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2 Position Servo Controller Answered

I need some help, I am trying to create a damper control using a servo and a 555 timer. Is there anyway that you can use a 555 timer to make a servo move back and forth between 2 positions (0 degrees and 90 degrees) with an with and on/off signal and not a pot? So when the thermostat sends power, the damper moves to 90 degrees, then when the thermostat shuts off the servo returns to 0 degrees?

Thanks for the help in advance.
-Ryan

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panos.spyropoulos.3

3 years ago

Buy a cheap servo tester. They usualy have 3 modes. Center, potentiometer, and swing. Re-wire with a switch to go "on" on the center position and "off" on the potentiometer position setting it to 90 degrees, canceling the swing position and there you go. But for such a simple project I would use a 90 degree rotary solinoid.

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steveastrouk

6 years ago

If this damper is supposed to be "on" all the time, you'll kill the servo in a matter of months.

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mpilchfamilysteveastrouk

Reply 6 years ago

Good point.

He may need to use a micro controller instead of the 555.

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steveastroukmpilchfamily

Reply 6 years ago

It's still going to jitter and break if you leave the power on it. For two positions, its MUCH simpler to use two microswitches and a couple of diodes, and just make the servo into a dumb motor and gearbox.

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mpilchfamilysteveastrouk

Reply 6 years ago

Sounds like he wants the Thermostat to trigger the servo. That being the case he'll need more then a couple of switches. But i agree it would be easier to go manually and operate it with switches.

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steveastroukmpilchfamily

Reply 6 years ago

Hmm. OK, add a relay ;-)

All he needs is to reverse the voltage to the damper to make it move one way, and back to move it the other.

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WingmanSVTmpilchfamily

Reply 6 years ago

how easy would this be to do with an arduino. Never used one before either, I was trying to do it electronically rather then a micro controller because I do not how to write the code for it.

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mpilchfamilyWingmanSVT

Reply 6 years ago

Check the Arduino web site. Also look at the forums. There are allot of very helpful people there that can get you started on the right track. Be sure to do a search of the forums or even on google. You may find someone has done a similar project that can be adapted to your needs.

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mpilchfamily

6 years ago

Sure just replace the pot with resistors set to the values needed to hold the servo at the angles you want. Set the circuit up on a breadboard with a pot. Have the servo in the 0 degree position and take the resistance reading. Move it to 90 degrees and get the resistor reading. Now you have the resistor values needed.

There may be a better way to wire it but here is what i would do. Use a relay to toggle between the 2 positions. The controller circuit will receive power all the time. The servo won't move till the thermostat turns on or off. When the thermostat turns on it powers the coil on the relay moving the switch to the 90 degree resistor thus moving the servo. When the power is cut the relay goes back to its original position allowing power to the 0 degree resistor returning the servo to its home position.

Here is a ruff schematic for you. With and without the pot.

servocon.gifservocon.jpg
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WingmanSVTmpilchfamily

Reply 6 years ago

Thank you that helps me out alot. This is my first time working with the 555. Is there a tool for choosing the resistors/caps/transistors to use in that 555 circuit?

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mpilchfamilyWingmanSVT

Reply 6 years ago

Do a google search for 555 Servo Controller. You'll find many variations of 555 servo controllers.

What steveastrouk said is true. The method i mentioned would wear out the servo rather fast. You'll need to figure out how to turn off the controller when no t in use. The simplest option would be to set the damper up to be operated manually. Then you can turn it on as needed and flip it open or closed then turn it off.

Or you can get into the exciting world of micro controllers and do everything with an Arduino. The Arduino would detect when the Thermostat wants the damper open, opens it up then cuts the power. The same when it needs to close.