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Circuits designed by David Johnson, P.E.
Last Updated on: Thursday, April 07, 2016 02:04 PM

Master Category List - Dave's Circuits

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Data Logging / Acquisition Circuits

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


Audio Frequency Digital Noise Generator  -  When you need to test an audio circuit with broadband noise, this circuit works great. It uses just three inexpensive C-MOS ICs that generate a series of output pulses whose widths vary randomly. I included a level control pot . . . [Circuit by David A. Johnson P.E.,  07/04/00]


Characteristics of CMOS Logic Inverter Amplifiers  -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage Amplifiers . . . [Hobby Circuit designed by David A. Johnson P.E.,  02/11/02]

Circuit Forms Divide By 1.5 Counter  -  Two inexpensive ICs divide a TTL clock signal by 1.5. By following the circuit with another flip/flop, you could also generate a divide by three function . . . [Circuit by David Johnson P.E.,  07/06/00]


CMOS Logic Inverter Amplifier Characteristics  -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage Amplifiers . . . [Circuit by David A. Johnson P.E.,  02/11/02]


Digital noise generator  -  When you need to test an audio circuit with broadband noise, this circuit works great. It uses just three inexpensive C-MOS ICs that generate a series of output pulses whose widths vary randomly. I included a level control pot . . . [Hobby Circuit designed by Dave Johnson P.E.,  07/04/00]


Divide a TTL Clock Signal by 1.5  -  Two inexpensive ICs divide a TTL clock signal by 1.5. By following the circuit with another flip/flop, you could also generate a divide by three function . . . [Hobby Circuit designed by David Johnson P.E.,  07/06/00]


Divide By 1.5 Counter  -  Two inexpensive ICs divide a TTL clock signal by 1.5. By following the circuit with another flip/flop, you could also generate a divide by three function . . . [Circuit by David A. Johnson P.E.,  07/06/00]


Does Power Line have 120 VAC or 240 VAC?  -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . [Circuit by Dave Johnson P.E.,  07/09/06]


DVD Recorder + TV Camera Make Cheap Data Logger  -  Sometimes recording the results of a test requires as much ingenuity as designing the product. Consider a situation which requires the collection of many different variables over a long period of time . . . [Hobby Circuit designed by David Johnson P.E.,  04/01/05]


Honeybee Counter  -  I designed a circuit similar to this one a long time ago to help a beekeeper count the number of bees going into or out of a hive. The low power circuit uses a slotted opto-sensor to detect the passing bees. The circuit advances an electronic counting . . . [Circuit by Dave Johnson P.E.,  07/08/00]


Indicates 120 VAC or 240 VAC  -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . [Hobby Circuit designed by David A. Johnson P.E.,  01/07/07]


Indicates either 120 VAC or 240 VAC   -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . [Circuit by David A. Johnson P.E.,  07/09/06]


Slotted Opto-Sensor used in Honeybee Counter  -  I designed a circuit similar to this one a long time ago to help a beekeeper count the number of bees going into or out of a hive. The low power circuit uses a slotted opto-sensor to detect the passing bees. The circuit advances an electronic counting . . . [Hobby Circuit designed by David Johnson P.E.,  07/08/00]


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