"Do Not Disturb" Telephone Timer - It takes your phone off the hook and automatically hangs up again after a preset time.  A LED indicates when the phone is off the hook.__ SiliconChip

"Whistle & Point " Cable Tracer - Connect it to one end of the cable conductor and listen for the whistle at the other end and your wiring tracing problems are solved.__ SiliconChip

µC Based Performs Frequency Multiplication - 27-May-99 EDN-Design Ideas - The traditional frequency multiplier requires many elements  a phase comparator to detect the phase error between the input and the output signals, a lowpass filter to convert the phase error Design by Yongping Xia, Teldata Inc, Los Angeles, CA

µC controls charge pump as background task - 08/01/97 EDN-Design Ideas - Because of power consumption and cost, designers of battery-powered devices mainly choose components that run at 3V or lower.  Unfortunately, many devices operate only at 5V, including LCDs with built-in drivers, programming lines of many EEPROMs and flash chips, and CMOS ADCs Design by Carlos Cossio, Santander, Spain

µC Controls Digital Potentiometer - 10/08/98 EDN-Design Ideas - Many digitally controlled potentiometers    (for example, the LM1971/02/3 from National Semiconductor, www.national.com] incorporate a three-wire serial digital interface, using data, clock, and enable lines.  In Figure 1, the potentiometer's nomenclature for these lines is Data-In.  Several circuits in article, scroll to find this one.      Design by Lukasz Sliwczynski, University Of Mining And Metallurgy, Krakow, Poland

µC Detects transmission rate of RS-232 interface - 09/30/99 EDN-Design Ideas - RS-232 is the most common serial interface in the PC world.  Most RS-232 interfaces communicate with the receiver at a fixed transmission rate, such as 9600 baud.  But what happens if the transmitter operates with different transmission rates? Different transmission rates Design by Thomas Schmidt, Microchip Technology, Chandler, AZ

µC forms FM oscillator - 10/28/99 EDN-Design Ideas - A project required an inexpensive oscillator whose frequency increased step by step from 200 to 400 Hz and then decreased to 200 Hz.  The first step was to design a VCO with a staircase driver.  However, this approach entailed at least four ICs and many discrete components.  An Design by Abel Raynus, Armatron International, Melrose, MA

µC generates a frequency burst - 02/03/00 EDN-Design Ideas - Pulse-sonar applications require generating bursts of a given frequency, duration, and repetition rate.  Traditionally,  burst generator comprises a crystal oscillator with pulse modulation.  But  easiest and cheapest way to generate  bursts is by using an inexpensive 8-bit µC, such as  68HC705KJ1 and 68HC7051A   (Motorola] Design by Abel Raynus, Armatron International, Melrose, MA

µC implements Pushbutton Light Dimmers - 06/18/98 EDN-Design Ideas - A project required building a synchronous-demodulator circuit to track a line drawn on paper.  beauty of  synchronous-modulator/demodulator approach is its inherent noise rejection.  File contains several circuits, scroll to find this one Design by William Grill, Riverhead Systems, Littleton, CO

µC makes inexpensive sine-wave generator - 12/17/98 EDN-Design Ideas - You can use A/D converters or external, controllable oscillators to generate sine waves from low-power, low-cost µCs.  However, these methods add cost, reduce reliability, increase circuit and software complexity, increase power consumption, and increase overall size.  Alternatively Page includes several designs.  Scroll to find this one Design by Jorge Luis B Romeu, IdeaWorks LTD, Syracuse, NY

µC measures High-frequency signals - 03/02/98 EDN-Design Ideas -    (File contains many circuits, please scroll to find this one)  To measure a high-frequency signal using an 8-bit µC, the time period of the measured frequency must be relatively close to the internal clock of the µC.  For example, if the internal clock period is 1 sec, then.   Design by Stan D'Souza, Microchip Technology Inc, Chandler, AZ

µC multiplexes six digital potentiometers - 05/11/00 EDN-Design Ideas - In Figure 1's circuit, a µC lets you adjust as many as six digital potentiometers.  Like mechanical potentiometers, digital potentiometers can adjust regulator outputs or speaker volumes and act as rheostats.  Available in resistances of 50, 100, and 200 kV, they let you throw away your mechanical potentiometers and the little flat-headed screwdrivers that go with them.   Design by Ted Salazar, Maxim Integrated Products, Sunnyvale, CA

µC provides analog data to PLC chip - 07/03/97 EDN-Design Ideas - The low price of programmable-logic controllers   (PLCs] makes these small devices a good choice for many system designs.  Most of the controllers, however, accommodate only digital inputs.  One such.    Design by Luke Barker, Reinke Mfg Co, Deshler, NE

