# Easy on/off switch for altimeter

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#### billdz

##### Well-Known Member
I'm finding it inconvenient to have to remove the payload section or e-bay to turn an altimeter on and off. I've done some searches and see there are several methods of easier on/off control, such as:
* push button switch activated by poking a rod through a hole in the airframe,
* wireless remote control, and
* screwdriver rotary switch mounted to airframe.

I'd be interested in hearing about any other tricks the gang has come up with.

On the remote control option, I see that Eggtimer's remote switch has been discontinued "due to the relative unavailability of suitable 4-button remote controls" (although I'm not sure why 4 buttons are needed just for on/off). The Eggtimer WiFi switch looks nice, although pricey. What about a cheap wireless switch from eBay, like one of these:
https://www.ebay.com/itm/292077177866?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT
or
https://www.ebay.com/itm/331926281858?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Thoughts?

#### DAllen

##### Well-Known Member
Run a pair of wires out of the ebay...Strip the ends, twist together and tape to the side of the rocket.

#### Coop

##### Well-Known Member
Had a lever switch I picked up from Radio Shack... positioned it so a thin dowel --actually, I think it's a bamboo skewer-- can be inserted to turn it off, removing turns it on. I positioned it so it's lever down, to keep from accidentally shutting off the system under G's. I have had no issues with it, but I don't think I'd do another this way. The Shurters do just fine by me.

Later!

--Coop

#### dmo

##### Active Member
What about a cheap wireless switch from eBay, like one of these:
The short answer is no.

The first unit is a 12V unit, and would require a 3s Lipo or similar. Does your altimeter support that high of a voltage? It might, or might not, work on 9V. The bigger problem is that it uses a mechanical relay. Relays and high G's do not mix well.

The second unit is only rated for a 1Amp load. Yes it would turn your altimeter on/off, but firing an e-match would almost always destroy the unit.

If you are handy with electronics, you probably could modify one to control a MOSFET to switch the power.

#### DavidMcCann

##### Well-Known Member
Run a pair of wires out of the ebay...Strip the ends, twist together and tape to the side of the rocket.
My favorite way to do it. Oh, just ummm... don't tape them to the BOOSTER... that's important. Tape them to the payload.

This little guy is on his way to mach 1.2 with the wires taped happily to the side-

here's a clearer photo of a tape job-

It's simply, easy, doesn't require fishing a screwdriver around, and isn't going to pull apart under G load (done it twice at 50G) and I'm lazy and hate soldering.

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#### FMarvinS

##### Well-Known Member
Bill- the ebay switches have several inherent problems: 1. Relays use relatively high amperage which causes battery failure relatively fast. 2. The relays used function under vibration & G-forces is not known and thus unpredictable. 3. The uncoded transmitter frequency used is the same often used in car R/C key bob transmitters and garage opener transmitters. Thus, transmitted frequency interference may lead to dysfunction. In my own trials-I found that the relay batteries (even new ones) didn't last. Furthermore, in my trials, I used a redundant screw switch and independent battery that often prevented a lawn dart occurrence.
Another alternative is the use of a cotter pin and female head phone switch jack. This was described by Tony (aka Tonimus) in one of his threads on his L2 flight of a Wildman Interceptor 98 AAD rocket. I have found rotary switches, screw switches, and recently the cotter pin/female head phone jack switches to be reliable.

Fred, L2
KG4YGP
ROSCO member

#### cerving

##### Owner, Eggtimer Rocketry
TRF Supporter
...

On the remote control option, I see that Eggtimer's remote switch has been discontinued "due to the relative unavailability of suitable 4-button remote controls" (although I'm not sure why 4 buttons are needed just for on/off). The Eggtimer WiFi switch looks nice, although pricey...

Thoughts?
The Remote Switch used a four buttons, you picked an 8-character arming/disarming code. That's 65,000+ possible combinations, it's not simply on/off. For some reason, the supply of the remotes dried up about six months after I started shipping them, so I was forced to stop selling them because anybody that didn't get a remote was probably not going to find a compatible one. Too bad, I personally liked the product a lot.

