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Hobby Circuits designed by Dave Johnson

Last Updated on: Wednesday, November 22, 2017 02:30 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!




Safety Circuits
 
Circuits Designed by David Johnson, P.E. :
Beeper indicates Check Engine

Check Engine Beeper

Circuit Protects from Battery Polarity Reversal

Detects Low Voltage 120VAC Power Line 

Infrared Safety Switch

Low Voltage 120vAC Power Line Alarm

Modified LED Night Light

Night Light from White LED

One-Watt White LED Night Light

Power Line Alarm

Protects from Battery Polarity Reversal

Replace a Pushbutton Switch with this Infrared Safety Switch

Simple Circuit for White LED Night Light

Sound Triggered Night Light

120 VAC Low Voltage Alarm

12v Battery Load Cutout Circuit

18v AC to DC Power Supply

1W White LED Night Light

AC Power Loss Alarm

AC to DC 18V Power Supply

Alarm Beeps when the “Check Engine” Light Turns On

Battery (12v) Load Cutout Circuit


 

Hobby Circuits by Category

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