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Hobby Circuits designed by Dave Johnson

Last Updated on: Tuesday, June 01, 2021 03:22 PM

List of Hobby Circuit Designs

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

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

Count Cars with Laser

Digital Counter using Pedometer

Divide a TTL Clock Signal by 1.5

Front Desk Service Beeper


Motorized Duck Decoy Timer

Poor Man's Timer

Press & Hold Latching Circuit

PWM Motor Controller uses a 555 Timer

Service Request Beeper

Timer for Darkroom Camera Shutter


Two-Transistor Low Power Oscillators

Watchdog Timer set for 36 Hrs

3 Minute LED Closet Light

60hz Clock Generator is Line Powered

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

Call-for-Service Beeper

Camera Shutter Time Measurement

Close Garage Door with Timer

Computer, Long Period, Watch Dog Timer


Hobby Circuits by Category

Dave's Circuits

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


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