The WiFi Switch is $20, that's less than "other" electronic switches, and you get battery voltage, continuity status, and arming/disarming from over 100' away. Ask people who've tried them... they beat fumbling around with other switches by a mile. The only disadvantage is that they require a 2S LiPo and they do use a fair amount of power, but anything you're likely to put one of these switches into will probably have enough room for a decent battery (350 mAH or larger). #### mpitfield ##### Moderator Staff member TRF Lifetime Supporter Global Mod I use the featherweight Mag switch quite a bit but I am also now using two types of screw switches. From left to right my supplies of switches, Missleworks screw switches and the black things above are the screw switch guides, next up are some mini and heavy duty FingerTech robotics screw switches, to the right of them are the Featherweight Magnetic switches, and finally the last bag are the PerfectFlight snap action switches, that you can use with a pull pin. Also in that last bag you may notice some brass ferrules, these are used in small diameter nylon water pipe and work great for guiding the pull pin, I even have a bunch of the remove before flight tags I built an AV bay with the pull pin and it was a very clean setup, however I was never comfortable with the snap switch and felt that it may be susceptible to shock so I rebuilt the AV bay before the initial flight. So even though I used it, the rocket was not flown with it, so I cannot comment on their reliability from experience, but the others are golden. Last edited: #### Winston ##### Lorenzo von Matterhorn I'm finding it inconvenient to have to remove the payload section or e-bay to turn an altimeter on and off. I've done some searches and see there are several methods of easier on/off control, such as: * push button switch activated by poking a rod through a hole in the airframe, * wireless remote control, and * screwdriver rotary switch mounted to airframe. I'd be interested in hearing about any other tricks the gang has come up with. On the remote control option, I see that Eggtimer's remote switch has been discontinued "due to the relative unavailability of suitable 4-button remote controls" (although I'm not sure why 4 buttons are needed just for on/off). The Eggtimer WiFi switch looks nice, although pricey. What about a cheap wireless switch from eBay, like one of these: https://www.ebay.com/itm/292077177866?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT or https://www.ebay.com/itm/331926281858?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT Thoughts? Miniature DC barrel jack with integral switch. Mounted to airframe. Switch is closed when "remove before flight" barrel plug is removed. Example: https://www.digikey.com/product-detail/en/cui-inc/PJ-005A/CP-5-ND/165838 https://www.digikey.com/product-detail/en/cui-inc/PP3-002A/CP3-1000-ND/992136 #### Dave A ##### Lifetime Supporter TRF Lifetime Supporter I've always used the larger or smaller slide switches. Turned 90 degrees from the direction of the flight so G forces do not move it off. Easily armed/disarmed through the vent home with a small screwdriver of pen. #### ksaves2 ##### Lifetime Supporter TRF Lifetime Supporter I'm finding it inconvenient to have to remove the payload section or e-bay to turn an altimeter on and off. I've done some searches and see there are several methods of easier on/off control, such as: * push button switch activated by poking a rod through a hole in the airframe, * wireless remote control, and * screwdriver rotary switch mounted to airframe. I'd be interested in hearing about any other tricks the gang has come up with. On the remote control option, I see that Eggtimer's remote switch has been discontinued "due to the relative unavailability of suitable 4-button remote controls" (although I'm not sure why 4 buttons are needed just for on/off). The Eggtimer WiFi switch looks nice, although pricey. What about a cheap wireless switch from eBay, like one of these: https://www.ebay.com/itm/292077177866?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT or https://www.ebay.com/itm/331926281858?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT Thoughts? Number one is 12 volts and not practical. I did use a set of these to switch a relay to feed 12V car/marine battery to a rocket igniter! Calm down, the transmitter that controls a similar receiver has a switch block to set a code which makes this quite safe. I train the receiver to "hear" the coded transmission to activate the relay. The relay in those receivers can only handle 10 amps so I have it switch on another relay in the remote 12V car/marine battery box that feeds the high current to the rocket. I do not have a "key" interlock but I scramble the switchblock in between flights. I've thoroughly tested and it passes muster in my book. I know a club that uses one of these too. I built mine for$75.00 back in the day. Unfortunately
the switch coded transmitter isn't available anymore. RfRemotech was the dealer.

Number two is only good if you come up with another circuit to switch on the battery. It just sends a small pulse signal that can activate the actual current switch. The device by itself won't work. Kurt

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#### ksaves2

I've always used the larger or smaller slide switches. Turned 90 degreesView attachment 317770 from the direction of the flight so G forces do not move it off. Easily armed/disarmed through the vent home with a small screwdriver of pen.
Have seen some put those facing the outside of a rocket for easy on/off approach. Yeah, yeah, yeah. I know one is going to say "G" forces but several reputable folks who have done this swear they've never had any issues and makes it easy to
inactivate the electronics when the flight is recovered. They do mention it's important to purchase a good quality switch and not some Radio Shack special. Haven't done it myself but I'm leaving myself open to it in the future.
BTW, nice machined metal bulkheads you got there Dave. Kurt

#### Banzai88

##### Lvl 1,Wallet....Destroyed
TRF Supporter
Purchase Ball head drivers and replace the Phillips screw with a socket head screw. I found I couldn't "feel" the Phillips screw easily and destroyed a switch one time that of course aborted the launch. Put a 2-56 socket head in and have had no
problems since. Kurt
This, along with the little black thingys that funnel the driver onto the screw head. Makes it super easy every time.