µC provides three-key, five-sequence lock function - 12/03/98 EDN-Design Ideas -    (File has several circuits, scroll to this one)  Using MicroChip's 12-C508 eight-pin �C, you can inexpensively implement a digital-sequence lock with debounce and status-indicator features   (Figure 1) .  The design exploits the internal-oscillator, watchdog-timer, and wake-up-on-pin-change features inherent in the �C, and it provIdeas an application that supports key acknowledge and out-of-sequence error detection.  The circuit Using MicroChip's 12-C508 eight-pin �C, you can inexpensively implement a digital-sequence lock with debounce and status-indicator features   (Figure 1) .  The design exploits the internal-oscillator, watchdog-timer, and wake-up-on-pin-change features inherent in the �C, and it provIdeas an application that supports key acknowledge and out-of-sequence error detection.  The circuit .    Design by William Grill, Riverhead Systems, Littleton, CO William Grill, Riverhead Systems, Littleton, CO

µC Provides Wireless Keypad Control - 10/08/98 EDN-Design Ideas -    (File contain several circuits.  Scroll to find this one)  Portable systems, such as telephone handsets, make extensive use of low-dropout   (LDO]regulators.  se components provide noise-sensitive parts with a stable power-supply line Design by Lloyd Khuc, Motorola Inc, Austin, TX

µC reprograms audio DAC via serial interface - EDN-Design Ideas - 01/07/1999   NOTE :  Mulitple Ideas, Scroll to find this one.  You can use a simple µC to continuously program an audio DAC so that it operates in a 20-bit resolution mode    (Figure 1) .  After power-on, the PCM1710 delta-sigma DAC    (Burr-Brown Corp, www.burr-brown.com) operates in its default 16-bit resolution mode.  Switching to its 20-bit resolution mode requires supplying the converter with a control word using its three-wire serial digital interface    (SDI) .   Design by Lukasz Sliwczynski, University of Mining and Metallurgy, Institute of Electronics, Cracow, Poland

µC Routines Clear Up Errors - 11/10/94 EDN-Design Ideas - The ZIPfile attached to EDN BBS /DI_SIG #1619 contains executable programs and source code for programs that allow you to program MC68HC11 microcontrollers via an RS-232C connection to your PC.  The programs replace obsolete, error-laden programs published in an applications note Design by Mika Maaspuro, Kirstinmaki, Espoo, Finland

µC squares input signal - 12/19/96 EDN-Design Ideas - Converting a random-width pulse to a signal with the same frequency but with a 50% duty cycle isn't easy, especially when the specified frequency range is large.    Design by Yongping Xia, Philips Lighting Electronics Co, Torrance, CA

µC tool packages focus on specific applications. - 04/01/99 EDN-Design Ideas -    (Scroll to find this one)  Siemens has extended its microcontroller-development tool support with the “Big Box” programme—bundled offerings that provide tool chains from a number of third-party suppliers.  The tool set targets a number of “typical” application areas.  The company integrates the tools through a standard interface and includes training and support from the tools’ manufacturers.  Part of Siemens’ “Space” programme, the Big Box covers 8-, 16-, and 32-bit microcontrollers Page includes several designs.   Design by Graham Prophet

µC uses Simple Circuit tool for angle measurement - 04/10/97 EDN-Design Ideas - The circuit in Figure 1 uses a 2V, 2250-Hz resolver as an angle sensor.  The excitation for the resolver is irregular, using two 90�-phase-shifted, 900-Hz signals.      (The stator is the primary winding.   ] The output signal’s phase changes from 0 to 360� with shaft rotation.  The signal amplitude Design by Lev Freidin, Patriot Sensors & Controls Corp, Simi Valley, CA

µC-based one-shot has wide range - 06/19/97 EDN-Design Ideas - The µC-based, digitally programmable, monostable multivibrator in Figure 1 has more accurate timing than a conventional RC-based device because a 20-MHz crystal controls the µC.  The PIC16C54 is a low-cost, high-speed, Design by Yongping Xia, International Teldata Corp, Los Angeles, CA

µP Displays 10 Bit Data on Three LEDs - 11/07/96 EDN-Design Ideas - circuit in Figure 1 uses a PIC16C55 µP to read 10-bit binary data and directly display  data in decimal format on three common-cathode LED displays.  If value of  data exceeds 999,  displays show three hyphens   (---) to represent overflow.  PIC16C55 has high drive Design by Yongping Xia, Philips Lighting Electronics, Torrance, CA

