Instructables
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Picture of Pinch Valve
This is a simple way to control the flow of water via a microcontroller or similar. Most commercial irrigation valves require a certain amount of water pressure. This valve is designed for low water pressure. It is used in the eRiceCooker project, a fully automated system that cooks rice according to the frequency of news reports about genetically modified rice.

 
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Step 1: The Parts

Picture of The Parts
You will need:
- A servo motor
- Enough flexible latex tubing, outside diameter 3/8" (medical supply store)
- Metal pipe outside diameter 1/2" (home depot)
- Four zip ties (they can be a bit wider than the ones pictured)
- two tiny screws & bolts
- Flat material which can be cut, sanded and drilled (plexiglass, wood, aluminum, etc.)

Step 2: Assembling the Parts

Picture of Assembling the Parts
This is how the fully assembled valve looks from the front.

Step 3: Assembling the Parts

Picture of Assembling the Parts
This is how the assembled valve looks from the back.

Assembling the valve is really very simple:
- Cut the metal pipe in two even-sized pieces.
- Cut the plexi (or other material), so it forms an oval.
- Drill some holes in it, and attach it to one of the servo motor's arms using the screws.
- Push the latex tubing through the pipe-parts
- Attach the pipe-parts to the plexi.

Step 4: Open Valve

Picture of Open Valve
This is how it looks when the valve is open and the water flows.

Step 5: The Valve in the Context of a Larger Project

Picture of The Valve in the Context of a Larger Project
Once you've assembled and tested the valve, you can add some water.
maker127 years ago
I HATE MICRO,S (all haill nash for non micro based ic,s)
VelvetElvis8 years ago
Nice photos! I wish all Instructables were this clear.
cheesy8 years ago
Any suggestions on where to get cheap servos? Also, tips on hooking them up to microcontrollers?
bluelip cheesy8 years ago
Check your local RC/Hobby store. I picked up two Futaba S3004 servos last week for $13 each. I thought it was a good deal since the last time I bought a servo, a few years ago, they were over over 20 bucks each.
trebuchet038 years ago
oooo -I like that microcontroller setup (except it requires a programmer for initial setup :P) That site is acting a bit flaky (not sure if it's my end to blame) - I've been wanting to get into microcontrollers and I think this is how I'm going to do it (fits the budget :P).
Allow me to plug the Serial Wombat here. I picked one up a few months ago at Hamvention and it's pretty sweet: A programmed PIC that can act independently, but is mostly an I/O peripheral for your PC. It's incredibly easy to do tasks like drive steppers and servos, read encoders and pots, and control LCDs.
rimar20008 years ago
Excellent.
Crash21088 years ago
I was going to make an automated risotto maker.
LasVegas8 years ago
Love the automated rice cooker. Now can you make an automated potato masher? Or, better yet! an automated port roaster for every time a federal bill is passed.
ARVash8 years ago
Rofl XD. i like it :3