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12 Sec to 90 min Relay: (added 2/06) |
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120 Volt AC Lamp Chaser using Solid State Relays: This circuit is similar to
the 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 the neon lamps is obtained from a small switching power supply using a
74HC14 Schmitt trigger Squarewave oscillator, high voltage switching transistor, and10
mH high Q inductor. Most any small PNP transistors can be used that have a C/E voltage
rating of 80 or more. (Circuit / schematic design added 6/06) |
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2 Lead Solid State Breaker Resets Itself: 03/30/95 EDN-Design Ideas / (added
03/03) - Simple dc circuit breaker can protect a power supply from the ever-present
screwdriver or even isolate a satellites dual power system from a short circuit in one
subsystem |
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555 Timer MonoStable Circuit using Pushbutton: (Electronic Schematic /
circuit added 4/02) |
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741 Based Light Sensor: CdS photocell used for light/dark controlled relay
(Electronic circuit added 5/02) |
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8-Way Relay Interface
Board for PC Parallel Printer Port: (Circuit / schematic design added 6/06) |
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9 Second LED Relay Timer: (Electronic Schematic / circuit added 4/02) |
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Alternating on/Off Control: This circuit uses three easily available 555
timer ICs. All three work as astable multivibrators. The first 555 has an on period
and off period equal to 1 sec. This IC controls the on/ off periods of the other 2
555s which are used to flash two bulbs through the relay contacts. The flashing occurs
at a rate of 4 flashes per second. The diodes are used to protect the 555 ICs from
peaks. The relays should have an impedance greater than 50ohms i.e, they should not
draw a current more than 200mA.... (added 10/05) |
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Analog Switch Lowers relay Power consumption: 12/20/01 EDN Design Ideas
/ (added 1/05) Designers often use relays as electrically controlled
switches. Unlike transistors, their switch contacts are electrically isolated from the
control input. However, the power dissipation in a relay coil may render the device
unattractive in battery-powered applications. You can lower this dissipation by adding
an analog switch that allows the relay to operate at a lower voltage (Figure 1). ... |
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Assorted relay Control circuits: (Electronic circuit added 4/05) |
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Basic Stamp I and PC Relay Controller: (Electronic circuit added 4/05) |
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Circuit Drives Latching Relays: 02/01/96 EDN-Design Ideas / (Electronic
Circuit diagram added 03/03) |
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Circuit removes relay contact Bounce: 11/27/03 EDN Design Ideas /
(added 1/05) Advances in semiconductor technology have allowed ICs to replace
many mechanical relays, but relays still dominate in high-current circuits that must
stand off high voltages of arbitrary polarity. Contact bounce in those relays,
however, can prove troublesome to downstream circuitry. One approach to contact bounce
combines a relay with a hot-swap controller.... |
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CMOS Toggle Flip Flop using Laser Pointer: (added 10/05) |
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CMOS Toggle Flip Flop using Push Button (CD4013): This is fairly complex and
not the best toggle circuit. (added 10/05) |
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Control 120 Volt AC Relay with TTL: (Electronic Schematic / circuit added
4/02) |
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Control 120VAC Relay with
TTL: (Circuit / schematic design added 6/06) |
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Controlling Relays with Logic Voltages: (Electronic Schematic / circuit
added 4/02) |
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Countdown timer with Relay: (added 8/03) |
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Dancing LEDs: A LED sequencer, following the rhythm of music or speech 9
Volt Battery-operated portable unit (Circuit added 9/04) |
|
Dark/Light Activated Relay: (Circuit / schematic design added 6/06) |
|
Electronic Thermostat Relay Circuit: (Electronic Schematic / circuit added
4/02) |
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Inexpensive Relays Form
Digital Potentiometer: 03/13/98 EDN-Design Ideas / (Circuit / schematic design
added 6/06) -- Build a digitally controlable isolated potentiometer that
can tolerate voltages up to 60-Volt dc |
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Infrared Relay with Relay Output: (Electronic circuit added 4/05) |
|
KD2BD Video Operated Relay : turns on relay if there is video signal present
in the input (Electronic circuit added 5/02) |
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Key reading circuit saves I/O pins: 02/06/03 EDN-Design Ideas / (added
8/03) Some microcontroller applications usually use too many I/O pins to read keys or
onboard switches; in many cases, few pins remain available for other uses. Some
alternative ways to read keys yield more free pins. First, consider some ways to
effect key reading. Table 1 presents a comparison of four methods with references to
circuit configurations (figures 1, 2, 3, and 4) |
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Light activated relay #1: (Circuit / schematic design added 6/06) |
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Light Activated Relay (toggled): (added 11/05) |
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Light/Dark Detector: (Electronic Schematic / circuit added 4/02) |
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Load Sensing Automatic Switch: apply power to the entire audio system by
turning on1-item, simple circuit (Electronic circuit added 5/02) |
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Long Duration--1 min to 20 hrs Relay: (added 2/06) |
