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 Posted: Jun 27, 2012 - 05:31 PM |
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Joined: Jun 27, 2012
Posts: 3
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| I'm new to the forum and just looking for a simple circuit to convert a PWM signal from my controller to actuate a +12/-12VDC actuator valve. |
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Posted: Jun 27, 2012 - 06:17 PM |
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Joined: Nov 22, 2002
Posts: 12036
Location: Tangent, OR, USA
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Two questions:
1) What do you mean by +12/-12VDC?
2) Why PWM for an actuator valve? Is it a proportional valve or is it an on/off valve?
Jim |
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Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA
"The only thing standing between us and victory is defeat" P.G.Wodhouse in Wooster & Jeeves series
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Posted: Jun 27, 2012 - 07:47 PM |
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Joined: Sep 04, 2002
Posts: 21251
Location: Orlando Florida
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Posted: Jun 27, 2012 - 08:03 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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This must be quite a big opamp to drive the valve (and heat the universe), so most people prefer using the H-bridge driver instead  |
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Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
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Posted: Jun 27, 2012 - 08:13 PM |
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Joined: Sep 04, 2002
Posts: 21251
Location: Orlando Florida
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| If its a spool valve it might only draw 20ma, could be driven with one of those 1A opamps like an OPA859 |
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Posted: Jun 27, 2012 - 09:07 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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| Could be. But shouldn't be |
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Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
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Posted: Jun 28, 2012 - 12:37 PM |
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Joined: Jun 27, 2012
Posts: 3
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I appreciate all the comments!
Jim -- the valve is an ON/OFF ball valve, +12V to open and -12V to close. I assumed there is an internal relay on the actuator to turn the motor on/off. The current is less than 1A.
I need to integrate the valve control to the main machine controller and the only option is PWM.
THANKS A LOT! |
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Posted: Jun 28, 2012 - 02:24 PM |
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Joined: Dec 22, 2006
Posts: 300
Location: Odense, Denmark
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I imagine that you have just two connections on your valve and that you need to apply the voltage in one direction to open it and in reverse to close it... Right? (See the attached image)
If this is in fact the case you could just use a simple H-bridge and a simple single-supply 12V to control the valve! There are plenty of 5V input compatible H-bridge ICs (I have used L6203 my self). |
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Posted: Jun 28, 2012 - 03:50 PM |
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Joined: Sep 04, 2002
Posts: 21251
Location: Orlando Florida
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| Two outputs and two mosfets. |
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Posted: Jun 28, 2012 - 04:00 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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bobgardner wrote:
...and two mosfets.
...per output |
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Posted: Jun 28, 2012 - 04:14 PM |
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Joined: Sep 04, 2002
Posts: 21251
Location: Orlando Florida
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| Seems like 'turn on A' or 'turn on B' one at a time just needs one mosfet per output? |
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Posted: Jun 28, 2012 - 04:20 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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spacejunk29 wrote:
the valve is an ON/OFF ball valve, +12V to open and -12V to close. I assumed there is an internal relay on the actuator to turn the motor on/off.
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Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
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Posted: Jun 28, 2012 - 06:31 PM |
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Joined: Jun 27, 2012
Posts: 3
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| Thanks for all the suggestions! May be I will try the opamp option and see what happen. |
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Posted: Jun 28, 2012 - 07:03 PM |
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Joined: Nov 22, 2002
Posts: 12036
Location: Tangent, OR, USA
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Full H-bridge would do it. You can the PWM it to make it variable.
One valve control wire goes to one H-bridge terminal and the other control wire goes to the other H-bridge terminal. Power the H-bridge from 12V.
Very few parts, pretty easy to do. Single supply. Not expensive (a reasonably good H-bridge with this kind of rating can be gotten for less than $5US). Direct drive from any micro.
Jim |
_________________
Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA
"The only thing standing between us and victory is defeat" P.G.Wodhouse in Wooster & Jeeves series
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Posted: Jun 28, 2012 - 07:11 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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spacejunk29 wrote:
Thanks for all the suggestions! May be I will try the opamp option and see what happen.
Don't! Just don't. |
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Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
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Posted: Jun 28, 2012 - 07:21 PM |
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Joined: Nov 22, 2002
Posts: 12036
Location: Tangent, OR, USA
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Agree, finally, MBedder on this one.
An op-amp is UGLY. It takes two big supplies. It makes lots of heat. It is expensive. Lots of parts.
Its not good.
Jim |
_________________
Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA
"The only thing standing between us and victory is defeat" P.G.Wodhouse in Wooster & Jeeves series
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