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Hobby Circuits designed by Dave Johnson

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

Text & Graphics Copyright © David A. Johnson, PE  --  ALL Rights Reserved.
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Alarm Circuits

Circuits Designed by David Johnson, P.E. :

Fake Car Alarm Light

Flashing Light to simulate Car Alarm

Footstep Alarm for Human Traffic

Freeze Alarm

Freezer Over-Temperature Alarm

Freezing Temperature Alarm

Front End + Power Supply Circuits of the Electric Filed Disturbance Monitor

Human Footstep Alarm

Indicates when it is Time to Dust

Indicates when it is Time to Dust

Indicator for Bad Light Bulb

It's Time to Dust Indicator

Knocking rings Doorbell

Light/Dark Activated Motion Detector

Low Voltage 120vAC Power Line Alarm

Micro Power Over-Temperature Alarm

Monitors Pump Motor

Motion Alarm using piezo Device

Next-Generation Star-Trek Doorbell

Over-Temperature Micro-Power Alarm

Piezoelectric Device used for Motion Alarm

Power Line Alarm

Power Loss Beeper

Pump Motor Monitor

Remote Doorbell Beeper

Shadow Activated Motion Detector

Simple Circuit Wire Security Loop Alarm

Snow Depth Alarm

Star Trek Doorbell

Still Another Very Loud piezo Alarm Beeper

Sweeping Siren Alarm-3 volts

Time to Dust

Touch Alarm for Door Knob

Under/Over Voltage Alarm on AC Line

Unplugged Appliance Alarm

Unplugged Power Cord Alarm

Water Cistern Level Alarm

Water Seepage Alarm

Wire Loop Security Alarm
120 VAC Low Voltage Alarm

3v Sweeping Siren Alarm

AC Line Under/Over Voltage Alarm

AC Power Loss Alarm

Alarm Beeps when the “Check Engine” Light Turns On

Alarm Discriminator + Battery Monitor of the Electric Field Disturbance Monitor

Alarm for a Chain Link Fence

Alarm Sounds At Freezing Temperatures

Alarm Sounds when Phone Line is Cut

Alarm sounds when Power Cord is Unplugged

Alarm sounds when Water is Detected

Alarm-Piezo Device Detects Motion

Another Very Loud piezo Alarm Beeper

Appliance Unplugged Alarm

Bad Light Bulb Indicator

Basement Doorbell Beeper

Basement Remote Doorbell

Battery-Powered Freezer Alarm

Chain Link Fence Alarm

Circuit Monitors Power Loss

Clip-on AC Current Indicator Circuit

Cut Phone Line Alarm

Detect Motion with a Piezo Device

Detector for Human Footsteps

Detects Low Voltage 120VAC Power Line 

Detects Shadow Activated Motion

Doggie Water Dispenser Alarm

Door Knob Alarm

Door Knock Beeper

Doorbell heard in Basement

Earthquake Alarm Circuit

Electric Field Disturbance Monitor-Alarm Discriminator + Battery Monitor


Hobby Circuits by Category

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



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