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LED (Light
Emitting Diodes) Circuits Page 1e
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Last Updated on:
Wednesday, November 29, 2017 05:40 AM |
| Circuits Designed by Dave
Johnson, P.E. : |
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9v Battery Voltage Monitor - This circuit turns on a LED whenever the
voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.
It uses a LTC1440 comparator, which also contains a 1.18v reference diode. In
standby mode, the circuit draws only 4uA.....
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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60 LED Clock - As you can see see we have changed the circuit a
little. For example, the 4093 NAND gate is now set to exactly 1 second
clock pulses. The clock rate is determined by the resistor and capacitor
combination on the 4093. If the resistor is 220k ohms and the capacitor is
4.7uf then …..... |
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60 LED Clock (Bowden) - This 1.5 volt led fasher runs more than
a year on a single 'd" cell and alternately flashes 2 LEDs at about a 1
second rate. The circuit employs a 74HC14 CMOS hex inverter that will
operate at very low voltages (less than 1 volt). One section is used as a
squarewave oscillator (pins 1 and 2), while the others are wired to
produce a short 10mS pulse on alternate edges of the square wave so the
LEDs will alternate back and forth..... |
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60 Watt Lamp with Auxiliary 14v LED Lamp - This circuit controls
power to a standard 60 watt lamp plus generates an auxiliary 14v DC supply
which can power an automotive style 12 LED array.…. [Designed by David A.
Johnson] |
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7 by 10 LED Moving Sign 27c512 Eprom - This sign I designed uses
no microprocessor. It has an eprom and multiple counters. As in most
electric signs, the LEDs are matrixed, and strobed very
quickly….(electronic circuit added 4/05) |
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7 Segment LED Counter (Aaron Cake) - This simple counter can be used to count
pulses, as the basis for a customer counter (like you see at the doors of some
stores), or for anything else that may be counted. The circuit accepts any TTL
compatible logic signal, and can be expanded easily (see Notes).....(circuit /
schematic design added 7/02) |
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72 LED Clock - In the circuit above, 60 individual LEDs are used to indicate
the minutes of a clock and 12 LEDs indicate hours. The power supply and time base
circuitry is the same as described in the 28 LED clock circuit above. The minutes
section of the clock is comprised of eight 74HCT164 shift registers cascaded so that a
single bit can be recirculated through the 60 stages i..... [Bill Bowden] |
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7x7 Monochrome LED Display - This is an easy to build 7x7 led matrix. You
can use it as a casebadge, for example. The device comes to it rights the most when
showing animations. See 7x7led.avi for a short movie showing a rotating torus. As you
can see the schematic is quite simple. An AVR, a few transistors, com resistors and
some logic to convert RS232 to TTL. [b:d36eaf5672]Features[/b:d36eaf5672] 7x7 led
matrix 127 grades of brightness per led Interface to PC: RS232 Microcontroller:
ATTiny2313. License: GPL [b:d36eaf5672]Construction[/b:d36eaf5672] Let's start with
the led-array. Best is to build it row by.... |
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8 Random Flashing LEDs - This project flashes eight LEDs in an apparently
random manner. It uses a 4060 combined counter and display driver IC which is designed
for driving 7-segment LED displays. The sequence is not really random because seven of
LEDs would normally be display segments, eighth LED is driven by an output
that is normally used for driving furr counters.....(added 9/05) |
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8 Stage LED VU Meter - The circuit below uses two quad voltage comparators
(LM339) to illuminate a series of 8 LEDs indicating volume level. Each of the 8
comparators is biased at increasing voltages set by the voltage divider so that the
lower right LED comes on first when the input is about 400 millivolts or about 22
milliwatts peak in an 8 ohm system. The divider voltages are set so that each LED....
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9 Second Digital Readout Countdown Timer - This circuit provides a visual 9
second delay using a 7 segment digital readout LED. When the switch is closed, the
CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output
held high. When the switch is opened,… [Bill Bowden] |
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9v Battery Voltage Monitor - This circuit turns on a LED whenever the
voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.
It uses a LTC1440 comparator, which also contains a 1.18v reference diode. In
standby mode, the circuit draws only 4uA..... [Hobby Corner Circuit by Dave Johnson] |
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