Break Wire How To?

[DAllen]

I am probably over thinking this but...I just got a PF timer and it uses a break wire for activation. Does anyone have pictures of how you do yours or any other information on techniques?

Like I said...probably over thinking this one...

[troj]

No pictures, as I no longer have the device where I used one...

What you need is a way to open a circuit to trigger the timer.

On mine, I ran a pair of leads from the rear of the rocket up to the electronics bay. The leads were then connected to the altimeter's breakwire connector.

Once the rocket was on the pad and otherwise fully ready, I then attached a jumper cable to one of the connectors on the rocket, ran it down, wrapped it around a leg on the pad, then back up to the other connector.

This way, when the rocket began to move, the breakwire would be pulled loose of the connectors, opening the circuit.

-Kevin

[H_Rocket]

I use two different methods for rigging a breakwire

1. 40 gauge wire wrap wire works real well. it is strong enough to handle and fragile enough to break reasonably easy (requires about 5-10 pounds of force).

2. Thin solder also works well. One trick here is to place it across the nozzle of the motor you want to trigger off of. This works well for situations where you want to make sure the main motor lit.

Keep in mind you can also rig a MT3 to start timing on circuit close as well as open. Not as useful, however it is some added flexibility to consider. Works OK for cascading timers.

[rdbones]

Once the rocket is fully ready to fly I use a piece of solder between the contact points with a piece of thin steel cable attached to the solder and the launch tower.

The rocket moves and the steel wire pulls through and breaks the solder. Just have to make sure you use a strong enough piece of solder to hold the weight of the cable but still break when the rocet moves.

I will see if we have any pictures of this later today and post if we do.

[troj]

One thing I'll add is that breakwires need to be handled with care -- once armed, if you need to approach the rocket for any reason, it's important that the first thing done is disarming the device using the breakwire.

The last thing you want to do is inadvertently trigger the breakwire and active an ejection or staging timer.

-Kevin

[DAllen]

One thing I'll add is that breakwires need to be handled with care -- once armed, if you need to approach the rocket for any reason, it's important that the first thing done is disarming the device using the breakwire.

The last thing you want to do is inadvertently trigger the breakwire and active an ejection or staging timer.

-Kevin

Helpful posts no doubt. I will definitely have a switch on the timer itself to disarm it in the event I need to install a new ignitor in the main motor.

Has anyone used some sort of male/female connectors to separate at liftoff? Something like this?

http://www.radioshack.com/product/in...lickid=prod_cs

I think if you get the connectors orientated vertically it should work. Grease 'em up a bit and they ought to dissconnect easily.

I'm beginning to think that a pair of wires loosely twisted together around one of the pad legs might be the best option. Getting a line of solder to stay put on a small 29mm nozzle is problematic especially in the winter when things like masking tape don't stick very well.

-Dave

[H_Rocket]

A Quickconnect like that will have way more pull strength than you probably want in this case. They are designed to stay together and have multiple mechanical grip points.

[dixontj93060]

I'm beginning to think that a pair of wires loosely twisted together around one of the pad legs might be the best option. Getting a line of solder to stay put on a small 29mm nozzle is problematic especially in the winter when things like masking tape don't stick very well.

I vote "yes" to the twisted wire.

[RandyM]

I'm beginning to think that a pair of wires loosely twisted together around one of the pad legs might be the best option. Getting a line of solder to stay put on a small 29mm nozzle is problematic especially in the winter when things like masking tape don't stick very well.

-Dave

IMO, that is your best bet. it works and it's simple.

[ClayD]

IF you could mount a phono jack , you could use a headphone jack on the pad and it would just break contact when it lifts off...Put an LED in line in line with the headphone jack so you know when its plugged in, making good contact.

but a couple wires is - cheapest...

[troj]

I used a male DB-9 mounted on the rear of the rocket. I then used a length of wire with female DB-9 terminals crimped on. They hold their own weight nicely, but slip off very easily when the rocket moves. And they're cheap enough that the part on the pad is disposable, if it gets damaged.

-Kevin

[JDcluster]

You can , but have make sure you get the correct one. Some are normally open circuit & others a normally closed.

The correct one would be normally open so when you pull the plug out it closes or completes the circuit.


JD

IF you could mount a phono jack , you could use a headphone jack on the pad and it would just break contact when it lifts off...Put an LED in line in line with the headphone jack so you know when its plugged in, making good contact.

but a couple wires is - cheapest...

[Rocketjunkie]

The few times I've used a breakwire I run it under the motor and let the motor burn through it. I use 30 gage wire wrap wire.

[DAllen]

I've used 1/8" phono jacks as arming switches for my altimeter. They can be wired either way - normally open or closed. The only way to really tell which is which is with a voltmeter on the resistance setting thingy. Let's just say I'll never do that again because it seemed iffy as to whether or not they'd work consistantly and for the amount of fuss and bother involved installing the contraption sure made twist and tuck look more appealing. Maybe I got a couple that were pretty crappy but even with good ones I imagine that any exposure to dirt or an exhaust plume would make the connection garbage.

-Dave

[dixontj93060]

I've used 1/8" phono jacks as arming switches for my altimeter. They can be wired either way - normally open or closed. The only way to really tell which is which is with a voltmeter on the resistance setting thingy. Let's just say I'll never do that again because it seemed iffy as to whether or not they'd work consistantly and for the amount of fuss and bother involved installing the contraption sure made twist and tuck look more appealing. Maybe I got a couple that were pretty crappy but even with good ones I imagine that any exposure to dirt or an exhaust plume would make the connection garbage.

Yes, phono jacks are good for non-critical connections such as a siren or a momentary closure/transition, but that is about it.

[rdbones]

Helpful posts no doubt. I will definitely have a switch on the timer itself to disarm it in the event I need to install a new ignitor in the main motor.

I'm beginning to think that a pair of wires loosely twisted together around one of the pad legs might be the best option. Getting a line of solder to stay put on a small 29mm nozzle is problematic especially in the winter when things like masking tape don't stick very well.

-Dave

If your rear closure has been drilled for a safety wire it is real easy to get the solder or wrap wire approach to work ...... No tape needed.

[bobkrech]

I used a male DB-9 mounted on the rear of the rocket. I then used a length of wire with female DB-9 terminals crimped on. They hold their own weight nicely, but slip off very easily when the rocket moves. And they're cheap enough that the part on the pad is disposable, if it gets damaged.

-Kevin

Bingo!

Another way is to have 2 male DB-9 pins with crimps attached to the bottom of the rocket and use 2 female crimp sockets attached by a short piece of wire that is tied to one of the launcher legs. When the rocket lifts off, the female pins stay attached to the pad, breaking the continuity and triggering the timer. Best part is the female breakwire always stays attached to the pad.

Bob

[DAllen]

Bingo!

Another way is to have 2 male DB-9 pins with crimps attached to the bottom of the rocket and use 2 female crimp sockets attached by a short piece of wire that is tied to one of the launcher legs. When the rocket lifts off, the female pins stay attached to the pad, breaking the continuity and triggering the timer. Best part is the female breakwire always stays attached to the pad.

Bob

You know, I seem to remember seeing a 3/4 scale Patriot at LDRS27 that looked like it had DB-9 connectors on the bottom of it and I wondered what the heck that was all about...now I think I know.