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• Isolated Power Supply for Digital Panel Meters -- September 13, 2008
  Many inexpensive digital panel meters, such as the one shown below, are designed to operate from a 9v battery.  However, the nature of the panel meter internal design often requires that the DC supply used to power the device be isolated from the ground terminal of the panel meter’s input.  This often makes it difficult to use with a common connection between a DC power supply ground and a sensor’s circuit ground.  But, you can generate this floating voltage fairly easily using the simple circuit below.

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......

General Purpose Display Controller - This is a general purpose display controller for small microcontrollers. It will be used for various use because it is easy to change its configuration through using a CPLD.  (added 6/06)

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

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

Handheld/Portable Display LCD/OLED - Intersil Application Block Diagram  (app note added 6/06)

H-Bridge - drives DC motors forward and backward. (added 7/03)

High Power Ccfl Backlight Inverter for Desktop LCD Displays - DN164  Design Notes (Linear Technology) (app note added 2/06)

High Power Desktop LCD Backlight Controller Supports Wide Dimming Ratios While Maximizing Lamp Lifetime - DN264  Design Notes (Linear Technology) (app note added 1/06)

High Side Driver has Fault Protection - 09/05/02 EDN Design Ideas  /  (added 1/05)  High-side drivers find common use in driving grounded solenoid coils and other loads. Short-circuit protection for such drivers is essential for avoiding damage from wiring faults and other causes. Polymer fuses are generally too slow, and discrete current-limiting circuits are large and cumbersome. The circuit in Figure 1 uses a small, low-dropout linear regulator as a high-side switch and p......

High Speed Low Skew RS422 Drivers and Receivers Solve Critical System Timing Problems - National Semiconductor Application Note 05 Oct1998 / (app note added 7/02)

Highside Driver Feeds IGBTs and MOSFETs - 11/23/00 EDN-Design Ideas / (added 5/03)

IC Forms Differential Line Driver/Receiver - 05/25/95 EDN-Design Ideas / (added 3/03) you can use the HFA1212 dual video buffer to implement differential line drivers and receivers with a minimum of external components

Illumination Circuitry for Liquid Crystal Displays - AN49 Linear Technology Current generation portable computers and instruments utilize backlit liquid crystal displays. The back light requires a highly efficient, high voltage AC source as well as other supply circuitry. AN49 details these circuits and also includes sections on efficiency....(app note added 2/06)

Improve Roll Off of Sallen Key Filter - 09/30/04 EDN Design Ideas  /  (added 10/05)The well-documented Sallen-Key active filter is a staple of analog design. This Design Idea shows a way to obtain better roll-off by adding just a few common passive components. Figure 1a shows a typical implementation of a three-pole, lowpass version. In operation, you adjust the ratio of capacitors C1 and C2 to give a peaked response for the two poles within the feedback loop....

Input Filter Prevents Instrumentation Amp RF Rectification Errors - 11/13/03 EDN Design Ideas  / (added 11/05)  Instrumentation amplifiers serve in a variety of applications that need to extract a weak differential signal from large common-mode noise or interference. However, designers often overlook the potential problem of RF rectification inside the instrumentation amplifier. The amplifier's common-mode rejection normally greatly reduces common-mode signals at an instrumentation amplifier's input.

Instrument panel lamp dimmer control Circuit - This circuit uses an MC3392 low side protected switch and an MC1455 timing circuit to form an automotive instrumentation panel lamp dimmer control. The brightness of incandescent lamps….(electronic design added 09/08)

Isolated Power Supply for Digital Panel Meters - Many inexpensive digital panel meters, such as the one shown below, are designed to operate from a 9v battery.  However, the nature of the panel meter internal design often requires that the DC supply used to power the device be isolated from the ground terminal of the panel meter’s input.  This often makes it difficult to use with a common connection between a DC power supply ground and a sensor’s circuit ground.  But, you can generate this floating voltage fairly easily using the simple circuit below. ….(designed by David A. Johnson)

Interface LCD with Ease - 04/27/00 EDN-Design Ideas / (added 1/06)

Interfacing 16x2 Character - LCD to parallel port / (added 7/02)

IRADK10 Motor Drive Reference Design Kit - The kit has a Graphical User Interface (GUI) that enables the user to control motor speed and set the basic control parameters such as PWM frequency and shut down conditions via the serial link. (added 3/05)