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Last Updated on: Thursday, April 07, 2016 01:00 PM


Circuits Designed by Dave Johnson, P.E. :

  • 1 Second One Shot Circuit -  This timer circuit draws only 3ua of current, and can be powered by DC supplies ranging from 3v to 15v. The circuit produces accurate pulses whose time can easily be adjusted, based on the R1 x C1 time constant. The time should not change,  . . . [Hobby Circuit designed by David A. Johnson P.E.,  09/02/10]

  • 1.5V Touch Activated Switch -  A single 1. 5v silver oxide button cell powers this complete touch activated switch circuit for 5 years. It features both a normally open and a normally closed set of solid-state switch thermals. It also has an adjustable sensitivity, which can be set for a touch capacitance change as small as 1 picofarad.  . . . [Circuit by David A. Johnson P.E.,  01/18/02]

  • 10 Turn Pot Forms Frequency Readout -  Lets say you are designing a signal generator for a test fixture. To adjust the frequency you would like to use a ten turn pot with a nice dial mechanism attached as a frequency display. However, a display range of 0 to 9. 99 would be impractical since . . . [Hobby Circuit designed by Dave Johnson P.E.,  01/27/08]

  • 120 VAC / 240 VAC Indicator -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . [Hobby Circuit designed by Dave Johnson P.E.,  07/09/06] 

  • 120 VAC Low Voltage Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac.  . . . [Circuit by David Johnson P.E.,  07/11/06] 

  • 120VAC Under Voltage Tester -  Using a cheap 24vac transformer, this circuit can test a product under low 95vac conditions.   With the components show, it has a rating of 250 watts max.  . . . [Circuit by David Johnson P.E.,  07/12/06]

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

$5 junkbox Circuit Determines Phase Sequence  -  04/23/98 EDN Design Idea   Have you ever wondered which way a blower motor is going to turn when you plug it into an or socket, or have you ever inherited task of modifying three-phase wiring in your plant? File contains multiple circuits scroll to find . . .  [by Hugh Adams, Fort Walton Beach, FL]

 

C measures High-frequency signals -  03/02/98 EDN Design Idea   (File contains many circuits, please scroll to find this one)  To measure a high-frequency signal using an 8-bit C, the time period of the measured frequency must be relatively close to the internal clock of the C. For example,. . .  [by Stan D'Souza, Microchip Technology Inc, Chandler, AZ]

 

0-100C Temperature Detector -  Here is a temperature monitoring system capable of remote temperature reading without transmission losses in the conditioning circuit. The IC AD590 (IC4) is used as a temperature transducer. This semiconductor transducer provides a current output proportional to absolute temperature. . . .  [ EFY Enterprises Pvt. Ltd. All rights reserved]

 

0-500MHZ LM3914 RF Power Meter -  RF Measurement has been an expensive work so far the cost f measuring instruments are concerned. Although, the other project, PM2, is hot favorite among radio amateurs for RF Measurement, I wanted something smaller. . .  [Dinesh Gajjar, VU2F0-Circuit Designer]

 

0-50V 2A Bench Power Supply -  I use the lm10 IC because it has a reference voltage and that's useful for dc power supply. With two ICs can take different output voltage and Amperage. This circuit is protected from short circuit. P2 is for controlling the current at the range of 0-2A. Stabilize the output voltage with R4 on negative pin on op-amp and with R2 & P1 on positive pin. . .  [desinger is hamed_iranmehr AT yahoo.com]

 

1 chip detects optical interruptions -  03/01/01  EDN Design Idea   Setting up a light beam and detector to count objects on a conveyer belt, sense security intrusions, or drive a tachometer is simple. However, the task is no longer trivial if you add ambient light or multiple beams, limit optical power, or extend the dis. . .  [by Frederick M Baumgartner, FM Broadcast Services, Parker, CO ]

 

1 Hex-Inverter IC Makes Four Test Gadgets -  07/30/12  EDN Design Idea   This can be a fun project for students and seasoned engineers alike. . .  [by Raju Baddi]

 

1 IC forms inexpensive inductance tester -  08/02/07  EDN Design Idea   A simple Pierce oscillator measures the inductance of a device under test. . .  [by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy]

 

1 Second One Shot Circuit -  This timer circuit draws only 3ua of current, and can be powered by DC supplies ranging from 3v to 15v. The circuit produces accurate pulses whose time can easily be adjusted, based on the R1 x C1 time constant. The time should not change,  . . . [Hobby Circuit designed by David A. Johnson P.E.,  09/02/10]

 

1 switch controls digital potentiometer -  09/19/02  EDN Design Idea   This Design Idea  is an evolution and simplification of another (Figure 1, Reference 1]. Replacing the three inverted-input NOR gates with their logical equivalents, positive-input NAND gates, makes these three gate symbols consistent. . .  [by im Bach, Delphi Delco Electronics Systems, Kokomo, IN]

 

