First timer needs help

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geof

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I'm doing my first DD, which is also first time with electronics. Generally, I'm doing ok but I feel confused about the switch. Schematically, the contents of my av bay look like the sketch (ignoring the drogue). I want a switch on the side of the rocket, accessible from the outside, to turn the altimeter (RRC2) on/off.

The guy who sold me the altimeter also gave me a switch, shown in the photo. He said that when the lever is depressed, the switch is "off", and when the lever is up, it's "on". Left alone, the switch springs to the "on" position, as shown in the photo. If I use some sort of pin inserted from the outside to keep the switch depressed, then I could pull the pin to arm the device.

1. How would I attach the switch to the interior altimeter wall, position it, etc, so that a pin would have enough guidance and assurance of keeping the lever down? I have positioned the switch next to a piece of scrap tube in the orientation that I think things would need to be set up (but inside the tube, of course!).

2. In the shown position, the up-down motion of the lever is in the same forward/aft direction of travel of the rocket. This seems bad to me in case the g-force compresses the switch during liftoff, unintentionally powering down the device. However, imagine rotating the switch 90 degrees on its long axis (i.e., "rolling" the switch one side towards you in the photo). Then the switch lever would not have this problem. Is that advisable?

3. The switch has 3 prongs, numbered 1, 3, 2. It is my understanding that I attach the + and - wires to the 1 and 2 prongs (which way, or does it matter?) and I leave 3 alone. Is that right?

4. This whole pull-the-pin setup scares me because it seems sort of delicate. Would it be preferable to get a rotating key switch or a rocker switch that illuminates when "on"? If so, what's a good vendor link?

Thanks for any help you can offer.

switch1.jpg

switch2.jpg
 
geof
I do not like that type of switch I am afraid they will bounce during the flight creating problems for the electronics. I have used the Through Mount Slotted Switch from Aerocon with great success. I have also used the screw and magnetic switches from Featherweight and sold buy Aerocon. I have also used the switches sold by Missile Works.
Depending on the size of the rocket you are building Missile Works has some "printed mounts" for electronics that are pretty nice.

You did not say what electronics you are using so I really can't say if your wiring is correct. I would really need more info on the whole set up before commenting.
 
I personally wouldn't rely on this setup, and the switch is suppose to go between the battery and the altimeter. The way you have it drawn, the switch does nothing. You need a different type of switch and since it's your first time, I would recommend a wiring kit from Doghouse rocketry to help you learn the basics before you start designing your own setups. Others offer great altimeter bays wiring kits as well.

Check out Doghouse rocketry for the proper switch and wiring kits and battery holder would be my advice.

Just my two cents,
David
 
Thanks to both of you for the links.

Perhaps my sketch is misleading. I'm sure my wiring is right because every terminal on the altimeter has a label: Battery, Switch, Main, Drogue. And a +/- symbol. However, I'll triple-check the instructions, too.
 
The way you have drawn the switch is fine. You can also short the switch terminals and put the switch in line with the battery. I've done both.

My favorite switch is the Aerocon PVC switch:

https://aeroconsystems.com/cart/switches/pcb-screw-switch/

Once this is tightened down, it will not come loose. I solder the wires to the terminals on the switch, mount the switch in a block of wood (5/16 hole) and then pot the terminals in epoxy. The switch goes near the edge of the sled and is accessed from a hole in the airframe. The pic shows the front and back of the switches on different sleds (you don't need the white things though). This is a very reliable way to do switches.

Jim

DSCF0561 (2).jpg

DSC04025.JPG
 
I use the Featherweight magnetic switch with my RRC3s. Completely solid state, so nothing to mechanically fail, come loose, etc. Probably overkill, but makes me feel better. Plus I don't have to locate any external holes for a switch which gives me a bit more flexibility when making electronic bays. That being said, Jim's sent them over 100k, so if it works for him, it works.
 
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I use the Featherweight magnetic switch with my RRC3s. Completely solid state, so nothing to mechanically fail, come loose, etc. Probably overkill, but makes me feel better. Plus I don't have to locate any external holes for a switch which gives me a bit more flexibility when making electronic bays. That being said, Jim's sent them over 100k, so if it works for him, it works.

As it turns out, I've sent a couple of the mag switches over 100K too. I like many of the features of them. However, I tend subject my equipment to some pretty severe conditions, and over time, the mag switches can fail. There are some flights where I just can afford the chance that a switch might fail. The Aerocon screw switches don't fail.

On the other hand, I have a few smaller rockets that have the electronics in the nose cone. They have to be armed and then the nose cone installed and shear pinned. It works, but it's not ideal. Since it's a little easier to pull them down if there's a problem, those are great candidates for the mag switches.

Jim
 
As it turns out, I've sent a couple of the mag switches over 100K too. I like many of the features of them. However, I tend subject my equipment to some pretty severe conditions, and over time, the mag switches can fail. There are some flights where I just can afford the chance that a switch might fail. The Aerocon screw switches don't fail.

On the other hand, I have a few smaller rockets that have the electronics in the nose cone. They have to be armed and then the nose cone installed and shear pinned. It works, but it's not ideal. Since it's a little easier to pull them down if there's a problem, those are great candidates for the mag switches.

Jim

At the risk of sidetracking this, what is the typical failure mode for the mag switches? Best to ask and learn from experience than to learn independently in this case.
 
At the risk of sidetracking this, what is the typical failure mode for the mag switches? Best to ask and learn from experience than to learn independently in this case.

They just become more difficult to turn on and off, or just stop working. This isn't usually associated with any particular flight, but rather, the cumulative result of abuse. I guess I don't really know why it happens.

Jim
 
I ordered the screw-type switch recommended by JimJarvis50. It looks cheap, idiotproof, and easy to install. Thanks.


The way you have drawn the switch is fine. You can also short the switch terminals and put the switch in line with the battery. I've done both.

My favorite switch is the Aerocon PVC switch:

https://aeroconsystems.com/cart/switches/pcb-screw-switch/

Once this is tightened down, it will not come loose. I solder the wires to the terminals on the switch, mount the switch in a block of wood (5/16 hole) and then pot the terminals in epoxy. The switch goes near the edge of the sled and is accessed from a hole in the airframe. The pic shows the front and back of the switches on different sleds (you don't need the white things though). This is a very reliable way to do switches.

Jim
 
I checked out doghouse rocketry. Their hints page is very helpful.
 
I routinely use the Schurter switches that Bill sells at Doghouse. Clean mount through the airframe, no issues on more DD flights than I can count. Have also used the mag switches on 3" or smaller rockets, also no issues.
 
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