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• CIRCUIT FORMS DIVIDE BY 1.5 COUNTER
  Two inexpensive ICs divide a TTL clock signal by 1.5. By following the circuit with another flip/flop, you could also generate a divide by three function.

• DARKROOM CAMERA SHUTTER TIMER
  This circuit was designed to control a film exposure shutter for a darkroom. It has 8 time steps ranging from 0.35 seconds to 4 seconds. It is activated by a foot switch and draws power from an external 12 volt DC supply.

Defining & Testing Dynamic Parameters in High Speed ADCs, Part 1:  Maxim Application Notes / 728 / May-05  (app note added 6/06)

Delay Simulator Debugs Communications Equipment:  10/27/94 EDN-Design Ideas / (added 3/03)  Phone calls over satellite circuits experience a ¼-sec transmission delay in each direction. The low-cost circuit (around $20) in Fig 1a simulates this delay and provides hooks for inserting noise, echo, and other impairments. Designers debugging modems, fax machines, and other communication equipment can use this circuit to troubleshoot handshake timing and connection problems caused by transmission delays.

Delta Sigma ADC Bridge Measurement Techniques:  AN96 - Linear Technology - AN96 features several applications that demonstrate how to take full advantage of Linear Technology's delta sigma ADCs when interfacing to sensors. In many cases, signal conditioning can be greatly simplified or eliminated completely. This note explains where it is appropriate to use amplifiers and how to optimize amplifier gain. Also included are discussions on measuring effective number of bits (ENOB) and the relationship to instrument performance, frequency response of delta sigma ADCs, and test techniques. C source code for all of the applications is included to aid firmware development.

Design makes handy audible circuit tracer:  01/09/03  EDN-Design Ideas / (added 10/03) The circuit tracer in Figure 1 is a handy tool for finding connectivity paths on a pc board. Because the sense voltage you use to measure the path is lower than a transistor's VBE voltage, you can use the design in circuits containing semiconductor elements without affecting the measurement. The tracer's output takes the form of audio tones

Designer's Guide to Flash-ADC Testing, Part 1:  AN-215A - Analog Devices Application Notes  (app note added 6/06)  Flash ADCs Provide the Basis for High Speed Conversion.

Designer's Guide to Flash-ADC Testing, Part 2:  AN-215B - Analog Devices Application Notes  (app note added 6/06)  DSP Test Techniques Keep Flash ADCs In Check

Designers's Guide to Flash-ADC Testing, Part 3:  AN-215C - Analog Devices Application Notes  (app note added 6/06)  Measure Flash-ADC Performance for Trouble-Free Operation

Designing and Characterizing TRL Fixture Calibration Standards For Device Modeling (11/20/01) :  Application Note - California Eastern Laboratories - Doc #954  (app note added 6/06)

Designing and Testing 3GPP W-CDMA User Equipment:  Aligent Application Note  (added 2/06)

Designing and Testing cdma2000 Base Stations:  Aligent Application Note  (added 2/06)

Designing Energy Meters with the PIC16F873A:  Microchip Application Note - Published 12-Sep-05   (app note added 6/06)

Designing RF Probe:  make your self simple and highly useful RF probe. An essential tool for every home brewer. . (added 9/04)

Detecting Keys using a Timer:  Toshiba 870X Series Application Note  (app note added 2/06)

Detecting Keys using an A/D Converter:  Toshiba 870X Series Application Note  (app note added 2/06)

Dew sensor:  (electronic circuit added 10/05)

DIGITAL LED AMMETER:  Measures current up to 10A with selected 100mA, 10mA and 1mA resolutions.  (circuit added 8/06)

DIGITAL LED VOLTMETER:  Measures voltages up to 199.9V with 0.1V resolution.  (circuit added 8/06)

Digital PC Oscilloscope:  (circuit / schematic added 2/03)

Digital Volt Meter with Video Output:  (electronic circuit added 09/05)

Digital Volume Control:  based on DS1669 Digital Pot IC (added 5/02)

Digital/Standard Phone Line Tester:  make sure that the line is suitable for modem use and your PCMCIA does not damage if you plug it in (added 5/02)

Digitally Programmable resistor serves as test load:  03/03/05 EDN Design Ideas  / (added 5/05)  Figure 1 illustrates a digitally programmable precision resistance that can serve as a microprocessor-driven power-supply load in custom-designed ATE (automatic-test equipment). An 8-bit current-output DAC, IC1, a DAC08, drives current-to-voltage converter IC2A, which in turn drives the gate of power MOSFET Q1.

Dip Oscillator for HF:  (electronic design / schematic added 2/05)

Distortion Analyzer:  (electronic (schematic / circuit added 4/02)

DMM Measures Light Level #1:  08/15/96 EDN-Design Ideas  / (added 3/03)

DP83815 MacPHYTER and DP83816 MacPHYTER-II High Data Rate Stress Testing:  National Semiconductor - Application Note   (app note added 2/06)

DTMF Receiver IC MT8870 Tester:  (circuit / schematic design added 6/06)

Dynamic load circuit determines a battery's internal resistance:  03/31/05 EDN Design Ideas  / (added 5/05)  Meet the challenge of measuring a battery's internal parameters with a nonstatic load approach.

Dynamic Testing of High Speed ADCs, Part 2:  Maxim Application Notes / 729 / Feb-06  (app note added 6/06)

E-B-C Transistor Pin Identifier:  Tests transistors and diodes for polarity - Simple circuitry - 9V Battery operation (added 02/05)

Electromagnetic Emissions Test Report on Solid State Energy Meter:  Electro - Analog Devices Application Notes  (app note added 6/06)  This report describes electromagnetic immunity testing performed on September 9, 1999 through September 10, 1999 on the Solid State Energy Meter. Testing was performed pursuant to IEC 1036:1996, a standard for alternating static watt-hour meters for active energy.

Electromagnetic Emissions Test Report on the AD7755:  AD7755 - Analog Devices Application Notes  (app note added 6/06)  This document describes electromagnetic emissions testing performed on the Energy Meter (AD7755)   on September 8, 1999, pursuant to EN55022 requirements. It may be used to demonstrate compliance with the European Union emissions requirements pursuant to the EMC directive

Electromagnetic Field Detector #2:  This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that surrounds a transformer is heard as a50 or 60Hz buzz.   (added 5/02)

Electromagnetic field detector #3:  This lovely circuit is a real gem! Easy to assemble and more sensitive than many commercial devices available. It's based around an LF351 low-noise operational amplifier and a 1mF choke acting as the sensor. Unlike most other simple EMF detectors, this one has a meter output for accurate reading, but alternatively, you can also roughly estimate the frequency of the field by plugging in headphones. It can detect any field from 50Hz to 100kHz, making it highly versatile and a worthwhile addition to any hobbyist's workbench. (added 10/05)

Electromagnetic field detector:  (electronic design added 10/06)