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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E. :

ELC signal between 200Mhz-400Mhz - If you need a clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz this circuit works fine.  It uses four voltage-controlled capacitors to change the frequency . . . Hobby Circuit designed by Dave Johnson P.E.-March, 1999

 Exciter Circuit-12v Touch Switch - This circuit generates a 20KHz pseudo sine wave signal that can power approximately 50 remote touch activated switch circuits.  This hobby circuit can support a cable length of approximately 2500 feet.  A typical remote switch circuit is also shown as . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

 FETs & Logic Devices Divides Supply Voltage on Charge Pump Efficiently  - This circuit uses a few FETs and logic devices to down convert a DC voltage to about one half its value . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2000

 Flexible Outputs from Square Wave Driver - This circuit can produce an output signal ranging from DC to 100KHz.  It can source a voltage ranging from 1v to 30v.  It can sink a voltage ranging from zero volts to –30v.  It can drive up to 200ma of current and can even be switched to a floating tristate . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2000

 Fluorescent Lamp Night Light Needs Only 1 Watt - If you are tired of replacing small night light lamps, try this circuit.  The line powered circuit uses a long life cold cathode fluorescent lamp.  A simple charge pump technique runs the lamp without any transformer . . . Hobby Circuit designed by David Johnson P.E.-March, 1999

 Fully Isolated 50/60hz Sync Generator - This circuit will produce a single pulse at the zero voltage cross points of the power line voltage.  An opto-coupler provides a very safe 5KV isolation . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2004

 Gated 125Khz Oscillator - This circuit is uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

 Gated Crystal Oscillator with Very Low Power - The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed.  The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

 Generate 0.5v Negative Supply - A while back someone needed a simple way to generate a negative 0.5v supply from a conventional transformer type AC to DC power supply.  The circuit below uses a couple schottky diodes and a filter capacitor to perform the feat . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2011


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

EEE8023af Compliant Power Over Ethernet (Power Over LAN or PoL) Designs -  iEEE Standards based - Power Over Ethernet (POE) solves the age old problem of how to power all those useful LAN based appliances without needing an AC outlet at every point of application.  We all know the nightmare of developing a really neat LAN network only to face the reality of not being able to find readily available power at every node.  iEEE 802.3af solves  __ Designed by Steve Hageman

Efficient DC/DC Converter Provides Two 15A Outputs from a 3.3V Backplane -  DN278 Design Notes__ Linear Technology/Analog Devices

Eight Switcher Powers High-Performance µPs -  04/13/95 EDN Design Ideas:  The circuit in Fig 1  delivers 8A for driving as many as two of today's high-performance, high-speed µPs.  You can also optimize the design for lower current by changing a few components.  Most systems use a low-current 12V bias supply and a poorly regulated high-current 5V to power the logic.  However,  Design by Chester Simpson, National Semiconductor, Santa Clara, CA

ELC signal between 200Mhz-400Mhz -  if you need a clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz this circuit works fine.  it uses four voltage-controlled capacitors to change the frequency . . . Hobby Circuit designed by Dave Johnson P.E.-March, 1999

Electric power Controller -  suitable as dimmer for 100-Volt lamp up to1200W __ Designed by Seiichi Inoue

EP48 12 V 1.44 W Non-Isolated Buck Converter -  This design kit is a non-isolated 12 V, 120 mA power supply utilizing a LNK304.  This power supply is intended as a general purpose evaluation platform for LinkSwitch-TN in a buck converter configuration.  __ 

EP68 3.3 V 2 a DC-DC Power Supply -  This design kit is a 3.3  V / 2 A (6.6 W) DC-DC converter that is based on a DPA423G device.  This design is intended as an evaluation platform for DPA-Switch devices in the low cost surface-mount DiP package.  __ 

EP-71 3.3 V 2 a DC-DC Power Supply -  This design kit is an isolated 3.3  V, 2 A (6.6 W) DC-DC converter utilizing a DPA423G.  This design is intended as an evaluation platform for DPA-Switch devices in the 8-pin DiP, low cost surface-mount package.  __  

EPLD configures wait-state generator -  02/03/97 EDN Design Ideas:  Using a faster microcontroller or microprocessor in an existing application can boost the performance of a system.  Unfortunately, interfacing the faster processor to the much slower existing peripheral ICs is a complex task.  To o Design by Wally Tjanaka, Philips Semiconductors, Sunnyvale, CA

EPR-54 LinkSwitch 2.75 Watt Low Cost Charger/Adapter -  This design kit is a 5.5 V, 500 mA charger/adapter power supply.  The power supply utilizes the LinkSwitch LNK520 device, optimized for bias winding feedback.  The LinkSwitch integrates a 700 V MOSFET, PWM controller, start-up, thermal shut-down, and fault protection circuitry.  __ 

Exciter Circuit-12v Touch Switch -  This circuit generates a 20KHz pseudo sine wave signal that can power approximately 50 remote touch activated switch circuits.  This hobby circuit can support a cable length of approximately 2500 feet.  A typical remote switch circuit is also shown as . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Extend the input range of a low-dropout regulator -  10/17/02  EDN Design Ideas:  Because of process limitations, all ICs have an input-voltage limitation.  This limitation can be cumbersome when you try to step down a high supply voltage to a lower, regulated voltage using a DC/DC converter, such as a linear re Design by Jeff Falin, Texas Instruments, Dallas, TX

FETs & Logic Devices Divides Supply Voltage on Charge Pump Efficiently  -  This circuit uses a few FETs and logic devices to down convert a DC voltage to about one half its value . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2000

