Questions about electronic triggering of a sprinkler valve

[potatoflinger]

I came up with an idea for a remote triggered airsoft weapon, but I have a question about the electronics.

I want to use the electronics from an old r/c plane to trigger a sprinkler valve since that is what I have available without spending money. I don't know very much about electronics, but I'm pretty sure that I need to use a relay for this to work. My plan is to disconnect one of the plane motors, and hook the wires up to the relay, then have three 9-volt batteries connected to the same relay so that when I press a button on the plane's remote, it completes the circuit with the 9-volts which triggers a sprinkler valve.

My question is, what type of relay should I look for? I don't know much about electronics so I have no idea what the different types of relays are for, or how much electricity they can handle.

All help is much appreciated.

[irisher]

Sounds like you need to do some research into transistor biasing.

[Technician1002]

An electronic speed control with Battery Eliminator circuit for conventional (brushed) motors works fine on higher voltages. Sprinkler valves work fine on 2 9 volt batteries. Do not use a speed control for a brushless motor. An electronic RC relay for operating landing gear solonoids is another option.

With the BEC circuit, you can eliminate the receiver battery pack and run it entirely from a pair of 9 volt transistor batteries.

[potatoflinger]

I don't really know how either of those suggestions would work for my purposes. Maybe I should have been a little more clear about what I am trying to do. The only purpose of the r/c plane electronics is to give me the parts I need to make the remote wireless. This thing will not be leaving the ground.

I tried it with a relay I found at Radioshack and it seems to be working the way I wanted it to, even if it is a little bit more complex than it has to be.

[Technician1002]

Using the RC receiver from the plane and the speed control for the motor (if electric) the radio can be used for wireless control of a sprinkler valve instead of an electric motor.

Many RC planes use 7.2, 12, or higher for the motor and don't use a 4.6 volt receiver pack, but instead use a battery eliminator in the speed control to power the receiver from the higher voltage motor battery. This configuration is called a battery eliminator as it eliminates the need for a separate receiver battery pack.

A 2 wire to the motor must be used. A 3 wire control for a brushless motor is the wrong one to use to power a sprinkler valve.

[iknowmy3tables]

it's easy, take the leads going to the motor, turn on whatever switch you need to turn on in the control panel, use a multimeter to test the voltage and direction of current and wire it up like this

positive motor lead+===-additional battery+===-solenoid+===-negative motor lead

you can just use the rc vehicle's circuit as a remote control switch, just be careful not to overload it. It's simple, these guys have been trying to tell you that you should be able to do this and add just enough battery power without burning up the circuit

[irisher]

@ikmt Must R/C circuit boards will most likely not take 27 volts.

[iknowmy3tables]

that's true especially with a tiny RC plane circuit, but like people have mentioned you shouldn't need 27V to trigger the solenoid,

[Technician1002]

What voltage did the original model plane use for the motor? If it used 2 9.6 volt RC packs or 2 7.2 volt packs, it may already be 14.4 or 19.2 volts, both plenty to operate a sprinkler valve. Tell us more about the RC electronics. What plane was it? What motor and batteries did it use? I don't know what electronics you have at this point.

A standard 3 wire Digital Proportional radio control system is able to interface with most off the shelf RC electronic throttles, including high voltage high power ones. This is often used in robotics to run higher power stuff such a wheelchair motors, electric power window motors, etc.

Be sure to use a speed control that has only 2 wires to the motor for a brush type motor. The 3 wire brushless controllers won't work for this application.

This one will handle 18 volts and has the battery eliminator.
http://www.robotcombat.com/products/0-SABER2X5-RC.html

[potatoflinger]

Okay, to clear up some of the confusion, the plane was a piece of junk from the start and is probably quite a bit different from what you guys are thinking.

The plane was one of those remote controlled planes that had one button on the remote, and all the plane would do is fly in circles, gaining a little bit of altitude when you pressed the button on the controller. It was the kind of thing where you had to plug the plane into the controller for a couple of minutes to charge the plane's battery enough for a few minutes of flight.

The rechargeable battery in the plane was 2.4 volts, so I replaced it with two rechargeable AA batteries that were 1.2 volts each. I took out the motor and replaced it with a relay, and the relay controls a separate circuit with two 9 volt batteries and the sprinkler valve.

So far it is working exactly the way I wanted it to. The only thing I haven't done is hook up the cannon and sprinkler valve, I have just been using a siren in place of the sprinkler valve for testing.