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Transistor Circuits
Transistors:  #'s - C    D - I     J - O     P - S     T - Z
 

Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :

FET Input High Speed Light Detector -  This circuit is yet another design that converts current from a PIN photo diode to a voltage.  it has a bandwidth that extends beyond 50MHz. . . Circuit by Dave Johnson P.E.-June, 2000

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 Dave Johnson P.E.-July, 2000

Form Push-Pull Driver using N-Ch & P-Ch Transistors  -  This circuit can produce high speed output signals with fast rise and full times.  The unique change pump action allows the voltage of the upper P-ch device to range from millivolts to hundreds of volts.  The output current is only limited by the rating of . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

High Impedance JFET Buffers -  I have used these circuits many times.  They are great when you need a low gain AC signal amplifier with a very high input impedance.  it is good to beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

High Speed Light Detector from FET Input -  This circuit is yet another design that converts current from a PIN photo diode to a voltage.  it has a bandwidth that extends beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Improve Response Time of a Photo Transistor Circuit -  This page shows different ways to improve the response time of a photo transistor circuit . . . Hobby Circuit designed by David Johnson P.E.-November, 2010

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747


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

Designing VCOs & Buffers using the UPA family of Dual Transistors 3/99  -  App Note  Doc #927__ California Eastern Laboratories

Differential EPAD MOSFET Matched-Pair with Buffered & Summed Outputs -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Differential EPAD MOSFET Matched-Pair with Summing Output -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Diode-Connected EPAD MOSFET with Buffer Amplifier Output -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Driving & protecting inverter IGBTs -  EDN Design Ideas:  06/12/2014     A special purpose optocoupler can solve your iGBT gate-drive and fault-feedback needs __ Circuit Design by Avago Tech Note

E-B-C Transistor Pin Identifier -  Tests transistors and diodes for polarity; Simple circuitry - 9V Battery operation __ Contact Flavio Dellepiane, fladello @ tin.it

Equivalent Transistors -  below is a list of equivalent transistors for use in early solid state Quad equipment - particularly the 33 and 303 (Many thanks to Michael Coatham for sending me the data)  __ Designed by quadworld @ reocities.com

FET audio mixer -  This simple circuit mixes two or more channels into one channel (eg.  stereo into mono).  The circuit can mix as many or as few channels as you like and consumes very little power.  The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic.   __ Designed by Aaron Cake

FET based metal Detector using MPF102 / J310 BF998 FETs -  Making a metal detector was always my dream.   I was curious listening to those beeps at airport for which dad explained that they were metal detectors.  Which did not mean anything to me.  Last summer I had opportunity to find secrets behind this little stuff from my dad which turnout to be simple project one can make at home. __ Designed by Nina Gajjar

FET biasing targets battery-powered PWM applications -  11/21/05 EDN Design Ideas:  Reference provide as constant bias voltage regardless of supply-voltage variations __ Circuit Design by Steve Franks, Franks Development LLC, Tucson, AZ

FET Input High Speed Light Detector -  This circuit is yet another design that converts current from a PIN photo diode to a voltage.  it has a bandwidth that extends beyond 50MHz. . . Circuit by Dave Johnson P.E.-June, 2000

FET Oscillators -  This circuit comes from the Progressive Communications Receiver that is in most of the recent ARRL Handbooks and the article "A Progressive Communications Receiver", by Wes Hayward and John Lawson, QST, November 1981, Page 11.   __ Designed by Web David White, WN5Y

The Open Half-Wave Dipole Antenna Project for the FM Transmitters -  I have used this special type dipole antenna with the 200mW FM Transmitter and the 7 Watt.  it has performed very well indeed.  Construction is fairly easy and the whole assembly is light-weight.  if you any questions concerning it or should you decide to make it, give me a call and I will help in any way that I can __ Designed by braincambre500 @ yahoo.com

FET Preamp Cable -  This circuit comes from the Progressive Communications Receiver that is in most of the recent ARRL Handbooks and the article "A Progressive Communications Receiver", by Wes Hayward and John Lawson, QST, November 1981, Page 11.  __ 

The Original Islander using the NTE342 Transistor -  My design of the islander came after one year of intense experimentation.  Formally, the last stage had 3 more variable capacitors.  but I took them out and adjusted their respective coils to a preset form.  thereby eliminating of having to adjust 5 variable capacitors.  My PCB design is a 'no hole' component mount.  The PCB does look rather worn __ Designed by braincambre500 @ yahoo.com

FET Preamplifier -  Field Effect Transistor is an amplifying device in which the output current depends on the input voltage.  The FET Pre Amplifier described here is a sensitive and stable Preamp circuit using an N-Channel FET and a PNP Bipolar transistor.  This combination gives high input impedance and low output impedance with stabilized gain.   __ Designed by D Mohankumar

FET Transistor Homemade from Cadmium Sulfide Photocell -  Homemade FET Transistor Made From Cadmium Sulfide Photoresistor.   __ Designed by Nyle Steiner K7NS

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 Dave Johnson P.E.-July, 2000

