Proportional valve driver

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#1
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Hello All

I need circuit (or idea) how to drive proportional valve -10...0...+10V, using xmega D/A converter (0...3.3 V)

Ana

 

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A basic op-amp circuit, powered from +/-15v rails will do it.

 

You need to scale the 3.3v swing up to 20v, so a gain of 6, and then offset it by -10v. In reality, you do the offset first to give you -1.66 - +1.66v and then apply the gain.

 

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How many ma to drive the valve? Get a hi output opamp.

 

Imagecraft compiler user

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Valve spec says current is 10 mA.

I may need 4 D/A output, 2 for 0...+10 V and 2 for -10...+10V, so I will try DAC which can generate directly -10...+10 V (AD5722 or similar). Other 2 outputs (0...10V)  xmega D/A + opamp.

 

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I presume the valve slew rate is pretty slow in which case PWM -> LPF -> add -ve offset -> amplify -> buffer.

 

David