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1.5v Touch Activated Switch - A single 1.5v silver oxide button cell powers this
complete touch activated switch circuit for 5 years. It features both a normally open
and a normally closed set of solid-state switch thermals. It also has an adjustable
sensitivity, which can be set for a touch capacitance change as small as 1 picofarad.
….(designed by David A. Johnson) |
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12F675 as a Flip Flop - Code to make a 12F675 operate as a D-type or JK-type flip
flop. Since I implemented a D type flip flop using PIC Logic Elements I thought I
might go or way and implement an entire D type flip flop in a single PIC. This uses
edge triggered and port change status interrupts and was an opportunity to have a play
with interrupts on PIC.... (added 10/05) |
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3v Capacitance Proximity Switch - This circuit was designed to provide a touch
activated switch function without an external power supply. It draws so little power
that a single 3v battery will operate the circuit for many years. It is discussed in
more detail in the section on Capacitance Proximity Switch Technology. (Note: link is
off-site) ….(designed by David A. Johnson) |
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555 Bistable Circuit - Basic circuits and information about this
timer/oscillator. Scroll to find Bistable Circuit (11/06) |
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An SCR Flipflop for Alternating Flashing Light Bulbs - ….(electronic schematic
added 12/08) |
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AN-1150: COP8 FLASH ISP HANDBOOK-Intro to ISP - National Semiconductor Application
Note (app note added 2/06) |
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AN-1281:Bumped Die Flip Chip Packages - National Semiconductor Application Note
(app note added 2/06) |
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CMOS Toggle Flip Flop using Laser Pointer - The circuit below uses a CMOS dual D
flip flop (CD4013) to toggle a relay or other load with a momentary push button.
Several push buttons can be wired in parallel to control the relay from multiple
locations. A high level from the push button is coupled to the set line through a
small (0.1uF) capacitor. The high level from the Q output is inverted by the upper
transistor and supplies a low reset level to the reset line for about 400 mS, after
which time the reset line returns to a high state and resets the flip flop. The lower
flip flop section is configured for toggle operation and...(circuit / schematic design
added 6/06) |
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CMOS Toggle Flip Flop Using Push Button - The circuit below uses a CMOS dual D
flip flop (CD4013) to toggle a relay or other load with a momentary push button.
Several push buttons can be wired in parallel to control the relay from multiple....
(circuit added 7/02) |
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DAC & flip flops form constant current source - 04/23/09 EDN- Design Ideas, Using
two flip flops, you can program a serial-input DAC to produce a constant 4 mA.....(design
idea added 08/09) |
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Descrete Set/Reset Flip Flop - Here are two examples of bistable flip flops which
can be toggled between states with a single push button. When the button is pressed,
the capacitor connected to the base of the conducting transistor will charge to a
slightly higher voltage. When the button is released, the same capacitor will
discharge back to the previous voltage causing the transistor to turn off. The rising
voltage at the collector of the transistor that is turning off causes the opposite
transistor to turn on and the circuit remains in a stable state until....(circuit
added 05/09) |
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D-Flip/Flop One Shot Circuit - Yes you can use cheap D flip/flop logic circuits as
nice one-shot pulse generators. This schematic shows how the popular CD4013 and the
CD74HC74 can be used to generate pulses ranging from nanoseconds to seconds.
….(designed by David A. Johnson) |
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D-Flip/Flop Oscillators - Yes you can turn flip/flop ICs into low current
oscillators. This schematic shows you how. ….(designed by David A. Johnson) |
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Discrete BiStable Flip Flop - (electronic schematic / circuit added 4/02) |
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Discrete Set/Reset Flip Flop - This is an example of a set/reset flip flop using
discrete components. When power is applied, only one of the transistors will conduct
causing the other to remain off. The conducting transistor can be turned off by
grounding it's base through the push button which causes the collector voltage to rise
and turn on the opposite transistor. (added 04/04) |
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Dual flip flop forms simple delayed pulse generator - 04/17/08 EDN-Design Ideas: A
delayed pulse generator provides precision timing adjustments.....(design idea added
09/08) |
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Electronic circuit replaces mechanical push push switch - 09/28/06 EDN-Design
Ideas: Toggle-action circuit uses a low-cost momentary-contact switch.....(design idea
added 9/08) |
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Flashing LED Advertising Badge #1 - I have seen numerous flashing light badges at
trade shows and conventions. They are often handed out as gifts to promote some
business. The devices often use inefficient circuits, which cause the battery power
source to be quickly depleted. My circuit is simple but efficient enough to provide
months of continuous LED flashing. It also has a tiny push-button switch to turn on
and off the light flashing, extending battery power. ….(designed by David A. Johnson) |
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Flashing LED Advertising Badge #2 - This circuit is similar to flashing LED
advertising badge #1. . It uses a CD4013 dual D Flip/Flop IC. The 74HCT74 IC in #81
does not always work. As in #81, a single lithium battery will provide months of
continuous LED flashing. It also has a tiny push-button switch to turn on and off the
light flashing. ….(designed by David A. Johnson) |
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Flip Flop Circuit - In this project we examine one of the most valuable circuits
to be invented, the flip flop. Originally it was designed with VALVES, along with its
simpler version (without the two capacitors, called a bi-stable Multivibrator), it was
