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Game Show Who's First
Indicator Lights: (circuit / schematic design added 6/06) |
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Garage Light Indicator LED: Garage Light Indicator LEDThis is the simplest possible way to power an LED off 115VAC. I
epoxied a high-brightness yellow LED into the switch plate to my garage light. The light switch is inside my house, but the garage light cannot be seen when the door is closed. This has caused
me to leave the garage light on overnight many times until I created this solution. I have outdoor lights that could use this solution as well (when I get around to it). This circuit was
soldered together, wrapped with electrical tape and tucked inside the electrical box containing the garage light switch. A small hole was drilled in the switch plate for the LED to stick out
of. Designed by Andrew
R. Morris (added 09/05) |
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Hot Water Tank Indicator: (schematic / circuit design added 9/02) |
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Indicator Features Expanded Scale: 02/21/02 EDN Design Ideas / (added 1/05) Test equipment for a
production line should be user-friendly (read "idiot-proof") and should offer minimal test time. In many cases, the test fixture must give an operator only one answer: pass or fail. Usually,
two indicators assume this role: green for pass and red for fail. In most applications, a sensor transforms the tested parameter to a voltage; the test fixture must measure this v... ... |
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Indicator has Electronic Lens: 09/04/03 EDN Design Ideas / (added 1/05) The method for implementing an
extended-scale meter described in an earlier Design Idea had a conceptual error: The meter impedance must change continuously, not discretely as expressed (Reference 1). You could achieve the
desired result by using a digital potentiometer controlled by an input voltage via an appropriate interface.... |
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Indicator LED Bus: This document describes the connection of the Indicator LED Bus to compatible displays and includes
example code for a BASIC Stamp and LCDC examples. (added 6/06) |
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Isolated indicator signals telephone line's status: 6/8/06 EDN Design Ideas / (added 11/06)
Micropowered circuit shows off-hook phone. |
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LED Battery Condition Indicator: (circuit / schematic design added 6/06) |
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LED Flasher Indicates Low Battery Condition: 01/02/97 EDN Design Ideas / (added 5/02) |
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Line busy indicator: This circuit flashes an LED if the phone line is in use
or is ringing. It is powered by the phone line, and it uses so little
current that several of them could be used on the same line without
interference. When first connected, let the circuit charge on an idle
line for a couple minutes before expecting it to work. A high-brightness LED
is recommended. (added 1/08) |
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Low Battery Indicator has High Efficiency: 05/03/01 EDN-Design Ideas / (added 11/05) |
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Low Battery Indicator uses Fleapower : 09/04/03 EDN-Design Ideas / (added 4/05) It is always desirable to use a
low-battery indicator that consumes as little power as possible. For a 9V, 450-mAhr alkaline battery, a 50-µA low-battery indicator can by itself run the battery down in a little more than a
year. Battery-powered devices that need to run continuously for a long time require battery indicators that consume minimal power.... |
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Message Waiting Flasher: This circuit starts flashing a neon light when the phone rings and continues flashing it until the
phone is picked up to remind you to check your voice-mail. The flashing neon light drives a voltage doubler (Q2) which keeps it flashing. Q1 ensures that the flashing is stopped when the phone
is picked up. Designed by
Andrew R. Morris
(added 6/06) |
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Model Aeroplane Navigation Strobe/Battery Level Indicator : Fair Waring, site contains annoying popups. If you are
interested in model aeroplanes and have the capital, a radio controlled electric park flyer is a must have. An RC aeroplane under 400 grams floats around like the rubber models of my
youth and contact with the ground doesn't seems to involve that sickening crunch that comes with larger models. Finding a deserted park in which to fly one (that propellor can still be
dangerous) and waiting for a windless day isn't always that easy but it sure beats driving an hour to a club field. Park flyers are definitely stress beaters and are also just plain fun.
(add 5/05) |
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Multi-Switch Doorbell with Indicators: (circuit / schematic design added 6/06) |
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Off Hook Phone Line Supplies 150 MW: 09/01/94 EDN-Design Ideas / (added 6/06) For systems that require 150 mW or less, the
power supply in Fig 1 draws power from ordinary phone jacks without interrupting the voice signal, thereby eliminating the need for batteries and ac adapters. Built into peripheral equipment
such as PCMCIA modem cards, this circuit can spare the battery in a host computer. The circuit is useful in portable systems that connect to subscriber (household) telephone lines, such as
modems and telephone test sets.... |
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Opamp Rectifier Signals Input State: 07)/21/94 EDN-Design Ideas / (added 3/03) The op-amp rectifier in Fig 1 operates from
a single supply and provides a logic output and an LED that indicate the state of the input voltage. The input-state indications are handy for calibration. Because the circuit operates from a
single supply, the 2.5V reference determines the level around which the circuit rectifies input waveforms.... |
