|
Circuit Forms Peak/Clipping Indicator - 11/22/01 EDN-Design Ideas: The simple peak
detector in Figure 1 is the result of a need for a single-5V-supply, level/clipping
indicator for a multimedia-PC sound system. The design is unique in that it detects
both stereo channels on a single peak-hold capacitor. All the adjustments in the
circuit simultaneously apply to both left and right stereo inputs.....(design idea
added 1/05) |
|
Circuit indicates ac mains fuse failure - 01/08/09 EDN-Design Ideas: , Use
this circuit to alert you when a fuse fails.....(design idea added 08/09) |
|
Contactless Mains Voltage Indicator - (circuit / schematic design added 11/06) |
|
Cut Phone Line Detector (Aaron Cake) - Can be used to alarm security system (added
2/03) |
|
Cut Phone Line Detector (Tony van Roon) - (schematic / circuit added 10/02) |
|
CW Zero Beat Indicator - (electronic Circuit / Schematic added 7/03) |
|
CW Zero Indicator - (electronic circuit added 7/03) |
|
Data Multiplexer Adds Cursor to LED Display Driver - 03/30/95 EDN-Design Ideas:
(design idea added 03/03/03) |
|
DC Current Indicator #4 - The circuit below uses some common components to turn on
an LED whenever DC current above a certain level is detected. The circuit uses a
very popular LM393 dual voltage comparator from National Semiconductor and a common
1N4148 signal diode. The diode acts as a crude 0.7v voltage reference.
Only one of the comparators inside the 8 pin package is used. A pair of
resistors across the diode forms a voltage divider, which produce a reference voltage
of about 0.015v. .... ….(designed by David A. Johnson) |
|
DC Current Indicator 6 - The circuit below is a simple way to indicate when DC
current is flowing through a wire. The circuit is designed so it will turn on a
LED indicator light, whenever the voltage drop across a shunt resistor exceeds about
0.1 volts. The value of the resistor can be selected based on the desired
current flow. Although I show a circuit for 12v operation, the circuit can be used
over a wide range from 3v to perhaps 24v.... ….(designed by David A. Johnson) |
|
Digital Mains Voltage Indicator - (electronic Circuit / Schematic added 10/04) |
|
Doorbell for the Deaf (Andy Collinson) - This circuit provides a delayed visual
indication when a door bell switch is pressed. In addition, a DPDT switch can be moved
from within the house which will light a lamp in the door bell switch. The lamp can
illuminate the words "Please Wait" for anyone with walking difficulties.....(schematic
/ circuit design added 9/02) |
|
Doorbell Indicator-Remote - (electronic design added 6/07) |
|
Electrical Current Indicator - I designed this circuit as a simple current
indicator for any load ranging from 40 watts to 250 watts. The circuit turns on
a small LED, whenever it detects current flowing to a remote load. ….(designed by
David A. Johnson) |
|
Expanded scale indicator revisited - 08/08/02 EDN-Design Ideas: The visualization
aid that a previous Design Idea describes allows only the expansion of the upper end
of the scale (Reference 1). But what can you do if, according to your project
requirements, you need to expa.....(design idea added 1/05) |
|
Fastest Finger First Indicator - (electronic Circuit / Schematic added 10/04) |
|
Flashing LED Power Indicator Draws Low Current - This circuit flashes a power
indicator LED to keep the average current low. ….(designed by David A. Johnson) |
|
Free Line Indicator Stops Interruptions - 12/07/00 EDN-Design Ideas: / When only
one phone line is available for two phones, each time you want to make a call, someone
may be using the second phone. A simple circuit lights an LED, which indicates whether
the line is free (Figure 1a). Batteries are unnecessary; the phone line powers the
circuit, and an accumulator saves energy for an "in use" indication.....(design idea
added 11/05) |
|
Free-line indicator stops interruptions - 12/07/00 EDN-Design Ideas: PDF contains
multiple circuits, scroll to find this circuit….When only one phone line is available
for two phones, each time you want to make a call, someone may be using the second
phone. A simple circuit lights an LED, which indicates whether the line is free
(Figure 1a). Batteries are unnecessary; the phone line powers the circuit,.....(design
idea added 4/02) |
|
Fuse Monitor/Alarm - a simple way to see if a fuse has blown without removing it
from its holder (added 4/02) |