Field Effect Transistor as a Voltage Controlled Resistor  -  An FET can be used as a voltage controlled resistor (vcr) where the resistance between the drain and source is controlled by the gate-source voltage, __ 

FM Transmitter -  While there are a plethora of similar 2-transistor schematics available, this one is above average.  A major improvement overlittle 1-transistor circuit that we've discussed previously, this transmitter consist of two stages.  first transistor is used to amplify audio, __ 

FM Transmitter Circuit -  Schematic only, no circuit description is included __ Designed by Kamran Ahmed-UK

Form Push-Pull Driver using N-Ch & P-Ch Transistors  -  This circuit can produce high speed output signals with fast rise and full times.  The unique change pump action allows the voltage of the upper P-ch device to range from millivolts to hundreds of volts.  The output current is only limited by the rating of . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

Four Small Transistor Alarm Circuits -  Battery-Powered Alarm Circuits:  This is a selection of simple self-contained transistor based alarm circuits - complete with photographs.  They are designed around the Complementary Latch.  All may be triggered by both normally-open and normally-closed switches.  They have a very low standby current - and are ideal for battery operation.  __ Designed by Ron J.

Four Transistor Tracking Transmitter -  Schematic and parts list only, no circuit description included.   __ Designed by Tony van Roon  VA3AVR

Four-transistor H-bridge -  an interesting 4-transistor H-bridge variant; this is cheap and easy to build, and best of all is "smokeless" (i.  e.  , no combination of inputs can cause the bridge to self-destruct).   __ Designed by Wilf Rigter

Full Featured Transistor Tester -  Just the thing to check the transistors for any project __ Designed by Rod Elliott  ESP

Fuzz-box -  All-FET design; Valve-like distortion behavior __ Contact Flavio Dellepiane, fladello @ tin.it

Gate-Drive Method Extends Supply's Input Range -  26-Jun-03 EDN Design Ideas:  industrial and telecom applications often require a nonisolated, low-voltage supply from a high-voltage input.  IC manufacturers have responded to that need with the application of high-voltage processes and offer control ICs  that work to 50V and higher.  That voltage is sometimes insufficient, and you need further design techniques to extend the input voltage __ Circuit Design by John Betten and Robert Kollman, Texas Instruments, Dallas, TX

Gate-drive transformer eases multi-output, isolated DC/DC-converter Designs -  04/12/13  EDN Design Ideas:  Use this small transformer to produce four isolated outputs of about 1W each.   Oftentimes the biggest obstacle in designing an isolated dc/dc converter is the transformer design, a prospect that sometimes discourages designers from undertaking an otherwise straightforward design task.  You can take advantage of the characteristics of an off-the-shelf gate-drive transformer and produce four separate isolated dc outputs.  Gate-drive transformers are actually ideal for low-power dc/dc power transfer, because they have already been optimized for a high product of voltage and time (ET, or volt-microsecond, product) as well as for low leakage inductance. __ Circuit Design by Robert Buono

Graphical technique lets you optimally bias bipolar-junction-transistors -  12/18/97  EDN-Design ideas   You can bias a bipolar junction transistor in several ways.  Determining the best method for your application is easy with a graphical technique.   Biasing an active device, such as a bipolar junction transistor (BJT) , requires that you set the dc voltages and currents of the device.  To optimize the desired result, you need various bias values.  For instance, the input de-vice for a low-noise amplifier may have its best noise performance at 50 µA of collector current and a maximum of 5V of collector-to-emitter voltage, whereas later amplifier stages may require 20-mA collector current and 18V collector-to-emitter voltage to generate the necessary ac voltage at the output.  When you determine the desired bias conditions, you also need to make sure they are repeatable--within certain limits--to ensure consistent performance. __ Circuit Design by Lawrence Grover, Southwest Missouri State University

H-BRIDGE Theory & Practice -  A number of web sites talk about H-bridges, they are a topic of great discussion in robotics clubs and they are the bane of many robotics hobbyists.  I periodically chime in on discussions about them, and while not an expert by a long shot I'vebuilt a few over the years.  Further, they were one of my personal stumbling blocks when I was first getting into robotics[Chuck McManis] __ Designed by Chuck McManis

High Current MOSFET  Flip Flop with Debounced Pushbutton -  This circuit was adapted from the "Toggle Switch Debounced Pushbutton" by John Lundgren.  it is useful where the load needs to be switched on from one location and switched off from another.  Any number of momentary (N/O) switches or push buttons can be connected in parallel.  The combination (10K, 10uF and diode) on the left side of the schematic insures the circuit powers up with the load turned off and the NPN transistor conducting.  These components can be omitted if the initial power-on condition is not an issue. __ Designed by Bill Bowden

High Impedance JFET Buffers -  I have used these circuits many times.  They are great when you need a low gain AC signal amplifier with a very high input impedance.  it is good to beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

High Power FM Microphone FM Bug -  My FM Wireless Microphone has been a very popular project with beginners and experienced constructors alike.  it has been used inside guitars and as the basis of a remote control system.   __ Designed by Harry Lythall-SM0VPO