realised it …(circuits added 04/09) |
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Flip Flop Flashers Buzzers Etc - Several circuits here. The familiar astable
flip-flop circuit is a handy configuration for making flashers or generating
squarewaves. Here is a typical alternating LED flasher with the LEDs in the emitters
instead of collectors as is normally done. The bias resistors are directly
connected...(added 04/05/06) |
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Follow the Debouncing Flip Flops - 02/17/00 EDN-Design Ideas: /.....(design idea
added 2/06) |
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FPGA Circuit Emulates 74x74 Flip Flop - 10/12/95 EDN-Design Ideas:.....(design
idea added 11/05) |
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FPGA implements X.50 Division 3 recommendation04/13/00 EDN-Design Ideas: The
scheme in Figure 1a uses five delay cells and an XOR gate to configure the data stream
for the X.50 Division 3 recommendation of ITU-T. The X.50 recommendation defines the
fundamental parameters of a multiplexing scheme for interworking data .....(design
idea added 11/05) |
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Gated Oscillator Emulates a Flip Flop - 03/16/95 EDN-Design Ideas: (design idea
added 03/03/03) |
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High Current MOSFET Flip Flop with Debounced Pushbutton - This circuit was
adapted from the "Toggle Switch Debounced Pushbutton" by John Lundgren. It is
particularly useful in controlling a load from several locations where the load may be
switched on from one location and switched off from another. Any number of momentary
(N/O) switches or push buttons may be connected in parallel. The circuit....(circuit /
schematic design added 6/06) |
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Honeybee Counter - I designed a circuit similar to this one a long time ago to
help a beekeeper count the number of bees going into or out of a hive. The low power
circuit uses a slotted opto-sensor to detect the passing bees. The circuit advances an
electronic counting module whenever a honeybee passes through the sensor. The device
only counts the number of bees going through the sensor. A different circuit would be
needed to count the number of bees only going out or only coming into the hive.
….(designed by David A. Johnson) |
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Miniature Pushbutton On/Off Switch - In many battery powered devices, you would
like to turn the circuit on and off by pressing a small pushbutton switch. One press
turns the device on and second press turns it back off. The flip/flop circuit below
uses a minimum number of parts to perform this function. It operates from DC supply
voltage which can range from 2v to 6v. It draws very little current and takes up
little space. Yet, it can control up to one amp of current. The circuit uses a
single flip/flop device made by Texas Instruments. ... ….(designed by David A.
Johnson) |
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Monostable Flip Flops One Shot - (circuit added 7/02) |
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On/Off Flip/Flop Circuit With Automatic Timeout - This circuit is ideal when a
device needs to be turned on and off with a single pushbutton switch, but also needs
to turn itself off after some period of time. With the components shown, the output
will stay on for only about 20 seconds. ….(designed by David A. Johnson) |
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Pushbutton Oneshot & Latch - This circuit uses a single IC to convert a noisy
pushbutton switch signal into a clean pulse or a sustained push on-push off signal. It
can operate from 3v to 18v. ….(designed by David A. Johnson) |
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SCR Flipflop for Alternating Flashing Light Bulbs - ….(electronic schematic added
12/08) |
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Set/Reset Flip Flop - (electronic design added 10/06) |
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Soft On/Off Switch - Modern electronic equipment incorporate
"push-to-on-push-to-off" switches that do not make noise as with old equipment. An
example of this is the power button on a ATX computer cabinet. Here is a circuit that
does the same. It can be used to turn on/off .... (added 7/02) |
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Sound Controlled Flip Flop - Described here is a very inexpensive solution to many
phono-controlled applications like remote switching on, for instance, or activating a
camera, tape recorder, burglar alarms, toys, etc. The circuit given here employs a
condenser microphone as the pick-up. A two-stage amplifier built around a quad op-amp
IC LM324 offers a good gain to enable sound pick-up upto four metres. …. (added
10/05) |
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Spare flip flop stretches WR strobe for DSP - 07/20/95 EDN-Design Ideas: (design
idea added 2/06) |
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Spare gates form edge triggered flip flop - 03/16/95 EDN-Design Ideas: (design
idea added 2/06) |
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Telephone Line Based Audio Muting & Light on Circuit - FAIR WARNING -THIS SITE HAS
ANNOYING POP UP ADS. (added 4/02) |
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Telephone Line Based Audio Muting & Light-On Circuit - (electronic Circuit /
Schematic added 10/04) |
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Time to Dust Indicator - I thought about this circuit when I heard that a lot
cleaning personal in hotels were either dusting rooms more often than necessary or not
enough. I have not yet built and tested this circuit completely but in concept it
should work. The circuit draws very low current from a +3v battery and could be housed
in a package similar to a small ashtray. The assembly might be placed in a suitable
out of the way area to collect dust. It would alert a maid when it was time to dust
the room. The circuit detects dust with an infrared LED that is pulsed so its light
shines onto a smooth flat plate. Any dust settling onto the surface is detected by a
phototransistor, mounted at a 90-degree angle from the LED. When the dust reaches a
particular level, sufficient light is reflected into the phototransistor to change the
logic state of the circuit to an alarm condition. The alarm output could be connected
to a beeper, a flashing LED or to one of the LED flashing circuits in this hobby
circuit section. ….(designed by David A. Johnson) |
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Verilog Program Models metastable flip flop - 05/12/94 EDN-Design Ideas: (design
idea added 11/05) |
