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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!

Micro Power Circuits
Circuits Designed by David Johnson, P.E. :

LED Flasher-Wireless Circuit

LED Flashing Badge #1

LED Flashing Badge #2

Light Detector with High Ambient Light Immunity

Light/Dark Activated Motion Detector

Line Status Indicator for 1 Telephone Line

LM317 adjustable voltage regulator used in Battery Eliminator Circuit

Low Battery Voltage Flasher

Low Frequency Oscillator draws only 2 Nanoamps

Low Power 40KHz Light Detector

Machine Vibration Triggers Hour Meter

Micro Power 40Khz Burst Laser Diode Driver

Micro Power Over-Temperature Alarm

Micropower CMOS Oscillator, Draws Only 0.5ua

Micropower Pulse Generator

Momentary Touch Activated Switch

Monitors Pump Motor

Motion Alarm using piezo Device

Nine-Volt Battery Eliminator

Nine-Volt Battery Voltage Monitor

One-Line Telephone Line Status Indicator

Optical Interrupter Draws Microamps

Oscillator Draws 2 Nanoamps

Over-Temperature Micro-Power Alarm

Piezoelectric Device used for Motion Alarm

Pop Free Microphone On/Off Switch Circuit

Precision Fullwave Rectifier

Precision Ultra Lower Power Oscillator

Pulse Generator uses Micropower

Pump Motor Monitor


Replace a Pushbutton Switch with this Infrared Safety Switch

Shadow Activated Motion Detector

Simple Circuit Wire Security Loop Alarm

Slotted-Type Optical Interrupter Draws Microamps

Solid State Relay Requires Only 50ua Drive Current

SSR Requires Ultra Low Control Current

Supercapacitor Voltage Limiting Circuit

Switch Detects Audio Signal

Ten-Second Ultra Lower Power Oscillator

Tester for Modulated Light

Thermocouple Temperature Activates Relay

Three-Volt Low Battery Voltage Flasher

Three-Volt Powered Very Loud Beeper

Touch Activated Switch

Touch Alarm for Door Knob

Transistor-Switch Detects Audio Signal

Two Transistor Oscillators

Two-Transistor Low Power Oscillators

Ultra Low Current Oscillator

Ultra Low Power 32Khz Crystal Oscillator

Ultra Low Power Latching Relay Circuit

Ultra Low Power LED Flasher

Ultra Lower Power Oscillator

Universal Flasher using a Latching Relay

Version a of 1.5v LED Flasher

Very Loud 3v Powered Beeper

Very Low Voltage Oscillator Circuit

Voltage Limiting with a Supercapacitor

Voltage Monitor for a 9v Battery

Watt-Hour Meter Monitor

Wire Loop Security Alarm

1 Line Telephone Line Status Indicator

1.5v LED Flasher Version A

1.5V Touch Activated Switch

10 Second Ultra Lower Power Oscillator

12v Touch Switch Exciter Circuit

2 Transistor Oscillators

3 Volt Low Battery Voltage Flasher

32Khz Ultra Low Power Crystal Oscillator

3v 2hz Oscillator

3v Powered Loud Beeper

40Khz Burst Laser Diode Driver

40Khz Light Detector with High Ambient Light Immunity

40KHz Light Detector with Sunlight Immunity

50ua Current Drives Solid State Relay Requires Only

9v Battery Eliminator

9v Battery Voltage Monitor

9V Pulse Generator

Advertising Badge #1 with Flashing LED

Advertising Badge #2 with Flashing LED

Alarm Sounds At Freezing Temperatures

Alarm-Piezo Device Detects Motion

Audio Activated Switch

Basement Remote Doorbell

Battery Eliminator

Battery Free LED Flasher

Battery-Powered Freezer Alarm

Battery-Powered LED Flashing Advertising #2

Capacitance Touch Switch

Charge Pump Efficiently Divides Supply Voltage 

Cheap Low Power 3v 2hz Oscillator

Circuit Eliminates 9v Battery

Circuit Forms Ideal Diode Function

Clear Fluid Monitor


CMOS Oscillator, Draws Only 0.5ua

Detects Shadow Activated Motion

Detector/Switch for Audio Signal

Door Knob Alarm

Door Knock Beeper

Exciter Circuit-12v Touch Switch

Flashing LED Advertising Badge #1

Freeze Alarm

Freezer Over-Temperature Alarm

Freezing Temperature Alarm

High Ambient Light Immunity with a 40Khz Light Detector

High Temperature Thermocouple activates Relay

Highly Stable Lower Power Oscillator

Hour Meter triggered by Machine Vibration

Indicates Battery Charge Current

Infrared Safety Switch

Knocking rings Doorbell

LED Flasher needs only 1.5 VOLTS

LED Flasher that is Battery Free

Low Power LED Flasher

Low-power optical interrupter


Hobby Circuits by Category

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



Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

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