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LED Decibel Meter - The circuit below responds to sound pressure
levels from about 60 to 70 dB. The sound is picked up by an 8 ohm speaker,
amplified by a transistor stage and one LM324 op-amp section. You can also
use a dynamic microphone but I found the speaker was more sensitive. The
remaining 3 sections of the LM324 quad op-amp are used as.... |
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LED display Digital Voltmeter - This digital voltmeter is ideal to
use for measuring the output voltage of your DC power supply. It includes a
3.5-digit LED display with a negative voltage indicator. It measures DC
voltages from 0 to 199.9V with a resolution of 0.1V. The voltmeter is based
on single ICL7107 chip and may be fitted on a small 3cm x 7cm....(electronic
design added 6/07) |
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LED Oscilloscope - George Katz of Balgowlah Boys high in Sydney
presented a solid state oscilloscope. He says "probably the best advantage
is its very small size and the fact that it can run off the power supply of
the ….(electronic schematic added 11/08) |
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LED Oscilloscope 1 - Uses a matrix of 100 LED as a display (circuit added
8/06) |
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LED power meter - Used for testing RF transmitters.... |
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LED Tester - ….must register on this site.... [Published in Elecktor
July/August 2010] |
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LED Voltmeter - Measures voltages up to 199.9V with 0.1V resolution.
(circuit added 8/06) |
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LED Voltmeter Expanded Scale (ideal for your car) - Its Useful to see the
charge voltage. This Helps in detecting a Bad Alternator before it creates a dead
battery....(electronic schematic added 12/08) |
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LED VU Meter - The circuit is completely conventional, and is based on the
application notes from National Semiconductor. The circuit is shown in Figure 1 and as
you can see it uses a single IC and a few discrete components. The extra diode (D3) is
included to ensure that the DC to the LEDs is almost unfiltered.... |
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LEE Test Fixture Instructions - AN-60-021 Application Note MiniCircuits.com
(app note added 04/05/06) |
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LF Oscillator - A low frequency test oscillator for testing tone controls
and experimenting [Designer, Andy Collison] |
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Light Monitor 2 - The circuit below takes advantage of a low power op amp
with a “rail to rail” feature. The single resistor R1 defines the light
sensitivity of the circuit. The output voltage is directly proportional to the
intensity of light striking the small photodiode D1. In total darkness, the
output voltage will hover near zero volts. The capacitor C1 is chosen to filter
our most AC components of the light but by decreasing its value to just a few
picofarads, the circuit can operate in the tens of kilohertz range. A faster op
amp will be needed for higher speed signals. [Designed by David A. Johnson] |
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Light Pollution Meter - LED brightness control circuit and a millimeter to
compare light levels to LED level..... |
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Light Receiver works from 1kHz to over 70mhz - This circuit uses one tiny
C-MOS inverter IC to form a modulated light receiver with a very fast response. It is
designed around a PIN photo diode that is packaged for use with plastic optical
fibers. It can be used as an optical fiber receiver. By using the open end of the
optical fiber it can "sniff" out any modulated light signals.... [Designed by David A.
Johnson] |
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Light Sensor Adapter for Oscilloscope - (electronic schematic / circuit
added 4/02) |
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Lightening Detector - A VLF receiver tuned to 300 kHz designed to detect the
crackle of approaching lightning. A bright lamp flashes in synchrony with the
lightning bolts indicating the proximity and intensity of the storm. It has a superior
RF section with a single resonance near 300kHz and plenty of sensitivity. The antenna
is a telescopic antenna that extends to two or three feet(added 10/04) [Circuit
designed by Charles Wenzel] |
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Lightning Activated Camera Shutter Trigger - This circuit is used to trigger
a camera's electronic shutter circuit when a flash of lightning is present. This
circuit would also work for photographing fireworks displays or other events involving
flashes of light…. [G. Forrest Cook] |
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Lightning Storm Detector - Schematic diagram of a mass produced lightning
detector. The RF signal from lightning is quite strong and broad in spectrum so a
tuned circuit is not required at the antenna input stage. Too much sensitivity will
cause false alarms in a simple receiver such as this one. The circuit uses clever
pulse timing and integration techniques.... [Reverse engineered schematic by Stepan
Novotill] |
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Line Output/Flyback Transformer Tester - This is a 'ringer'-type tester I
(Bob Barker) originally designed for in-circuit testing of Line Output (Flyback)
transformers in TVs and computer monitors. After a couple of technician-years of
evaluation in actual servicing situations, it's also proved to be helpful in locating
shorted diodes, capacitors and deflection yokes in horizontal deflection stages. LOPT/FBT
condition is shown on an 8 LED 'bargraph' display..... |
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Linear Resistance Meter - ….(electronic schematic added 08/08) [Site is
under construction right now] |
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Linear wind power meter compensates for temperature - 13-Nov-08 Issue of EDN
Using a free-spinning anemometer for wind speed and a diode-connected transistor for
temperature sensing, this meter measures the wind power available for "green" power
generation.... [Design Idea by W Stephen Woodward, Chapel Hill, NC] |
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Live-line Detector - Detects the presence of a live mains conductor.
Minimum parts counting. (electronic circuit added 06/07/08) |
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