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Digital  / Logic Circuits 
Digital Circuits:   #'s - C       D - G       H - M       N - R       S - T       U - Z

Last Updated on: Monday, December 25, 2017 01:50 PM

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

"433" Revisited -  We touched on 433-434MHz wireless data back in the July 2003 Picaxe article but here's an updated workout focusing on the dirt cheap "get you started" modules now around.__ SiliconChip

"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

ÁC Acts as Dedicated Motor-control -  09/11/98 EDN-Design Ideas -  (Scroll to find this circuit design)   Motion-control systems often use a PWM signal to control the duty cycle for a motor driver or amplifier module.  Typical designs generate the PWM signals using ÁC with dedicated PWM output lines, such as the PIC16C65  (Microchip Technology, www.  microchip.  com) and the HC11  (Motorola Inc, www.  motorola.  com) .  However, these ÁC may have more features than necessary for a motion-control system with multiple degrees of freedom.   __ Circuit Design by Dylan Horvath, Gecko Sysytems Inc, Austin, TX

ÁC 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 __ Circuit Design by Yongping Xia, Teldata Inc, Los Angeles, CA

ÁC 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 __ Circuit Design by Carlos Cossio, Santander, Spain

ÁC 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 __ Circuit Design by Thomas Schmidt, Microchip Technology, Chandler, AZ

ÁC 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 __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

ÁC 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 ÁC, such as  68HC705KJ1 and 68HC7051A   (Motorola] __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

ÁC 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 __ Circuit Design by William Grill, Riverhead Systems, Littleton, CO

ÁC 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 ÁCs.  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 __ Circuit Design by Jorge Luis B Romeu, IdeaWorks LTD, Syracuse, NY

ÁC 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 ÁC, the time period of the measured frequency must be relatively close to the internal clock of the ÁC.  For example, if the internal clock period is 1 sec, then.   __ Circuit Design by Stan D'Souza, Microchip Technology Inc, Chandler, AZ

ÁC multiplexes six digital potentiometers -  05/11/00 EDN-Design Ideas In Figure 1's circuit, a ÁC 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.   __ Circuit Design by Ted Salazar, Maxim Integrated Products, Sunnyvale, CA

ÁC 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.    __ Circuit Design by Luke Barker, Reinke Mfg Co, Deshler, NE

ÁC 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 __ Circuit Design by Lloyd Khuc, Motorola Inc, Austin, TX

ÁC 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 ÁC 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) .   __ Circuit Design by Lukasz Sliwczynski, University of Mining and Metallurgy, Institute of Electronics, Cracow, Poland

ÁC 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 __ Circuit Design by Mika Maaspuro, Kirstinmaki, Espoo, Finland

ÁC 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.    __ Circuit Design by Yongping Xia, Philips Lighting Electronics Co, Torrance, CA

ÁC 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 ôBig Boxö programmeŚbundled offerings that provide tool chains from a number of third-party suppliers.  The tool set targets a number of ôtypicalö application areas.  The company integrates the tools through a standard interface and includes training and support from the toolsĺ manufacturers.  Part of Siemensĺ ôSpaceö programme, the Big Box covers 8-, 16-, and 32-bit microcontrollers Page includes several designs.   __ Circuit Design by Graham Prophet

ÁC 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 signalĺs phase changes from 0 to 360� with shaft rotation.  The signal amplitude __ Circuit Design by Lev Freidin, Patriot Sensors & Controls Corp, Simi Valley, CA

ÁC-based one-shot has wide range -  06/19/97 EDN-Design Ideas The ÁC-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 ÁC.  The PIC16C54 is a low-cost, high-speed, __ Circuit Design by Yongping Xia, International Teldata Corp, Los Angeles, CA

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

1 microcontroller serves multiple external interrupts -  02/01/01 EDN-Design Ideas In designing ÁC-based systems, you often face a situation in which the ÁC 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 __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

1 switch controls digital potentiometer -  09/19/02  EDN-Design Ideas This design idea     is an evolution and simplification of another    (Figure 1, Reference 1].  Replacing the three inverted-input NOR gates with their logical equivalents, positive-input NAND gates, makes these three gate symbols consistent __ Circuit Design by Jim Bach, Delphi Delco Electronics Systems, Kokomo, IN

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 MonatMesa 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

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

12 Volt Generation -  PIC Project  The PWM output available from many PIC chips can be used to generate 12 volts.  This is very useful in making programmers for PICs that run on +5 volts only.   __ Designed by Luhan MonatMesa Arizona

12/24V AuxiliaryBattery Controller -  Going bush in the 4WD or camper? Want to add a second battery for security and safety? Here's the safe way to do it.__ SiliconChip

12/24V MPPT Solar Charge Controller Rev.1 -  Mix-It: An Easy-To Build 4-Channel Mixer__ SiliconChip

120 VAC Lamp Dimmer -  The full wave phase control circuit below was found in a RCA power circuits book from 1969.  The load is placed in series with the AC line and the four diodes provide a full wave rectified voltage to the anode of a SCR.  Two small signal transistors are connected in a switch configuration so that when the voltage on the 2.2uF __ Designed by Bill Bowden

12V 100W Converter with Adjustable 15-35V DC Output -  Did you build the 12/24V 3-stage MPPT solar charge controller published in the February 2011 issue? Then you will probably want this companion 12V 100W inverter as well.  It will power laptops and other devices which require a DC voltage between 15V & 35V.__ SiliconChip

12V Digital Timer using 240v Timer Module -  240V timers are very cheap these days.12V timers are not so cheap.  So why not use the "innards" out of a 240V timer and make a very flexible 12V timer?__ SiliconChip

15-step digital power supply -  Here is a simple circuit to obtain variable DC voltage from 1.25V to 15.19V in reasonably small steps as shown in the table.  The input voltage may lie anywhere between 20V

16 Bit PC Serial Port Receiver CMO - S -  This circuit was designed to control a 32 channel Christmas light  show from the PC serial port.  Originally designed with TTL logic,  it has been simplified using CMOS circuits to reduce component  count.  It is a fairly simple, reliable circuit that requires only  4 common CMOS chips    (for 8 outputs) , an optical isolator, and a  few discrete components. __ Designed by Bill Bowden

16-bit adjustable reference uses 8-bit digital potentiometers -  12/25/03 EDN-Design Ideas It may be easy to find a precision voltage reference for your application; however, a programmable precision reference is another matter.  The circuit in Figure 1 yields a precision reference with an LSB of 62.5 ÁV.  The circuit is a 16-bit DAC using three 8-bit digital potentiometers and three CMOS op amps __ Circuit Design by Bonnie Baker, Tucson, AZ

1-I/O line drives shift register with strobe -  03/28/13  EDN-Design Ideas This Design Idea shows how a single microcontroller port can drive a lot of output lines through shift register. by Zoran Mijanovic & Nedjeljko Lekic


insert i-digital bottom when top is fixed

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