#### JimJarvis50

##### Well-Known Member
My favorite switch is the "pvc screw switch" from Aerocon.

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

The switch has only one moving part - the screw itself. The screw is tight enough such that it won't back out one tightened down. I have used somewhere on the order of a hundred of these switches on multiple hundreds of flights. I have only had one problem when a switch was supplied that was obviously defective. The pics show one version of what I do, which is to mount the switch on the altimeter bay skid for access through the air frame. The electronics can be activated with the bay installed or with it outside of the rocket. There are no wires to route or connect through or to the air frame. As shown in the pic, I also pot the wires from the back of the switch so that they can't come loose. Simple and reliable.

Jim

#### Titan II

##### Well-Known Member
This, along with the little black thingys that funnel the driver onto the screw head. Makes it super easy every time.
This is the one Missile Works sells for their screw switches. Not only does it funnel the screw driver into the screw, it also keeps the screw from backing out of the switch. This one will not fit the Featherweight switches.

#### Handeman

##### Well-Known Member
TRF Supporter
Had a lever switch I picked up from Radio Shack... positioned it so a thin dowel --actually, I think it's a bamboo skewer-- can be inserted to turn it off, removing turns it on. I positioned it so it's lever down, to keep from accidentally shutting off the system under G's. I have had no issues with it, but I don't think I'd do another this way. The Shurters do just fine by me.

Later!

--Coop
I did the same thing. This is the pic of the av-bay for my L1 cert rocket.

I used the brass tube from the ink tube for a ball point pen. After the epoxy shown broke, I ended up using J B Weld to epoxy the tube to the board. It held up to a couple of 80G flights with I1299 Warp 9 loads.

I went to screw switches for my L2 rockets, but went back to the pull pin switches like this for my L3 and the ones I've built since. I'll probably stick with them. I use a screw switch as the Master On/Off power switch in the shoulder that fits in the booster section. The pull pins are in the switch band or av-bay vent holes. That way I can turn the altimeters on and off on the bench with just the screw switches, but when I get to the field, I insert the pins, turn on the screw switches and put the rocket together. On the pad, I just pull the pins and it's on.

#### billdz

##### Well-Known Member
Thanks for the replies, folks. Lots of ideas, still not sure which way I'll go. Looks like the Eggtimer WiFi Switch is the only wireless option at this time. I was thinking wireless since my TeleMetrum moves from rocket to rocket.

#### KenRico

##### 'Just the Tip'
I bought a couple of eGGtimer WiFi switches when they hit to use with my altimeters.

Now i buy the Altimeter with the built in Wifi switch ..the eGGtimer Quantum , saves the continuity wiring between my old altimeters and the switch, and its less expensive than the commercial deployment altimeters out now.

Kenny

#### Bat-mite

##### Rocketeer in MD
Magnetic switches are great for smaller rockets where there is little to no room to have a big switch sticking through the wall. But you have to be very careful to mark the airframe where the magnet is, or else you will be standing at the pad for a long time, trying to find the magnet. Also, elevate the mag switch so that it is close to the coupler wall.

#### rms

##### Well-Known Member
In the last few builds, I have started mounting missleworks or featherweight screw switches to a piece of body tube mounted on the alt sled. This allows the sled to be pulled out without the aggravation of wire connected to the rocket body. The switches line up with the av bay sampling holes to allow ease of activating.

#### Bat-mite

##### Rocketeer in MD
In the last few builds, I have started mounting missleworks or featherweight screw switches to a piece of body tube mounted on the alt sled. This allows the sled to be pulled out without the aggravation of wire connected to the rocket body. The switches line up with the av bay sampling holes to allow ease of activating.
Cool idea.

#### kcobbva

I've become very fond of the Mag Switch, but as Bat-Mite suggested, you need to mark your sweet spot to arm it at the pad otherwise your moving the magnet all over the place to get it to turn on. I have two mounted in one rocket and very specific marks so I can turn on each individually.

#### billdz

##### Well-Known Member

It's not...
12V is too high for most altimeters..
My post wasn't for the device..
It was for the keychain remotes..
I have quite a few of Cris Eggtimers remote switches,,
I really like em..
He is right though,,
I used to buy these remotes many ways,, many different ads on ebay..
Not as prevalent as they were..
But you can still get em...
I vote we get a petition together and all sign it to get Cris Eggtimer to bring back the remote switch....lol...

( man, is he gonna kill me,, lol )

Teddy