Flexible Outputs from Square Wave Driver -  This circuit can produce an output signal ranging from DC to 100KHz.  it can source a voltage ranging from 1v to 30v.  it can sink a voltage ranging from zero volts to –30v.  it can drive up to 200ma of current and can even be switched to a floating tristate . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2000

Fluorescent Lamp Night Light Needs Only 1 Watt -  if you are tired of replacing small night light lamps, try this circuit.  The line powered circuit uses a long life cold cathode fluorescent lamp.  A simple charge pump technique runs the lamp without any transformer . . . Hobby Circuit designed by David Johnson P.E.-March, 1999

Flyback Controller Improves Cross Regulation for Multiple Output Applications -  DN344 Design Notes__ Linear Technology/Analog Devices

Flyback provides isolated power conversion -  01/07/99 EDN Design Ideas:  NOTE:  Mulitple ideas, Scroll to find this one.  A common requirement in telecommunications systems is to convert an unregulated 48V line to an isolated, accurate dc supply voltage.  The circuit in Figure 1 provide as a 5V, 15W output.  The circuit uses a UCC3809 primary-side controller, which can also control other single-ended converters.  The topology uses peak-current-mode control with a fixed-frequency oscillator.  The design is cost-efficient   Page includes several designs. Design by Philip Cooke, Unitrode Corp, Merrimack, NH

Flyback switcher works down to 1.1V, flashes HBLEDs -  EDN Design Ideas:  11/03/2014     Check out this Di if you need voltage step-up from a single cell.   This Design idea shows a way to drive low-power electronic circuits using a single 1.5V cell.  The design is based on a free-running oscillator that drives a flyback transformer to  generate a controllable higher voltage.  it can be used to power analog circuitry, microcontrollers, and any other light loads. Design by R O Ocaya

Flyback Transformer Driver -  This is by far the best project for someone who is already familiar with High Voltage, but wants to take their experiments to the next level: it requires very little previous experience and skills with soldering and identifying components, and there are virtually no adjustments to be made.  The danger is minimal, as fly back transformers are intrinsically low power devices, not capable of outputting lethal currents (due to the hair-thin secondary windings) , and yet it will give a careless experimenter a nasty RF burn if he accidentally touches the HV wire (nothing beats learning from your mistakes).  if you have never experimented with HV before though, I recommend you start off with an electrostatic project.  This circuit is not a toy!  __ Contact Sam Barros

Fully Isolated 50/60hz Sync Generator -  This circuit will produce a single pulse at the zero voltage cross points of the power line voltage.  An opto-coupler provides a very safe 5KV isolation . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2004

Fuse Blown Indicator -  a simple way to see if a fuse has blown without removing it from its holder __ Designed by Andy Collison

Gate Boost Solar Engine -  Voltage-Controlled Solar Engine: The "Gate Boost Solar Engine" is a new (6/2002) Wilf Rigter 1381-based design.  This uses an internal voltage doubler to turn on a FET more efficiently.   __ Designed by Wilf Rigter

Gated 125Khz Oscillator -  This circuit is uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

Gated Crystal Oscillator with Very Low Power -  The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed.  The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

Gel-Cell Charger I -  This high-performance circuit first quickly starts (Tony van Roon's and holds) the charge at 2 amp, but as the voltage rises the current will consequently decrease.  When the current falls below 150mA, the charger automatically switches to a lower 'Float' voltage to prevent overcharging.  At the point that a full charge is reached, Q1 will bias and the LED will light.   __ Designed by Tony van Roon  VA3AVR

Generate 0.5v Negative Supply -  A while back someone needed a simple way to generate a negative 0.5v supply from a conventional transformer type AC to DC power supply.  The circuit below uses a couple schottky diodes and a filter capacitor to perform the feat . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2011

Generating Negative 5 Volts from 9 Volt Battery -  A 555 timer can be used to generate a squarewave to produce a negative voltage relative to the negative battery terminal.  When the timer output at pin 3 goes positive, the series 22 uF capacitor charges through the diode (D1) to about 8 volts.  When the output switches to ground, the 22 uF cap discharges through the second diode (D2) and charges the 100 uF __ Designed by Bill Bowden

Get buck-boost performance from a boost regulator -  07/11/02 EDN Design Ideas:  The SEPiC (single-ended, primary-inductance-converter] topology is generally a good choice for voltage regulators that must produce an on output voltage that falls in the middle of the input-voltage range, such as a 5V output from a 2.7 to 6V input, The topology has some disadvantages, however.  The efficiency of a SEPiC circuit fares worse than that of buck and boost regulators, and SEPiC desig Design by Tom Gross, Linear Technology Corp, Milpitas, CA

Get just enough boost voltage -  27-May-04 EDN Design Ideas:  Adding a current-mirror circuit to a typical boost circuit allows you to select the amount of boost voltage and to ensure a constant difference between the input and the output voltages (Figure 1).  This circuit is useful for high-side-drive applications, in which a simple voltage doubler is unacceptable because of the voltage range of the components involved or where the input voltage can vary Design by Kieran O'Malley, On Semiconductor, East Greenwich, RI

Get More Power with a Boosted Triode -  3-Apr-03 EDN Design Ideas:  Even though 6L6 beam-power tubes have been around for 66 years, they are still quite popular for use in electric-guitar amplifiers, and its cousin, the 6CA7 (EL34) power pentode, is a favorite among audiophiles.  The developers of these tubes designed them for pentode-mode operation, and they deliver maximum audio power in this mode.  On the other hand,  Design by Dave Cuthbert, Boise, ID

Gyrator -  The gyrator principle uses the effect that the value of input capacitance at the base of a transistor is effectively multiplied by the current gain of the transistor.   __ Designed by Andy Collison

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