SpudFiles

The thing HAD a motor right?
I'd simply use the lazy bastard thing too.

Sensor is tripped, relay activates. power goes to sprinkler valve,

-relay is not powerful enough and fries.
-relay is powerful but wont actuate.
-Relay/transistor cascade costing alot of money.

It all boils down to weather or not you can even find a suitable relay. In essence it's the exact same thing, using a motor instead of a magnetic coil. The advantage of the motor-button setup is that you don't have to worry about frying the button, plus there's just a heck of a lot less head scratching to do. Relays and transistors are nice, as long as you designed what you're building around the components, not building something and looking for parts 'lego-bin style'.

You basicly want a 2pole lighting contactor with a 6 volt coil, Normally open.

Check into Jandy Pool Products 3HP relay. They operate at 10v dc and control up to 240v.

http://www.a1poolparts.com/-strse-376/Detail.bok

Don't think that you'll get the range that you want. I suggest something like kipkay shows on metacafe using a laser, mirrors, and a light sensor. Would not be that hard to set up a mine and 1 mirror reflecting on the sensor.

that's really cool, i cant wait to see it finally finished, and two 9v will give you 18v, that question is probably already answered though, this will be fun for your matches

Davidvaini wrote:Hey guys, I decided that I wanted to make some motion detection mines for the use of Airsoft.

The plan is as follows, The Glade motion sensor circuit from the Glade Sense and Scent product found here, will be used to detect motion of enemy troops. Once the sensor detects the movement, it sends an electric signal to a relay. The relay acts as a switch to allow higher voltage (18v) to activate a sprinkler valve.

I read through the list of posts and found the main issue was dealing with the higher voltage and current of the sprinkler valve. Inexpensive parts will do the trick without mechanical motors or relays. A MOSFET, a diode, a resistor and a battery box and you are good to go.

Use an N channel Enhancement mode power FET. One stolen from an old car power amplifier will work if it isn't fried.

Connect the output of the glade sensor to the Drain and Gate with a ~10K resistor. Experimentation will be needed to find the correct polarity to "Turn on" the transistor.

The Positive power of the valve battery is connected to one lead of the valve. The other lead of the valve connects to the Source of the transistor. The battery minus lead connects to the Drain of the transistor. The diode is connected between the source and drain of the transistor so the valve inductive kick doesn't destroy the transistor. The cathode goes to the Source (+ Side) and the anode connects to the drain and battery minus.

When the glade sensor sends out 5 volts this will be enough to turn on the power MOSFET and turn on the sprinkler on the higher voltage battery.


I picked up mosfets in bulk for 35 cents each a while back. They are not expensive and are common in radio control cars and stuff with electronic throttles.

I know this a little old but I would suggest using simple transistor biasing and 3 nine volts.

Davidvaini

That's a damn clever idea, and great shoping to!

It shouldn't be that hard to find a suitable relay. Indeed, there's a chance that standard 12V relays will work with just 4V.

Here's a couple ~5V relays from RadioShack;
http://www.radioshack.com/product/index ... Id=2062480
http://www.radioshack.com/product/index ... Id=2062478
The first one's coil is rated at 5V, 90mA, 55Ohms and should work fine on a 4V circuit that had enough oomph to run a small motor. The contacts are rated for 1A at 125VAC. That is more than enough to handle the power of a 24VDC solenoid.

From All Electronics:
http://www.allelectronics.com/make-a-st ... LAY/1.html
http://www.allelectronics.com/make-a-st ... Y/-/1.html

These relays cost from about $1.5 to perhaps $5 each.

Regardless of the voltage rating of the relay's coil you really only need to worry about three things:
1. Can the control circuit source enough power (VxI) to operate the relay without frying the control circuit. Since your circuit is meant to power a small motor it can probably source a decent amount of power.
2. If the relay's coil is being operated at a voltage significantly different than what it was designed for then the coil may have heating issues. In your application it probably doesn't matter since the relay is only turned on for a second or so and that happens infrequently. With a duty cycle this low the relay's coil will tolerate being operated out of spec.
3. Back EMF from the coil when power is turned off can potentially damage the control circuit. It's a good idea to include a reversed biased diode across the relay's coil to protect the control circuit.

Isn't the circuit is powered by a pair of AA batteries? Where is it getting 4V from? Looks to me like you need a 3V relay.


The detector might be useable in the infrared range.... check and see if it has an IR filter on it. Many optical detectors are pretty sensitive in the near IR, some well into the far IR (heat) range. It's pretty common for manufacturers to include an IR filter over the detector. Can you trigger the dtector with the beam from an IR remote control?

Is the detector down in the black tube next to the orange LED in the photo's? I wonder if it is a phototransitor, photodiode or just a CDS cell.