Constant Current Constant Voltage Converter Drives White LEDs:  09/02/04 EDN Design Ideas  / (added 11/05)  LEDs usually take their drive from a constant dc-current source to maintain constant luminescence. Most dc/dc converters, however, deliver a constant voltage by comparing a feedback voltage to an internal reference via an internal error amplifier. The easiest way to turn a simple dc/dc converter into a constant-current source is to use a sense resistor to convert the output current to a voltage...

Designing an LCD Dot Matrix Display Interface:  National Semiconductor Application Note   (app note added 2/06)

Designing High Current Chokes is Easy:  06/24/04 EDN Design Ideas  / (added 11/05)  Somewhat unusually, this Design Idea deals with a formula rather than a circuit. You might think that all the basic formulas of magnetic phenomena were discovered more than a century ago. In fact, they probably were, but, at the time, some were of little practical interest and were essentially disregarded and never included in books or formula tables.

Differential Driver Doubles as Versatile RF Switch Driver:  1/6/05   EDN-Design Ideas / (added 5/05)

Digital Call Sign Annunciator:  (electronic circuit added 4/05)

Digital Potentiometers Enable Programmable Biquadratic Filter:  07/22/04 EDN Design Ideas  / (added 11/05)  Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters. The biquadratic, or biquad, filter is an exception, however. You can change that filter's corner frequency (ω0), Q, and gain (H) by adjusting the values of three resistors. For that purpose, the lowpass biquad circuit of Figure 1 includes three digital potentiometers configure...

Driving LEDs in Battery Operated Applications: Controlling Brightness Power Efficiently:  Maxim App Note #1804 (app note added 02/05)

Dual-Display with LED Driver with 3/2x Switched Capacitor Boost:  National Semiconductor Application Note LM2796 February 2004 (app note added 02/05)

Easily Display Bit Map Images on Small Graphic Lcds:  11/19/98 EDN-Design Ideas / (added 3/03)  

Electronic Symbols Template:  (circuit added 9/04)

Embedded Processor Directly Drives Lcd:  01/09/03 EDN Design Ideas  /  (added 1/05)  Driving a bare LCD does not necessarily require specialized interface circuitry or peripherals. This Design Idea describes an alternative drive scheme, which you can easily implement using the general-purpose outputs of a microcontroller. Many embedded-system applications need to interact with a user by displaying simple numeric or alphanumeric characters....

Excel Offers Painless LCD Initialization:  09/20/01 EDN Design Ideas  /  (added 1/05)  To display a font or a symbol on an LCD, you need to convert the desired character into numerical data. Creating the data for an entire font set requires specialized tools; even with these tools, the task can be daunting. Alternatively, you can build a font calculator using an Excel spreadsheet. ...

Filtersfree Program Designs and Analyzes Passive and Active Filters:  02/05/2004  EDN-Design Ideas  In low-noise analog circuits, a high-gain amplifier serves at the input to increase the SNR. The input signal level determines the input-stage gain; low-level signals require the highest gain. It is also standard practice in low-noise analog-signal processing to make the circuit's bandwidth as narrow as possible to pass only the useful input-signal spectrum. (added 10/05)

Four Channel Digital Voltmeter with Display and Keyboard:  Microchip Application Note Published 27-May-05   (app note added 6/06)

Frequency Source Feeds Entire Lab:  01/23/03 EDN Design Ideas  /  (added 1/05)  Plumbing a laboratory with a standard frequency makes a lot of sense if the lab uses multiple frequency counters, spectrum analyzers, and other frequency-dependent test equipment. Rather than spending time keeping all of the instruments' oscillators in calibration or buying expensive, high-precision oscillators, you can use the circuit in Figure 1 to distribute a single calibrated frequency sou......

GPS LCD Display Project:  (electronic circuit added 7/03)

Graphic LCD Interface:  (electronic circuit added 7/03)