Senior Design Team 181

Oscillator/Demodulator to Fit on Flexible PCB

www.transtekinc.com

Team:• Ryan Williams (EE)• Jonathan Wolff (EE)• Damon Soto (EE)• Jason Meyer (EE)

Advisor: Helena Silva (ECE)

Trans-Tek Contacts:• Mark Bennett• Jeffrey Gladu

Introduction

• Trans-Tek Background• Linear Variable Differential Transformers (LVDTs)• Current Oscillator/Demodulator Models• Goals• Oscillator• Demodulator• Timeline• Budget

Outline

• Founded in 1967• Located in Ellington, CT• Leading manufacturer of Linear and

Angular Displacement, and Linear Velocity Transducers

• Use Linear Variable Differential Transformers (LVDTs)

• Applications in position and velocity sensing

Trans-Tek

• Consists of a 3-part transformer

• Secondary coils wired in subtractive configuration

• Position of core determines output voltage

• Linear relationship between core position and output voltage http://upload.wikimedia.org/wikipedia/commons/0/07/

Lvdt_how.gif

LVDTs

LVDTs

http://upload.wikimedia.org/wikipedia/commons/5/57/LVDT.png

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Uses of LVDTs

Oscillator/Demodulator Models

• Model of Focus: • Series 1000

Oscillator/Demodulator

• Issues:• Size• Digital Signal Processing (not

used currently)

• Re-Engineer• Using specifications provided

to us by Trans-Tek• Size constraints, input/output

and component hardware

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Oscillator/Demodulator Models

www.transtekinc.com

Goals• Use Digital Signal Processing (DSP) preferred over

hardware method.• Size Restraint: 0.700” DIAMETER TUBING, LENGTH T.B.D.• Series 1000 Oscillator Demodulator

• Maintain accuracy and reliability• manipulate product dimensions

• Oscillator:• maintain sinusoidal output, <1% harmonic distortion

• Demodulator:• Maintain non-linearity <.03%

Oscillator

• Hardware circuit that converts a DC signal to an AC signal.

• Frequency of the oscillator is determined by a RC combination, looking for a range of 1.5 to 12.5 kHz.

• Output voltage determined by a resistor, looking for 1 to 6 VRMS.

• Need to make an oscillator with almost no harmonic distortion.

http://www.electronics-tutorials.ws/oscillator/osc22.gif

• Can be performed using a hardware circuit or DSP• Hardware Circuit• No coding required• Same process used in

current models• DSP• Easier to modify and tune• More accurate• No circuit components

needed

http://www.singer-instruments.com/sites/default/files/images/tutorials/how_lvdt_works_fig3.gif

Demodulator

• Input impedance of 1MΩ or higher• 4 separate selectable output

ranges• Ripple voltage less than 0.2%• Non-linearity less than 0.03%• Temperature coefficient best effort

(± 1%)

Demodulator Specifications

Timeline

September October November December January February March April MayMeet with Sponsor Project Statement Project Specs Proposal Presentations Research Parts Written Proposal Schematic Order Parts Protoboard Build Final Presentation Final Report Debug PCB Build

Inventory•Flexible PCB •Microcontroller •LVDTs •Proto Board for experiments • 0.7 inch tubing•Component parts for the Ocillator/Demodulator •Other Parts TBD

Budget• All required materials supplied by Trans-Tek• Need to buy:• Flexible PCB• Microcontroller/DSP• Component parts for proto-board and PCB

• Total will amount to < $1000

Questions?