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Hobby Circuits designed by Dave Johnson

Last Updated on: Tuesday, October 24, 2017 03:04 PM

List of Dave's Circuit Designs

Text & Graphics Copyright David A. Johnson, PE  --  ALL Rights Reserved.
LINKING to Dave's circuits is permitted but DO NOT COPY CONTENT to your WEB SITE server!

Timer / Counter Circuits
Circuits Designed by David Johnson, P.E. :

Digital Counter using Pedometer

Divide a TTL Clock Signal by 1.5

Divide By 1.5 Counter

Dusk To Dawn Latching Relay

Front Desk Service Beeper

Garage Door Timer

Laser Used as Vehicular Traffic Counter


Line Powered 60hz Clock Generator

Long Period Computer Watch Dog Timer

Low Power Oscillators

Motorized Duck Decoy Timer

On/Off Flip/Flop Circuit with Automatic Timeout

On/Off Latch Circuit with 2 Second Delay

On/off Pushbutton Switch with 30 Minute Timeout

Poor Man's Timer

Press & Hold Latching Circuit

Pushbutton Activates Service Request Beeper

PWM Motor Controller uses a 555 Timer

Service Request Beeper

Three-Minute Closet Light

Timer for Darkroom Camera Shutter

Two Transistor Oscillators

Two-Transistor Low Power Oscillators

Watchdog Timer set for 36 Hrs

2 Transistor Oscillators

3 Minute LED Closet Light

36-Hour Watchdog Timer

3-Minute Closet Light

3-Minute Closet Light #2

555 Timer Forms Simple Circuit PWM Motor Controller

60hz Clock Generator is Line Powered

Accurate One Shot Pulse Generator

Automatic Timeout included with this On/Off Flip/flop Circuit

Call-for-Service Beeper

Camera Shutter Time Measurement

Chicken Coop Door Opener with Timer

Circuit Forms Divide By 1.5 Counter

Closet Light with Automatic 3-Minute Timeout

Computer, Long Period, Watch Dog Timer

Count Cars with Laser

Darkroom Camera Shutter Timer


Hobby Circuits by Category

  David A. Johnson, P.E. about these circuits



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