 

[JohnCoker]

Interesting the the one used in Combat Robotics did so poor.

I'm not really sure that it did that poorly, but perhaps what they care about is not the same as what we care about.

 

[JohnCoker]

Interesting, but no pull-pin snap switches?

Maybe a second round is in order later on. I was limited to 7 (and next time I'll limit it to 6 so I can keep a constant ground too).

 

[cautery]

Maybe a second round is in order later on. I was limited to 7 (and next time I'll limit it to 6 so I can keep a constant ground too).

Let me know if you need help from the incurably OCD...

 

[jahall4]

After a long hiatus, I have posted a new video, this time on testing switches for electronics.

Could "Bob" have gotten the FingerTech switch to hot while soldering?

From a FB post of mine last year... "The FingerTech has a failure mode… you have to keep the solder temperature well below the rating. I have had one become permanently “open” after the solder, it worked before and then it didn’t, simply would not close the circuit and turn on the altimeter..."

 

[cwbullet]

The Fingertech and Voltage switches have worked well for me. I also have used the PCB switches and Pull pins. I will probably use them in the future and change based on the needs of the build.

 

[dvdsnyd]

Would be really curious to see how the FW magnetic switch and Eggtimer Wifi switches fair.
As always, great video and appreciate the data!

 

[JohnCoker]

Could "Bob" have gotten the FingerTech switch to hot while soldering?

From a FB post of mine last year... "The FingerTech has a failure mode… you have to keep the solder temperature well below the rating. I have had one become permanently “open” after the solder, it worked before and then it didn’t, simply would not close the circuit and turn on the altimeter..."

Yep, I ruined a switch that way in the past as well. The terminals are large so they take a lot of heat to get the solder to flow, but they're also in direct contact with the Nylon switch body. The switch in this test still turned off and on, but it was very noisy turning on.

If there was a lug that fit these terminals properly, that might be a better option. Anyway, for me these are a bit too finicky and I'll stay away in future.

 

[JohnCoker]

Would be really curious to see how the FW magnetic switch and Eggtimer Wifi switches fair.
As always, great video and appreciate the data!

I'd assume solid-state switches would be both instant and immune to mechanical stresses, but it's worth testing.

 

[kjhambrick]

Good stuff !

I too would like to see how the Mag Switches fare.

Thanks John.

-- kjh

 

[cwbullet]

Yep, I ruined a switch that way in the past as well. The terminals are large so they take a lot of heat to get the solder to flow, but they're also in direct contact with the Nylon switch body. The switch in this test still turned off and on, but it was very noisy turning on.

If there was a lug that fit these terminals properly, that might be a better option. Anyway, for me these are a bit too finicky and I'll stay away in future.

I did also. I chose to crimp and use a spade connector on the switch the last several times.

 

[cautery]

Yep, I ruined a switch that way in the past as well. The terminals are large so they take a lot of heat to get the solder to flow, but they're also in direct contact with the Nylon switch body. The switch in this test still turned off and on, but it was very noisy turning on.

If there was a lug that fit these terminals properly, that might be a better option. Anyway, for me these are a bit too finicky and I'll stay away in future.

I did also. I chose to crimp and use a spade connector on the switch the last several times.

I have a stack of these switches here. How are y'all soldering that the chassis is melting? Things I would try (and will now if I get a moment to breath):

1) Use 63/37 tin/lead eutectic solder or other low melt/freeze solder (63/37 = 183 C) (Lead free solder melts/freezes at a significantly higher temp reducing your potential delta between iron temp and solder flow temp. No silver bearing.)
2) Choose a NEW tip that gives max surface contact to exposed pin surfaces away from housing.
3) Clean the contacts very, very well.
4) Use supplemental liquid flux.
5) Turn the heat UP!!! Put the heat to the pin. USE A GOOD soldering station. There is a magic temp at which the dwell time is minimized against the total thermal gain in the pin. AKA: Get it hot to take solder FAST BEFORE heat soaks plastic and turns it to sludge.
6) Make SURE tip is freshly cleaned/tinned JUST before making bond.
7) "I" like to keep my tip a little "wet" so that when I touch it to the junction, the molten solder acts a little like a "surfactant" for breaking solder tension to pin and encouraging rapid heat flow right where I want it.
8) Practice...

This has worked well for me in the past when soldering tiny sensitive things to other tiny sensitive things... without killing either.
I could solder a pigtail on one and test it at audio frequencies on my radio set. You can HEAR noise above about 100Hz, so 500 Hz over a good set of cans is a no sweat deal. If it is quiet to a DXer at audio, I could also send it to you for a followup.

I am also VERY interested in the testing results from the microswitch-based switch with the pull pins.

 

[jahall4]

Would be really curious to see how the FW magnetic switch and Eggtimer Wifi switches fair.
As always, great video and appreciate the data!

I can tell you there is a short delay when they are switched on because I use them for ground testing.

 

[jahall4]

I have a stack of these switches here. How are y'all soldering that the chassis is melting?

Its not that it "melt(ed)" it just didn't work after it was soldered. Turning the iron temp down, using a larger tip seemed to help.

 

[jahall4]

Yep, I ruined a switch that way in the past as well. The terminals are large so they take a lot of heat to get the solder to flow, but they're also in direct contact with the Nylon switch body. The switch in this test still turned off and on, but it was very noisy turning on.