High Power FM Wireless Microphone -  This FM Wireless Microphone has been a very popular project with beginners and experienced constructors alike.  it has been used inside guitars and as the basis of a remote control system.  I do however, receive many requests for a higher powered circuit and better microphone sensitivity.  This High Power FM Wireless Microphone has a better frequency stability, over 1 Km range and is good on microphone sensitivity.  This has been achieved by adding an RF amplifier buffer (with 10dB gain) and an AF preamplifier to boost the modulation a little.__ 

High Speed Light Detector from FET Input -  This circuit is yet another design that converts current from a PIN photo diode to a voltage.  it has a bandwidth that extends beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

High-Impedance FET probe extends RF-spectrum analyzer's usable range -  21-Jul-05 EDN Design Ideas:  Op amp and careful design/construction build high-impedance RF probe __ Circuit Design by Steve Hageman, Windsor, CA

High-side driver feeds IGBTs & MOSFETs -  11/23/00 EDN Design Ideas:  The low- to moderate-power system in Figure 1 provide as the interface between a pulse-width modulator and a high-side iGBT (insulated-gatebipolar-transistor) or MOSFET switch.  You can use it to interface TTL or CMOS circuitry to an H-bridge __ Circuit Design by Carlisle Dolland, Honeywell Engines and Systems, Torrance, CA

High-Speed Buffer Comprises Discrete Transistors -  02/03/11  EDN Design Ideas:  Get high input impedance to minimize circuit loading.  Circuits sometimes need a gain-of-one buffer to lower output impedance and prevent the load from interfering with the previous stage.  For an application involving a 1.5-MHz, low-power transmitter and antenna, a Burr Brown BUF634 buffer IC would work, but a discrete transistor buffer may be more convenient and less expensive than the IC . __ Circuit Design by Lyle Russell Williams, St Charles, MO

IC maintains uniform bias for GaAs MESFETs -  08/22/02 EDN Design Ideas:  The gate-turn-on threshold voltage for GaAs MESFETs (gallium-arsenide metal-semiconductor field-effect transistors] varies considerably from part to part, even within a given lot.  That behavior makes biasing difficult, especially if you want to design the device into a high-volume product.  To overcome this drawback, you can introduce a current sensor that monitors the bias current and provide as __ Circuit Design by Ken Yang, Maxim Integrated Products, Sunnyvale, CA

Improve FET-based gain control -  12/06/01 EDN Design Ideas:  One problemwith standard FET gain-control circuits is increased noise when you use the FET as a part of a resistive attenuator in series with an op amp.  This configuration attenuates the signal before amplification; hence, it requires much higher gain bandwidth and better noise performance from the op amp __ Circuit Design by Ron Mancini, Texas Instruments, rmancini@ti/com

Improve Response Time of a Photo Transistor Circuit -  This page shows different ways to improve the response time of a photo transistor circuit . . . Hobby Circuit designed by David Johnson P.E.-November, 2010

Improved VBE Doubler -  Circuit is a compensated Vbe doubler which operates over a wide current range.   __ Designed by Jim Haggerman, Hagerman Technology LLC

Inrush limiter also provides short-circuit protection -  06/09/05  EDN Design Ideas:  MOSFET keeps inrush currents due to capacitive loads under control __ Circuit Design by Ryan Brownlee, Process Automation Division, Pepperl & Fuchs Inc, Twinsburg, OH

Inverter 12 volt unit Mos-Fet Design -  A Very Reliable, Efficient and Practical Design.  Do Not ask how to Build this for Power ratings over 1000 watts, That is NOT Practical.   __ Designed by G.L. Chemelec

ISFET-sensor bias -  10-Jun-04 EDN Design Ideas:  iSFETs (ion-sensitive field-effect transistors] are useful for measuring the acidity of fluids.  Accurate measurements require that the iSFET's bias conditions (iD and VDS] be held constant while the gate is exposed to the fluid under __ Circuit Design by Brian Harrington, Analog Devices, Wilmington, MA

Isolated MOSFET driver has wide duty-cycle range -  29-Apr-04 EDN Design Ideas:  The main application for the circuit in Figure 1 is for driving power MOSFETs with signals ranging in frequency from 1 Hz to 300 kHz and with duty cycles from 0 to 100%.  You achieve this goal by using a coreless pc-board transformer.  The switching frequency in most power-electronics circuits ranges from a few hertz to a few hundred kilohertz __ Circuit Design by Jesus Doval-Gandoy and Moises Pereira Martinez, ETSI Industriales, Vigo, Spain

Isolation MOSFET-Driver IC Gets Improved Power Efficiency At Lighter Loads -  8-Jan-09 EDN Design Ideas:  An isolation driver with feedback boosts 5V to approximately 13V, reducing power consumption __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Got Designs?
Please eMail
if you want me to link to and/or post your original design.  Thanks.


Transistors:  #'s - C    D - I     J - O     P - S     T - Z

 


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