µP Socket Automatically Senses Upgrade - 03/03/94 EDN-Design Ideas - The circuit in Fig 1  automatically senses when a user upgrades a Motorola 68040 µP system with a 68060 µP, changing the µP's supply voltage from 5 to 3.3V.  This automatic voltage change is far safer than any manual scheme could be, and this technique lets you easily adapt the circuit to other applications that must switch between 5 and 3.3V Design by Thomas Mosteller, Linear Technology Corp, Lansdale, PA

0-5V PIC Voltmeter - Higher voltage can be measured with resistor voltage divider 

1 Microcontroller Pin Drives Two LEDs with Low Quiescent Current - 02/07/08  EDN-Design Ideas - Two simple circuits allow a battery-powered microcontroller to drive two LEDs Design by Antonio Muńoz, Laboratorios Avanzados de Investigación del I3A, Zaragoza, Spain, and Arturo Mediano, PhD, GEPM University of Zaragoza, Zaragoza, Spain

1 microcontroller serves multiple external interrupts - 02/01/01 EDN-Design Ideas - In designing µC-based systems, you often face a situation in which the µC has to respond to an external event happening at an uncertain moment in time.  One example is receiving an echo from an object in a pulse-range measuring sy Design by Abel Raynus, Armatron International, Melrose, MA

1 processor pin controls on/off function - 04/29/04  EDN-Design Ideas - A recent Design Ideas - prompted me to offer the simpler solution that I used in a recent project    (Reference 1].  We needed a momentary power switch with processor supervision.  This supervision would allow the processor to delay a powe Design by Michael Sirkis, Radio Systems, Logan Township, NJ

1 wire connects microcontrollers - 10/22/98 EDN-Design Ideas -    (File has several circuits, scroll to find this one)  Low-cost µCs, such as Motorola's 68HC705 Series, offer great simplicity at the expense of some useful functions—notably, serial data transmission.  Unlike their predecessors, these µCs do not have serial communication interfaces    (SCIs) , serial peripheral interfaces    (SPIs) , or simple serial I/O ports    (SIOPs) .  This method describes how you can overcome this deficiency by creating an asynchronous serial interface through µC software Design by Abel Raynus, Armitron International, Melrose, MA

1.5kW Induction Motor Speed Controller, Pt.1 - You've asked for it many times and we have always said NO! It's too complex, too difficult, too expensive, whatever.  Now we're saying YES.  This Induction Motor Speed Controller is suitable for motors up to 1.5kW    (2HP) and can be used to control speed over a wide range.  It will save big dollars with swimming pool pumps and will be great for running machinery at different speeds.  Even better, it will control 3-phase motors as well!__ SiliconChip

10 Pulse Coding - PIC Project  Ten-pulse coding was developed to save power, increase range, and be very speed tolerant.  It consists of ten pulses with nine timed gaps between them.  The first gap is the reference time.  The eight remaining gaps are either longer    (one) or shorter    (zero) than the reference.   __ Designed by Luhan Monat - Mesa Arizona

10 Tricks for Interfacing to the PIC16c508 - Most of the ideas in this chapter can be found on the pages of this website, but just in case you want to go over the capabilities of the '508A, we have brought them together.  Quite often when you are programming, the first thing you will run out of is output lines.  Many projects need lots of drive lines and if you need more than about 8, you should go to another micro-controller.  Don't expect an 8-pin chip to perform the impossible.   __ Designed by Prepared Colin Mitchell

1000:1 EHT Probe - Do you need to measure the EHT voltage in a CRT-based scope, computer monitor or TV receiver, or perhaps in a photocopier, laser printer or microwave oven? You'll need an EHT probe to suit your digital multimeter    (DMM) to do this and you'll find they are pretty pricey.  Not to worry though, because here's one you can build for less than $40.__ SiliconChip

100W RMS/Channel Stereo Amplifier-Part 3 - Final article covers the assembly of the remaining modules and includes the full wiring and setting up details.__ SiliconChip

101 AT Keyboard to ASCII Decoder using 68HC705J1A MCU - Why would you want to interface the Keyboard? The IBM keyboard can be a cheap alternative to a keyboard on a Microprocessor development system.  Or maybe you want a remote terminal, just couple it with a LCD Module.  Maybe you have a RS-232 Barcode Scanner or other input devices, which you want to use with existing software which only allows you to key in numbers or letters.  You could design yourself a little box to convert RS-232 into a Keyboard Transmission, making it transparent to the software __ Designed by Craig Peacock

10A DCC Booster for Model Railways - Most DCC base stations have puny current capabilities which are exposed if you want to run more than a few locos and peripherals on your model railway layout.  Problem is, DCC boosters are expensive, with a well-known 5A booster costing over $200.  Problem no longer; build this 10A beauty at a fraction of the cost.__ SiliconChip