Indicator Electronic Circuits, page 5

Indicator Circuits Page 5
#'s - B C - F G - O P - S T - Z
Last Updated on: Friday, October 16, 2009 03:43 AM

Circuits designed by Dave Johnson, P.E. :

Moving Air Indicator
Many months ago a Discover Circuits reader wanted a method to indicate when a fan was blowing air. He didn’t want to route any electrical wires to a sensor near the fan. Instead he wanted all the electronics for both the fan and other circuits mounted some distance away from the fan. I scratched my head a bit....

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Telephone Headgear - A compact, inexpensive and low component count telecom headset can be constructed using two readily available transistors and a few other electronic components. Since the circuit draws very little current, it is ideal for parallel operation with electronic Telephone set. (added 4/02)

Telephone in Use LED Indicator - (electronic circuit added 7/03)

Telephone in Use Light - ASCII format (electronic circuit added 7/03)

Telephone In-Use Indicator - Allows to record important telephone conversations. ….(electronic schematic added 11/08)

Telephone In-Use LED Indicator - (electronic circuit added 4/05)

Telephone in-use light - (electronic design added 6/07)

Temperature Indicator - This circuit sets off a buzzer after the last LED (led4) is lit. It is a simple but fun circuit to experiment with. You can replace the buzzer with something else, add a trimpot to adjust sensitivity, etc, etc. The possibilities are endles.....(Tony van Roon's circuits added 08/09)

Three-Level Audio Power Indicator - Battery-operated 3 LED display. Simply connect it to loudspeaker output. (electronic circuit added 06/07/08)

Tripler Converts 5 Volt to 15V - AN-726 Analog Devices Application Note (app note added 6/06)

Ultra Low Power LCD Indicator - (electronic design added 6/07)

Water Level Alarm (Andy Collison) - (electronic design added 9/02)

Water Level Indicator with alarm - This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full. The circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs. When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch.... (added 10/05)

Indicator Circuits: #'s - B C - F G - O P - S T - Z