BANDPASS FILTER CIRCUIT DESIGN

The Circuit Designer's Companion, Second Edition (EDN Series for Design Engineers)

Tim Williams' Circuit Designer's Companion provides a unique masterclass in practical electronic design that draws on his considerable experience as a consultant and design engineer. As well as introducing key areas of design with insider's knowledge, Tim focuses on the art of designing circuits so that every production model will perform its specified function - and no other unwanted function - reliably over its lifetime.

The combination of design alchemy and awareness of commercial and manufacturing factors makes this an essential companion for the professional electronics designer. Topics covered include analog and digital circuits, component types, power supplies and printed circuit board design.

The second edition includes new material on microcontrollers, surface mount processes, power semiconductors and interfaces, bringing this classic work up to date for a new generation of designers.

· A unique masterclass in the design of optimized, reliable electronic circuits
· Beyond the lab - a guide to electronic design for production, where cost-effective design is imperative
· Tips and know-how provide a whole education for the novice, with something to offer the most seasoned professional

What this circuit does is automatically press the Power Button on my Composite to VGA converter twice: Once when I change into reverse, and a second time when I go back into drive. This changes my LCD monitor over to the rear-view camera (Composite), and then back over to my CarPC (VGA) automatically.

The circuit is basically two very simple Resistor/Capacitor (RC) timers.
Each circuit works on the property that as the charge in a capacitor increases the DC resistance and current decreases.

This circuit is simple and the components don't have to be exact. It is cheap, simple to build, and doesn't require any regulators or integrated circuits.
I do not have values filled in, as I usually just experiment with values until I find some that work well.
But, the larger the capacitor the longer it takes to charge and the longer the pulse output. Since the switch on my VGA converter is momentary, only a brief pulse is needed. Somewhere in the neighborhood of 150uF capacitors, and 1K resistors. The drain resistors can be very small, 100ohms or so.

Circuit design: I choose not to use any complicated microprocessors or timers in the circuit for a few reasons: This circuit is super easy to build, has minimal parts that may fail, and doesn't require a PCB. The circuit is designed as two self-reseting timers. Each timer sends out a single pulse to activate the power switch on the VGA converter.

Initial Circuit operation:
When the circuit is first installed, +12v Battery charges up the C1 capacitor, though R1.
Once C1 charges up fully the current across it will drop to nearly zero and it will remain trickle charged by the car battery. Unless your capacitor is defective there is no risk of draining your car battery using this technique.

Normal operation:
When you change the car into reverse, power is sent to the Reverse lights on your car.
This voltage will do two things when it passes into the circuit: First, it will energize both relays. This will discharge circuit C1 through R3, effectively resetting this part of the circuit.

The second process is that C2 will begin to charge up through R2 and RLY2.

This will makes RLY3 close until C2 is fully charged. This effectively presses the button on the VGA converter, switching it over to the rear view camera signal. Once C2 is fully charged RLY3 will reset back to a open position.

When you switch from Reverse back into Drive, C1 will begin to charge up again. This trips RLY3 a second time, switching the convector back over to the VGA signal.

Once there is no longer power from +12v Reverse Lights: C2 will discharge though R4. This will reset this part of the circuit and things can start over the next time you switch into reverse.

Sorry for the overly detailed explanation but it may help some users.

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Currently my only problem is that my car briefly flashes the reverse lights when you move the shifter from Park through Reverse to Drive.
The VGA converter is not fast enough to switch on and off this quickly, so it often gets stuck in Reverse camera mode.

I am trying to figure out a good way around this.

English:
Fully integrated design flow ranges from initial system planning, to detailed circuit design, system level PCB design and panelization, followed by manufacturing documentation and outputs.

German:
Der vollstandig integrierte Design-Prozess der Losung CR-8000 reicht von der anfanglichen Systemplanung (System Planner) uber detailliertes Schaltungs-Design (Design Gateway) und Leiterplatten-Design auf Systemebene (Design Force) bis hin zur Nutzenerstellung sowie der Generierung fertigungsrelevanter Dokumente und Ausgaben (DFM Center).

French:
La suite integre pleinement l'ensemble du flux de la conception, allant de la planification du systeme initial (System Planer), jusqu'a la conception detaillee du circuit (Design Gateway), la conception des circuits imprimes au niveau systeme (Design Force) ainsi que la panelisation et la creation de la documentation et des donnees de fabrication (DFM Center).

Italian:
Il processo di progettazione completamente integrato della suite di prodotti CR-8000 spazia dalla pianificazione iniziale del sistema (System Planner), fino allo sviluppo del circuito dettagliato (Design Gateway), al disegno PCB a livello di sistema (Design Force), alla pannellizzazione e alla creazione di documentazione e formati di produzione (DFM Center).

The Newnes Know It All Series takes the best of what our authors have written to create hard-working desk references that will be an engineer's first port of call for key information, design techniques and rules of thumb. Guaranteed not to gather dust on a shelf!

Contents:
Chapter 1 The Fundamentals
Chapter 2 The Semiconductor diode
Chapter 3 Understanding diodes and their problems
Chapter 4 Bipolar transistors
Chapter 5 Field effect transistors
Chapter 6 Identifying and avoiding transistor problems
Chapter 7 Fundamentals
Chapter 8 Number Systems
Chapter 9 Binary Data Manipulation
Chapter 10 Combinational Logic Design
Chapter 11 Sequential Logic Design
Chapter 12 Memory
Chapter 13 Selecting a design route
Chapter 14 Designing with logic ICs
Chapter 15 Interfacing
Chapter 16 DSP and digital filters
Chapter 17 Dealing with high speed logic
Chapter 18 Bridging the Gap Between Analog and Digital
Chapter 19 Op Amps
Chapter 20 Converters-Analog Meets Digital
Chapter 21 Sensors
Chapter 22 Active filters
Chapter 23 Radio-Frequency (RF) Circuits
Chapter 24 Signal Sources
Chapter 25 EDA Design Tools for Analog and RF
Chapter 26 Useful Circuits
Chapter 27 Programmable Logic to ASICs
Chapter 28 Complex Programmable Logic Devices (CPLDs)
Chapter 29 Field Programmable Gate Arrays (FPGAs)
Chapter 30 Design Automation and Testing for FPGAs
Chapter 31 Integrating processors onto FPGAs
Chapter 32 Implementing digital filters in VHDL
Chapter 33 Overview
Chapter 34 Microcontroller Toolbox
Chapter 35 Overview
Chapter 36 Specifications
Chapter 37 Off the shelf versus roll your own
Chapter 38 Input and output parameters
Chapter 39 Batteries
Chapter 40 Layout and Grounding for Analog and Digital Circuits
Chapter 41 Safety
Chapter 42 Design for Production
Chapter 43 Testability
Chapter 44 Reliability
Chapter 45 Thermal Management
Appendix A Standards

. A 360-degree view from our best-selling authors
. Hot topics covered
. The ultimate hard-working desk reference; all the essential information, techniques and tricks of the trade in one volume

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