Re: I need a little help with designing a Circuit!

On Wed, 25 Jan 2006 20:05:45 GMT, "Genome" <ilike_spam@xxxxxxxxxxx>
wrote:

>
><vesleharry@xxxxxxxxx> wrote in message
>news:1138152266.038244.273420@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>Hey I need a little help with designing/drawing a circuit. Can someone
>make me a sketch or help me with the solution?
>
>Here is the my problem:
>I'm going to make a measurement system for a bridge (AC bridge
>circuit). The measure-elements in the bridge can be resistive, for
>example: a Pt-100-element for measuring temperature, or a strain gauge
>for measuring pressure or power, or it can capacitive so that it can
>measure air humidity.
>The bridge is going to be driven by AC, and shall be square-,
>triangle-, or sinus-shaped. The frequency on the AC shall be in the
>area from 400Hz - 1kHz. The reason for using AC is because we can
>reduce influence of the amplifiers DC-error.
>When the bridge is driven by AC-voltage, then of course the bridge's
>output signal will be AC. And this output signal must be demodulated.
>And the method I supposed use, is with Phase Sensitive Detection.
>
>
>Task:
>· Make an oscillator circuit to drive/operate the bridge.
>· Make a necessary instrumentation amplifier by using op-amps.
>· Make a phase shift circuit.
>· Make a demodulator.
>
>Terms:
>· Assume that the bridge's output signal have amplitude = 2mV.
>· The signal bandwidth is DC to 10Hz, -1dB with 10Hz.
>· The measurement system shall be in the area 1.0V to 5.0V.
>· The measurement system accuracy shall be ±0.5% of full scale.
>· The measurement system resolution shall be 8 bits.
>
>Component:
>· Available supply voltage is +12V, -12V and +5V.
>· Available op-amps are uA741, OPA27, OPA177.
>· Available voltage reference is LM336.
>· Available voltage comparator is LM311.
>· Available analog switch is DG413DJ.
>· Available DA-converters are DA0808, DAC0832.
>
>
>Thanks in advance!
>
>
>You need to start out with a block diagram of your system. Paper is good for
>this if you have a pen.
>
>This is called top down design.
>
>Take one *** of paper and, from left to right, draw three boxes on it.
>
>Label the left box 'Input Drive'.
>
>Label the middle box 'Bridge'.
>
>Label the right box 'Measurement'.
>
>
>Or you can do it the other way around......
>
>Once you have done that then you have your top level design.
>
>BUT..... ask yourself 'What might be missing?'
>
>Hint, begins with C and is not Cuntrol.
>
>Throw your original piece of paper away and do it again but this time
>include the 'not Cuntrol' block.
>
>Does it look good?
>
>DNA
>

de-lovely ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

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