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15V Battery Powers White LED Driver - 09/30/04 EDN-Design Ideas: Although white
LEDs are common in a variety of lighting applications, ir 3 to 4V forward-voltage drop
makes low-voltage applications challenging. Charge pumps and or ICs are available for
driving white LEDs, but y generally don't work with low supply voltage of 1.5V
in single-cell-battery applications.....(design idea added 1/05) |
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16 Stage Bidirectional LED Sequencer - The bi-directional sequencer uses a 4 bit
binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138)
to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides
the clock signal for the counter and the rate can be adjusted with the 500K pot. Two
additional Schmitt Trigger inverters are used as a SET/RESET latch to control the
counting direction (up or down). Be sure to use the 74HC14 and not the 74HCT14, the
74HCT14 may not work due to the low TTL input trigger level. When the highest count is
reached (1111) the low output...(circuit added 7/02) |
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16x16 LED Matrix & Driver - (circuit added 9/04) |
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17 LEDs Bar - (circuit / schematic design added 11/06) |
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18 LED Preset Followers - (electronic circuit added 11/06) |
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18 Stage LED Sequencer - The question sometimes comes up of how to cascade 4017
decade counters for more than 10 sequencial stages. The LED sequencer above shows a
possible solution using a few extra parts. When power is applied, the 15K resistor and
10uF cap at pin 15 will reset the counters to the zero count where pin 3 is at +12 and
all other outputs are at zero. The 2 diodes (1n914) and 15 resistor form a AND gate so
the clock pulse will be passed to the right side counter when the sequence starts.
When the right counter reaches the 10th count, pin 11 will move high enabling the AND
gate on the right to pass...(electronic schematic / circuit added 11/05) |
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1a Low Noise High Current LED Charge Pump with Independent Torch/Flash Current Control
- Linear Technology LT3216 (app note added 02/05) |
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1W White LED Night Light - As many of you know, I have a pet peeve with poorly
made LED night lights. Often, the light from the LED quickly fades, so within
months, the light is useless. I have posted several versions of modified night
lights using higher quality components. This circuit is yet another version,
which produces much more light than those other designs. The circuit brings together
two high power white LEDs made by Cree with a compact AC to DC power supply from Bias
Power..... ….(designed by David A. Johnson) |
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2 Line Telephone Line Status Indicator - Many home businesses use multiple phone
lines. This circuit gives you a visual indication when a line is in operation. The two
AA battery cells should provide enough power for about one year of operation. The
circuit is line polarity insensitive. ….(designed by David A. Johnson) |
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2 Transistor 2 LED Flasher - (Tony van Roon's circuit / schematic design added
6/06) |
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2 Transistor LED Flasher - This is a classic 2 transistor astable multivibrator.
Many other NPN small signal or switching transistors can be used, including 2N4401,
PN2222 or 2N2222 using the circuit on the left. The circuit can also be inverted using
PNP transistors(circuit / schematic design added 6/06) |
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2 Transistor LED Flasher (Bill Bowden) - This circuit will flash a bright LED (500
mcd) as an attention getting device or fack car alarm. Component values are not
cirtical and other transistors may be…...(circuit added 7/02) |
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20ma LED Ballast - I use this circuit for general use to power white LEDs, like a
headset light I use on my desk and a keyboard light for my computer. I built it into a
tiny Radio Shack project box (270-288), which y no longer sell. I put heat-shrink
tubing around female output connector (RS P/N 273-1743), ....Designed by Andrew
R. Morris (added 9/05) |
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230V Rotating & Blinking LED - This design can be of some interest for those
wanting striking light signs, as it can drive up to three 230V lamp strings in three
operating modes. The 15V dc supply is obtained from a nominal 230/24V center tapped ac
transformer (T1) and a full wave rectifier....(electronic design added 09/08) |
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25 Light Sequencer using Xmas Lamps - This circuit above can drive 25 small Xmas
lights. The lights operate at about 200mA and 3 volts. The supply voltage is set to 5
volts and the 4017 counter output will drop about a volt using the 2N3053 transistors.
The voltage on the emitters of the rows transistors will be about 0.7 volts less than
the base so the lamp voltage will be about 3 volts. You can ....(schematic added
02/09) |
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28 LED Clock Timer 72 LED Clock - programmable clock Timer circuit that uses
individual LEDs to indicate hours and minutes (added 4/02) |
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3-Colour Display using Bicolour LEDs - (electronic Circuit / Schematic added
10/04) |
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3V LED Chaser - ….(electronic schematic added 03/08) |
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40 LED Bicycle Light 555 Timer 6 Volt - The 555 circuit below is a flashing
bicycle light powered with four C,D or AA cells (6 volts). Two sets of 20 LEDs will
alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K
for R1, 150K for R2 and a 1uF capacitor). Time intervals for the two lamps are about
107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs)....(circuit
added 7/02) |
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40kHz TV-VCR Light Source Repeater - This circuit is designed to be placed
directly in front of a standard TV or VCR remote. The exiting light pulses produced by
the circuit match the pulses from the remote but are about 10 times more powerful.
Using the device, the remote can operate a TV or VCR over three times the normal
distance. ….(designed by David A. Johnson) |
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5 Lamp/ LED Flash Driver - (schematic added 09/08) |
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555 timer drives multiple LEDs from one NiMH cell - 10/02/08 EDN-Design Ideas: ,
Using a CMOS 555 timer, you can drive seven high-brightness LEDs from a single 1.25V
cell.....(design idea added 08/09) |
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5x7 Display - Sit back and take a big breath. You are about to take part in one of
the best microcomputer (microprocessor) projects you have seen. It uses a PIC16F84
micro and you will be shown how to program the chip to create quite amazing effects.
It's a simple project and you will be starting at the beginning of programming, so
don't worry if you have never worked with a microprocessor before....(added circuit
05/07) |
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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 ….(added 08/08/08) |
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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....(added 6/07) |
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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. (added 7/06) ….(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 (bowden) - 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....(circuit added 7/02) |
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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....(electronic circuit
added 10/05) |
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9 Second LED Relay 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,....(circuit / schematic design added 6/06) |
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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. (added 7/06) ….(designed by David A. Johnson) |