1 wire bus powers water level sensor -  02/15/01  EDN Design Idea   You can use the simple sensor circuit in Figure 1 to remotely monitor the level of liquid water in a vessel such as a swimming pool. The LMC555 sensor oscillator provides an output-signal frequency that is a function of the water level. This signal drives. . .  [by Dale Litwhiler ]

 

1.000 kHz Sine Wave Generator -  ATTINY2313/AT902313/ATMEAG8515/AT908515, etc. . . .  [From Dick Cappels' project pages]

 

1.5v Battery Meter -  Simple but effective way of testing 1.5volt cells. . .  [by P. Townshend - EduTek Ltd]

 

1.5V Touch Activated Switch -  A single 1. 5v silver oxide button cell powers this complete touch activated switch circuit for 5 years. It features both a normally open and a normally closed set of solid-state switch thermals. It also has an adjustable sensitivity, which can be set for a touch capacitance change as small as 1 picofarad.  . . . [Circuit by David A. Johnson P.E.,  01/18/02]

 

10 Amp 13.8 Volt Power Supply -  Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to troubleshoot and repair other power supply units in the shack. It should be noted that there is no real cost advantage to building your own power supply unless you can get a large power transformer and heat sink for a super low price. Of course rolling our own gives us the ability to customize the circuit and make it even more reliable than commercial units. . . .  [by N1HFX]

 

10 Hints for Making Better Network Analyzer Measurements -  Application Note. . .  [Aligent]

 

10 Hz to 16 MHz, DDS based Low frequency scalar network analyzer with PC control -  This demonstration project built on a 16 MHz DDS source and a A and B detectors to make a full stimulus - response network analyzer that can be built by nearly anyone at a fraction of the cost of a commercial unit. This was a very popular project that showed just how much could be done by a determined Homebrewer. . .  [Steve Hageman's Design Resource]

 

10 Practical Tips You Need to KnoW About Power Products 5965-8239E -  Application Note. . .  [Aligent]

 

10 Turn Pot Forms Frequency Readout -  Lets say you are designing a signal generator for a test fixture. To adjust the frequency you would like to use a ten turn pot with a nice dial mechanism attached as a frequency display. However, a display range of 0 to 9. 99 would be impractical since . . . [Hobby Circuit designed by Dave Johnson P.E.,  01/27/08]

 

10Hz-100kHz D.D.S. Function Generator -  The presented project is a function generator for sinusoidal and square signals production. The output frequency covers the range from 10 Hz to 100 KHz with a step of 2 Hz. The waveform synthesis is based on the D. D. S. technique (Direct Digital Synthesis) and the output frequency is selected through a microcomputer with an embedded thumb wheel keyboard.
. . .  [Designed by George Vastianos]

 

10Hz-1300MHz Frequency Meter -  Universal VHF/ UHF frequency meter. . . 

 

12 Volt Battery Backup -  This simpleproject makes a nice companion to power units in cas of power outages, especially caused by severe weather. . .  [electronic design by Lennie Zink]

 

12 Volt Car Battery Meter -  A 10 LED calibrated voltmeter from 11-15 volts, needs no extra battery. . .  [by P. Townshend - EduTek Ltd]

 

12 Volt to 120 Volt Inverter -  Ever needed a low power 120volt AC Power source for your car, van or truck? Well this circuit should do the trick for you. It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to much power. . . .  [Randy Linscott's website]

 

12.5W PWM Heat Source -  The LT2940 measures a high side current and a differential voltage, multiplies them and outputs a current proportional to instantaneous power. Bidirectional high side currents and bipolar voltage differences are correctly handled by the four-quadrant multiplier and push-pull output stage, which allows the LT2940 to indicate . . .  [Linear Technology App Note - , Apr 26th 2010]

 

120 & 240VAC LED Voltage Indicator -  Useful for power lines control. Simple, transformerless circuitry. . .  [Flavio Dellepiane's web site]

 

120 VAC / 240 VAC Indicator -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . [Hobby Circuit designed by Dave Johnson P.E.,  07/09/06]

 

120 VAC Low Voltage Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac.  . . . [Circuit by David Johnson P.E.,  07/11/06]

 

120VAC Under Voltage Tester -  Using a cheap 24vac transformer, this circuit can test a product under low 95vac conditions.   With the components show, it has a rating of 250 watts max.  . . . [Circuit by David Johnson P.E.,  07/12/06]

 

120W Supply Monitor Includes ICC of LT2940 -  The LT2940 measures a high side current and a differential voltage, multiplies them and outputs a current proportional to instantaneous power. Bidirectional high side currents and bipolar voltage differences are correctly handled by the four-quadrant multiplier and push-pull output stage, which allows the LT2940 to indicate. . .  [Linear Technology App Note - , Apr 26th 2010]

 

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Tester or Measurement (Instrument) Circuits
Test Equipment:  #'s        A-B       C-D        E-G       
H-L       M-O        P-R       S-T       U-Z


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


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