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neutral problem in circuit DC circuit

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FvM said:
Why would the clipped voltage affect LVDT operation? I don't believe that this is the case. The answer might depend on the details of synchronous rectifier used as receiver. Level stabilisation would be wanted however, because the drive voltage acts as scaling factor for the displacement measurement.
Click to expand...

Hello FvM ,

I am using full bridge rectifier at receiver end and a capacitor, which is use to read DC level

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Surender Reddy said:
Hi,



You need to isolate the circuit why don't you try with isolater.
Click to expand...


Which Isolation I have to use to Isolate analog signal. varying from +/- 15 V
 
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I am using full bridge rectifier at receiver end and a capacitor, which is use to read DC level
Click to expand...
Don't know the details of your LVDT transducer, but a usual type has zero output in the center position, a simple rectifier can't determine if the sensor is moved to the left or right.
 

If you want a precision LVDS, the frequency, amplitude and ratiometric detection is critical, so it doesn't change with core loading changes from motion.

clipping is not allowed.

For 0.1% typical accuracy on position use this.
https://www.mouser.com/ds/2/609/AD698-243309.pdf

For 25 or worse % accuracy
Try this.
image.jpg

Using a 10W audio power amp with a stable signal to drive it.
 

SunnySkyguy said:
If you want a precision LVDS, the frequency, amplitude and ratiometric detection is critical, so it doesn't change with core loading changes from motion.

clipping is not allowed.

For 0.1% typical accuracy on position use this.
https://www.mouser.com/ds/2/609/AD698-243309.pdf

For 25 or worse % accuracy
Try this.
View attachment 119067

Using a 10W audio power amp with a stable signal to drive it.
Click to expand...



Thanks SunnySkyguy ,

but this IC too much costly,

I have used same circuit as you shown in pic, but difference is that i'am using full wave rectifier instead of single diode.

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I am working on power supply of LVDT
 

The full wave is no different in accuracy as it is expecting a sine wave.
But it ought to be a precision rectifier Op Amp or use Schottky diodes with a large signal.

Your amp should be able to drive an 8 Ohm speaker with <1% source impedance, because the LVDT load can change with frequency, inductance and temperature.

Do you know what impedance is the load exactly?

The sensitivity for gain and offset errors will be high with unstable output levels. Fyi.

oh yah.. Dont use a 741
 

I am using TDA2030A instead of 741
 

Audioguru said:
An electronic circuit like your oscillator does not have a neutral. An electrical circuit has live, neutral and ground wiring.
You should learn that your circuit is wrong to be a Wien Bridge oscillator:
1) R1 and R3 must have the same value.
2) The gain must be a little more than 3 times.
3) An automatic level control circuit must be added so that the output level does not keep rising until the opamp produces clipping.

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Sine wave, AC circuit and Neutral?? Are you trying to make an inverter with a sinewave output? This way makes a heater that wastes a LOT of power from the battery.
But you could use a comparator to compare this sinewave (when it has its level stabilized) with a high frequency triangle wave and the output of the comparator will be Pulse Width Modulation making an efficient inverter.
Click to expand...



I am getting triangular wave using this circuit
 

The design of a lousy 741 opamp is 47 years old and was used for DC and low frequencies. At frequencies above 9kHz its high level "sinewave" output is actually a triangle wave because its output slew rate is too low.
Better and more modern opamps are perfect up to about 100kHz.
 

TDA2030A with Slew rate 8 V/µsec is ok for Sin wave upto 10kHz
 

The datasheet for the TDA2030A shows that it performs well up to 100kHz with a 4 ohm load and up to 200kHz with a load that is 50 ohms or more.
 

I don't recognize an obvious reason in the datasheet why TDA2030A won't work in this application. Although not discussed in the datasheet, there might be a problem that the amplifier isn't stable with closed loop gain < 3, as known for similar audio amps. But instability would show in high frequent oscillations rather than "triangle" waveform (you didn't tell the observed frequency). More likely, your circuit has wiring errors or wrong component values. Hard to debug from a distance.
 

The datasheet for the TDA2030A shows a gain of about 20 for all amplifier circuits so I think it should be used in this project to avoid oscillation and the amplitude of the sinewave generator should be attenuated to match it.
But I wonder why this TDA2030A power amplifier that is designed to drive a 4 ohm speaker is planned when the coil in the project was said to be 3k ohms that an opamp can drive?
 

someone know how to find , input current
 

yes , current required by my coil, in which I am feeding sin wave.
 

Unfortunately there's no driver coil impedance given, but 12 mA maximum is obviously the current specification.

I wonder where you got the 10 V rms driver voltage specification in post #5. I can't see it in the datasheet.
 


LVDT is just like transformer , can we calculate in put power, voltage and current , if we know output voltage and current.
 

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