If there was a lug that fit these terminals properly, that might be a better option. Anyway, for me these are a bit too finicky and I'll stay away in future.

Twist-n-tape is looking better everyday, just concerned about using on a Mach rocket. ;-)

 

[Titan II]

Twist-n-tape is looking better everyday, just concerned about using on a Mach rocket. ;-)

Not a problem.

 

[Adrian A]

After a long hiatus, I have posted a new video, this time on testing switches for electronics.

Thanks for the testing.

Just to be clear, the vibration sensitivity you noted on the Featherweight screw switch was when it was in the open position, correct? This would be representative of something like transporting a rocket on the ground. I recommend that the screw be removed from the switch for transport if the switch is used in a safety-critical application, which I believe would eliminate any possibility of vibration sensitivity. When the screw switch was screwed down to close it as it would be for flight, did you note any vibration sensitivity?

 

[Titan II]

I use a lot of this type switch and never remove the screw. Any concern it can close during transportation can be easily mitigated. It is discussed in this thread.

Featherweight Screw Switch - Safety FYI/Alert

All, I wanted to share a safety concern that I have encountered. I have a rocket that utilizes these PCB mount screw switches. Twice now, I have had the rocket arm itself during transit. I keep my Av Bays prepared and in the house until it's time to transport as I don't want to expose my...

www.rocketryforum.com

BTW...thanks for your work John.

 

[manixFan]

It might be useful to use the live data function of an accelerometer to measure force when you smack the table with the board, since that's how we measure the kinds of 'hits' our switches see. Plus it would give you better test-to-test data if you have some numbers behind the force. The same with the screw switch – using a torque screwdriver to measure the amount of force used to tighten the screw. I have a feeling that 'tight enough' varies considerably among users. Great info, looking forward to more.


Tony

 

[cwbullet]

I use a lot of this type switch and never remove the screw. Any concern it can close during transportation can be easily mitigated. It is discussed in this thread.

Featherweight Screw Switch - Safety FYI/Alert

All, I wanted to share a safety concern that I have encountered. I have a rocket that utilizes these PCB mount screw switches. Twice now, I have had the rocket arm itself during transit. I keep my Av Bays prepared and in the house until it's time to transport as I don't want to expose my...

www.rocketryforum.com

BTW...thanks for your work John.

I do think it is a bad idea in general to travel with charges loaded in a vehicle with any switch that might be affected by vibration.

I think featherweight recently changed their switches.

 

[JohnCoker]

Thanks for the testing.

Just to be clear, the vibration sensitivity you noted on the Featherweight screw switch was when it was in the open position, correct?

Both actually. Here's my "0" test (all switches off) at 500Hz. Note that purple is #5 (the Featherweight screw switch).



Here's my "5" test (only Featherweight on) at 500Hz. Note that blue is the Shurter.



If anyone is interested, I can send the data files. They're saved in TDMS format, which is consumable by many programs. (I used "DAQami", which comes from the same company that made the sampler.

 

[Handeman]

I do think it is a bad idea in general to travel with charges loaded in a vehicle with any switch that might be affected by vibration.

I think featherweight recently changed their switches.

I tend to agree, except I travel with loaded charges in rockets in the bed of my pick up. They are all screw switches, but we'll see if that ever causes an issue. I suspect not, but who knows../

 

[JohnCoker]

It might be useful to use the live data function of an accelerometer to measure force when you smack the table with the board.

Agreed. I had plans to do this, but I didn't figure out how to and eventually I decided to publish what I had.

If someone wants to make me a daughter board that measures acceleration and provides a readout that doesn't require another computer, I'll get numbers for what I did and what I do in future.

I started this in 2017, but got stalled by various issues along the way. Late last year I bought the shaker and amp, but I decided not to wait for a way to measure acceleration of the "jolt" tests.

 

[pbahorich]

I appreciate the testing. I'm not sure why time to turn on and noise while turning on are important in our application. We turn electronics or initiator circuits on, once, and time on should be irrelevant unless it is in minutes. Could you elaborate on why you feel they are important?
Since the physics of the Fingertech is similar to the Featherweight switch, if the behavior in turn on and noise is significantly different, I'd suspect the test setup.
I would think that for our application, vibration and shock should be paramount. If a switch starts generating noise or bounce when it is supposed to be connected, that is a show stopper. That is why I think the Schurter and Featherweight belong at the bottom of the list.
Toggle switches are well established in aerospace applications, so no surprise there.
Slide switches typically don't have good endurance and are thus not typically used in aerospace applications.

 

[rocket_troy]

I appreciate the testing. I'm not sure why time to turn on and noise while turning on are important in our application. We turn electronics or initiator circuits on, once, and time on should be irrelevant unless it is in minutes. Could you elaborate on why you feel they are important?

It shouldn't be important in an ideal world for users. Commercial flight electronics should have a suitable rail-rail smoothing cap to deal with such eventualities, although this testing provides those (electronics) designers some data to design for. Remember however, there are violent and dangerous pyros attached to flight electronics so you also want to minimize the chance of the flight electronics experiencing a bit of a confused meltdown on powerup.

TP