Discussion in 'Rocketry Electronics and Software' started by cwbullet, May 1, 2019.
I concur. This is a very unique solution.
I am very impressed with the variation of switches.
I haven't checked them before but I will now. I did take that switch apart and I don't see any cracks. There is a crease in the foil that I will fix because it is a weak point. I usually put the foil on both sides of the switch block for redundancy.
Thought about using something like brass shim for the contact? Might be more robust.
G'day Mate. I hadn't thought about trying that. I have the shim stock on hand it just seemed so easy to use the single sided pcb material and the thin copper foil. I got the foil for another project from a luthier supply store.
Two more fantastic options!
This is for general sport flying. For high performance rockets I use screw switches. If you don't get a completely normal startup sequence don't fly the rocket!
That presumes the ejection charges don’t blow as a result of an abnormal startup sequence. I think most altimeters now have de-bounce protection, but I’ve had AltAccs blow charges as a result of transients on startup.
Is that the French version of Bounce Protection?
That would probably be du-bounce.
You’re right. I should have said bounce protection or a debounce circuit. Mea culpa, mea culpa, mea maxima culpa.
I like MissleWorks screw switches that I arm through the airframe, the static port holes providing my access to the arming screws, and no switch band. Photos are of a 3" AV Bay. The sled goes from rocket to rocket while each rocket gets its own AV Bay...
+3 on the Featherweight magnetic switches. I have them in three of my rockets and am considering buying more.
Anyone know where I bought these from? Would like to buy a few more, and I simply cannot remember where I got them from. Searched several of my go-to vendors and do not see this kind with the terminal block at the end of the switch.
Dog House Rocketry?
Its only downhill from here.
No this is not it, it does not have the terminal block on the end.
Designed and made one of these from scratch. uses a standard microswitch and has a lid to keep things neat. Used with pull-pin and "remove before flight" flag. I plan to install it in the av bay with the lever down.
Pin in, "off" position.
Pin out, "on" position.
I was using a Radio Shack headphone jack the same way, and while the can take the G forces in the correct orientation, they are fragile mechanically. I broke mine by bumping the pin against the launch rail. Fortunately, it broke in the "on" position!
the article, while informative, does not apply to the microcontroller chips used in the alitmeters. Early microcontrollers did not have any built-in protection that basically delayed startup of the micro until power was thought to be stable. They required a capacitor, resistor, and typically a diode on the microcontroller's reset line. When power bounced off the diode would drain energy from the capacitor and when power bounced on, the capacitor would charge through the resister. If the reset pin managed to reach a threshold voltage, the microcontroller would start at a boot location and run code.
I know a lot of people use the Shurter switch - it is not a power switch. It is designed to route wires when power is not applied for voltage selection in some 110v/220v powered device. It is not designed with any concern for switch bounce or even long term usage as a switch (it was meant to be used a few times switching to whatever line voltage you have in your house or work). The slide versions of a voltage selector switch are better than the rotary one at least for the switch bounce aspect. I can't comment on switch longevity for those.
At least the microcontrollers I design with have some digital counter available that holds off the micro from starting up too soon.
If you are using a commercial switch that is designed as a power switch, then whatever you do should be just fine.
If you can get some images of the markings on the case, we might be able to find the part.
I made a round tube with 2 4-40 brass nuts printed inside by departed by 2mm of plastic filament. I then solder wires to the nuts. A screw completes the circuit.
#6 brass screw switch integrated into my altimiter sled.
It's an excuse to play with my torch, don't forget your flux!
Be careful the flux doesn't wick down the multi-strand wire and cause corrosion inside the insulation .
I'll keep that in mind. The flux I used is water soluble and I washed everything before putting on the heat shrink.
Are those McMaster Carr
Brass Flanged Knurled-Head Thumb Nut? https://www.mcmaster.com/92741a110
Close, I got them from lowes actually:
No physical switches. Plug the Quantum in at the prep table. And magnetic switch on the power perch.
Separate names with a comma.