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Peak Hour
Timer - Electrical appliances like refrigerators and
air-conditioners consume heavy current if the line voltage drops during the peak hours between 6 pm and 9 pm. If
there is no low-voltage cut-off in these appliances, it will cause wastage of current and heating of the
appliances. Over-heating may, in turn, reduce the efficiency of the compressors of these appliances. . . . [©
EFY Enterprises Pvt. Ltd. All rights reserved.]
Pedometer - Pedometer has a range of 9. 950 meters with2-digits. Slip it in pants pocket for walking and
jogging. . . [Flavio Dellepiane's web site]
Period timer for aquarium, sprinklers and more - Turn on the sprinkler or the aquarium lighting for the same period of the day. You can
choose to operate the output by every 2nd, 3rd, . . . day only. There is a manual start/stop button to
immediately turn on or off the output, and a disable button to completely turn off automatic operation. . . .
[designed by Peter Jakab]
Periodic Timer - A switched timer with equal make and equal space periods timing adjustable from over 6
minutes to 38 minutes. . . . [Circuit by Andy Collison]
Periodically
On-Off Mosquito Repellent - Here is a circuit that
automatically switches on and off the mosquito repellent after preset time interval, thus controlling the release
of toxic vapours into the room. . . . [© EFY Enterprises Pvt. Ltd. All rights reserved.]
Person Counter - The integrated circuit is a 4516 up/down counter. Diode 2 determines the count direction.
The value of the resistors R’ depends on the type of diode used. (You will probably need resistors in the range
100k to 1M. ) When entering the room, the beam illuminating diode 1 must be cut first. This causes the counter to
count UP one. If (when a person leaves the room) the beam illuminating diode 2 is cut and while this beam is
still cut the beam illuminating diode 1 is cut, the counter will count down one. The output can be used (with a
relay and driver) to switch on a light when a person first enters the room and then to switch the light off when
the last person leaves the room (maximum number of people, 15). . . . [© David Hoult 2013]
Photo Timer Circuit - . . . [by IQ Technologies Industry, unless otherwise noted online]
Photo-Counter - You can use this gadget to detect whether somebody opened your cupboard or drawer in your
absence. The gadget is small and highly power-efficient. . . . [© EFY Enterprises Pvt. Ltd. All rights
reserved.]
Phototimer
Controls Load - 04/18/02 EDN Design Idea In industrial
and home applications, the need sometimes exists for a device that, after activation by some physical effect,
such as light, temperature, or sound, switches a load on for a predetermined time. The load, such as a lamp,
motor, solenoid, or heater, usually derives its power from the ac line. . . [by Abel Raynus, Armatron
International, Melrose, MA]
PIC Digital Clock Timer - This clock timer uses a PIC16F628 microcontroller to display 3 and 1/2 digit time and
control an external load. The clock includes a calendar with leap year and optional daylight savings adjustments.
The timer output can be set from 1 to 59 minutes and manually switched on and off. The clock also has a
correction feature that allows an additional second to be added every so many hours to compensate for a slightly
slow running oscillator. The oscillator uses a common 32. 768 KHz watch crystal and the frequency can be adjusted
slightly with the 24pF capacitor on the right side of the crystal. . . [Bill Bowden]
PIC Tock Video Clock - PIC-Tock is a video clock using a PIC16C61. In the tradition of Marv Newland's "Bambi Meets
Godzilla", there is far too much ROM space spent on credits, which are smooth-scrolled horizontally on the bottom
of the screen. . . . [Circuit designed by Eric Smith]
PIC12C509
Gym Timer - . . . [MicrochipC by Mike Pearce]
PIC16F628 Digital Clock Timer - Can be programmed from 1 to 59 minutes. . . [Bill Bowden]
PIC16F84 Miniature Real Time
Controller - Build a simple real-time controller with
PIC16F84 running at low power X-tal 32, 768Hz. Daily scheduler for 6-channel resided in 64-byte EEPROM can easily
be preprogrammedusing Nigel PicProg. . . [Wichit Sirichote, designer]
PLD implements fast four-phase clock generator - 10/27/94 EDN Design Idea The circuit in Fig 1a can clock pipelined logic in PLDs by an
external agent at one-half the usual frequency. You can use this circuit when designing pipelined ALUs and
switched-capacitor circuits. I used this circuit to drive a 40M-sample/sec CMOS flash. . . [by Said Jackson,
Hamburg, Germany]
Police Lights - These two circuits flash the left LEDs 3 times then the right LEDs 3 times, then repeats.
The only difference is the choice of chips. . . . [Designer's name is not given}
Police Siren - The Police Siren circuit uses two 555's to produce an up-down wailing sound. The first 555
is wired as a low-frequency oscillator to control the VOLTAGE CONTROL pin 5 of the second 555. /. . . .
[Designer's name is not given}
Poor Man's Timer - Often during testing of certain equipment and components, you would like to keep track of
the elapsed time in hours, minutes and seconds. There are some nice commercial digital timers and counters
available for just this sort of application. However, . . . [Hobby Circuit designed by Dave Johnson P.E.,
08/24/08]
Positive Trigger Timer
Circuit - This 555 timer is designed unusually to give a
positive output through a control over its reset pin. Usually the timer IC 555 is triggered by applying a
negative going pulse to its trigger pin 2. This timer is triggered through a positive pulse in its reset pin. In
the monostable mode IC 555 starts timing cycle when a negative. . . [Circuit Posted by D Mohankumar]
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