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µC Implements Pushbutton Light Dimmers - 06/18/98 EDN-Design Ideas: A project
required building a synchronous-demodulator circuit to track a line drawn on paper.
The beauty of the synchronous-modulator/demodulator approach is its inherent noise
rejection. The method rejects nearly all out-of-band noise, whether from internal
drift or external illumination. This rejection is a boon in optical tracking, where
the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and
temperature drifts. The circuit in Figure 1 is inexpensive, and it operates from 5V
dc. The circuit scans eight LED/sensor pairs every 22 msec and stores the result in
eight sample/hold (S/H)capacitors for interrogation by a µP-driven ADC. The purpose of
the circuit is to determine which sensor is above the line.....(design idea added
08/05) |
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1 to 10 Volt Analog Control Protocol - (design circuit added 8/02) |
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1 Watt Fluorescent Lamp Night Light - If you are tired of replacing small night
light lamps, try this circuit. The line powered circuit uses a long life cold cathode
fluorescent lamp. A simple charge pump technique runs the lamp without any
transformer. ….(designed by David A. Johnson) |
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1.5 Hour Lamp Fader (Sunset Lamp) - the sunset lamp comes on at full brightness
and then slowly fades out over 1.5 hours time and stays off until power is recycled.
(design added 5/09) |
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1.5 Volt LED Flashers (Bowden) - The LED flasher circuits below operate on a
single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED
flasher IC and requires only a timing capacitor and LED. The top left circuit,
designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery
voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used
as a squarewave oscillator that establishes the flash rate while a third section is
used as a buffer that charges the capacitor in series with a 470 .... (added 4/02) |
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10 Stage LED Sequencer (Bowden) - The 4017 is a CMOS decade counter with 10
decoded outputs. Inputs include a clock (pin 14), a reset (pin 15), and a clock
inhibit (pin 13)….(design added 5?09) |
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10 Stage Light Sequencer - schematic only -- flashes 10 low voltage bulbs,
operates at10-25-Volt voltage, in PDF format, text in Finnish (added 4/02) |
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10 to 100 LED Sequencer Using a Matrix - The circuit above illustrates using a
10x10 matrix to sequence up to 100 LEDs with just three ICs and 20 transistors. The
two 4017 decade counters control the 10 rows and 10 columns so that one LED is
selected depending on the output of the decade counters. The LED circuit is drawn
showing 25 LEDs and 10 transistors but can be expanded up to a 100 by using sucessive
stages of the 4017 counters. For example, to expand the circuit to 60 LEDs for
displaying minutes or seconds of a clock, the rows counter could be reset from pin 12
(carry out) rather than pin 1 as shown, and the columns..(electronic design added
6/07) |
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12 Stage Neon Sequencer NE 2/NE 51 - This circuit is similar to the LED clock
using 12 neon indicator lamps instead of LEDs. It operates from 2 high capacity ni-cad
cells (2.5 volts) which keep it going for a couple weeks. High voltage (70 volts) for
the neon lamps is obtained from a small switching power supply using a 74HC14 Schmitt
trigger squarewave oscillator, high voltage switching transistor.....(added 4/02) |
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12 Volt DC Fluorescent Lamp Driver (Aaron Cake) - This fluorescent lamp driver
uses a normal 120 to 6V step-down transformer in reverse to step12V to about350-Volt
to drive a lamp without need to warm filaments. (added 04/03/02) |
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12 Volt Lamp Dimmer (using a pot) - Here is a 12 volt / 2 amp lamp dimmer that can
be used to dim a standard 25 watt automobile brake or backup bulb by controlling the
duty cycle of a astable 555 timer oscillator. When the wiper of the potentiometer is
at the uppermost position, the capacitor will charge quickly through both 1K
resistor....(added 05/09) |
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12 Volt Lamp Fader (LEDs or incandescent) - This circuit is similar to the "Fading
Red Eyes" circuit (in the LED section) used to fade a pair of red LEDs. In this
version, the lamps are faded by varying the duty cycle so that higher power
incandescent lamps can be used without much power loss. The switching waveform is
generated by comparing two linear ramps....(electronic schematic / circuit added
05/09) |
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120 VAC Lamp Chaser using Solid State Relays - This circuit is basically the same
as the 10 channel LED sequencer with the addition of solid state relays to control the
AC lamps. The relay shown in the diagram is a Radio Shack 3 amp unit (part no.
275-310) that requires 1.2 volts DC to activate. No current spec was given but I
assume it needs just a few....(electronic circuit added 7/03) |
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120 VAC Lamp Dimmer - The full wave phase control circuit below was found in a RCA
power circuits book from 1969. The load is placed in series with the AC line and the
four diodes provide a full wave rectified voltage to the anode of a SCR. Two small
signal transistors are connected in a switch configuration so that when the voltage on
the 2.2uF....(circuit added 7/02) |
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120 Volt AC Lamp Chaser using Solid State Relays - This circuit is similar to
LED clock using12 neon indicator lamps instead of LEDs. It operates from2 high
capacity ni-cad cells (2.5 volts) which keep it going for a couple weeks. High voltage
(70 volts) for neon lamps is obtained from a small ...(added 4/02) |
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120 Volt AC Lamp Dimmer Full Wave SCR - (circuit added 7/02) |
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120VAC Lamp Chaser - Uses Solid State Relays (electronic circuit added 4/05) |
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12V DC Fluorescent Lamp Driver (Aaron Cake) - (electronic circuit added 4/05) |
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12v Fluorescent Inverter - This is a low-cost project for 20 or 40 watt
fluorescent tubes. However the most efficient is to use a 40 watt tube (or two 20 watt
tubes in series). It's a circuit you can put together from junk box components or
build from a kit. It's very simple to build and requires no printed circuit
board....(project added 04/09) |
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12V high side PWM Motor/Light Controller - scroll down (circuit 6/07) |
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12v Light/Dark Lamp Switch - At night, this circuit will route current to a 12v
lamp, turning it on. (added 7/06) ….(designed by David A. Johnson) |
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12v Light/Dark Switch - Often, for certain low voltage lighting systems; you would
like to turn off the lights during the bright light of the day. Most commercial
day/night switches are designed for AC lighting. The circuit below was designed
for a 12v DC system. But, it could be modified for other voltage as well.
It uses an inexpensive phototransistor as the light detector. An n-channel FET
is used to switch power to the lights. A transistor circuit is included to
provide some hysteresis. This keeps the circuit from fluttering the light during
the transition from day to night and night to day. It is recommended that a
plastic tube be placed over the transistor to prevent it from being illuminated by the
lights it is controlling. By selecting the appropriate power FET, the circuit
could control over 100 watts worth of 12v lighting. (July 27, 2008) ….(designed by
David A. Johnson) |
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12V low side PWM Motor/Light Controller - scroll down (circuit 6/07) |
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12VDC Fluorescent Lamp Driver - A number of people have been unable to find the
transformer needed for the Black Light project, so I looked around to see if I could
find a fluorescent lamp driver that does not require any special components. I finally
found one in Electronics Now....(electronic design added 6/07) |
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12 Volt Strobe Circuit - this circuit uses 12V DC instead of mains AC. This is
very good idea if you don't want to mess with direct mains voltage connected circuit
or you want to run stroboscope from batteries. (added 4/02) |
