spool.in 4QD-TEC: Electronics Circuits Reference Archive Index
Advertise here
LogoTM

4QD-TEC
Circuits Archive

4QD-TEC: Electronics Circuits Reference Archive
Welcome to 4QD-TEC - 'The Electronics Club'

Index for this page.

This page contains the main index to the electronics section of this site, with certain other general information which you may need.

4QD - The Electronics Club

This site, large though it is, is only the public 'front end' of a subscription electronics club - 4QD-TEC.

For more information and how to join, use the 'Join' button at head or foot of any free page.

Introduction

You will need images on for this area of the site - to see the circuit diagrams (PNG or GIF).

As these pages of circuits (a lot more at the bottom of this one) are proving to be of interest to browsers we are gradually expanding them to give a larger selection of interesting and, perhaps, useful circuits as well as a lot of various information. We want to make our site interesting and useful - not pretty and impressive. Hopefully some of you, one day, may need a PWM motor controller and will remember us!

I know a lot of visitors are coming straight to this index rather than to our Home page. You are welcome - but there are pointers on the home page to other info which is not circuit diagrams. There will be links to other sites, info on manufacturers and suppliers of goods related to our business as well as information on computing and electronics and maybe other subjects. Who knows what else! The author has written for computer magazines, DIY magazines and others.

4QD sell motor controllers: we do not sell web technology. Therefore you won't find animated GIFs, Java Applets or advice to use one particular browser: our pages should work with any browser that can display GIFs and JPEGs. There will be added, in time, one or two JavaScript calculators however.

Transistors or ICs?


Some readers may think I don't like ICs. Not true: it's horses for courses. However it is very often simpler to use three or four transistors than to find that special IC. Many's the time I have spent days looking for an IC to do what I require, only to solve the problem in a few hours when I started thinking discrete. Also - if you use discretes you get a much better understanding of electronics than by using an IC - which to a lot of users may as well be a black box full of magic spells!

Educational Resource

All of which the above makes this site a very good educational resource, and it is evident from the comments we get that it is being used as such. So we intend to expand this area - partially in an attempt to make the site commercially viable. We intend therefore to make circuit board designs available for some of the projects and educational establishments that require reasonable quantities (25 or more) are welcome to contact 4QD to discuss their requirements. We will be able to supply circuit boards for some of the interesting circuits, with kits of parts and assembly information. We can clearly link the boards and kits to constructional information on this site, or we can supply printed out information.

I have however tried to make this site easy to read, so the descriptions aren't too simple or full of maths. Maybe you want this altered - let me know.

Problems and queries.


If you find our site interesting, or if your browser can't cope with it, or even if you think the ideas are silly, please contact the author to discuss them. Maybe also you want more description of how the circuits work, maybe less? I have a wealth of simple, unusual and often original circuits, mostly using a few transistors connected in ways that will surprise you. I also have op-amp, comparator, logic, audio and a lot of other circuits which I have collected or designed because they interest me: maybe they will interest you as well.

Future Plans

The public area of 4QD-TEC is large: future expansion will be in the private area, which is only available to members. This data includes much on PWM motor control (as you might expect) but also lots of other information, including more detailed circuit descriptions and constructional information.

Copyright

4QD manufacture electronic motor speed controls for battery motors. We make our living by selling some of our circuits. Obviously I'm not going to publish commercially sensitive circuits! However a lot of the ones I publish are original and although you are free to use them for your own entertainment, the author retains intellectual property rights to them insofar as they may have commercial value. If you do find them commercially useful, then please contact me for permission to use them. Under no circumstances may they be published in any form without written permission from the author.

Disclaimer

These circuits are supplied 'as is' at no charge, for your enjoyment. So far as we are aware they are complete and work but we can take no responsibility for any errors. We will of course offer any reasonable assistance if you do hit problems. Most, but not all, of the circuits are our own design. As far as we are aware no copyright other that the author's exists on any of them but we cannot guarantee this.

Site Index

The list below is not as long as it looks because it sometimes contains many entries to the same circuit. If so, this is because the circuit has many uses or can be called different things (besides - it makes the list longer!)

Key: Left hand Column

Some of these items are public. Some are members only. Some have a public 'front' but more is available to members. So the left hand column is a key to what is what.
MOInformation is Members Only. You will be asked for a pasword.
MLInformation is Members Only. These are 'Library' collections of circuits with no write-up.
You will be asked for a pasword.
PAPublic area information.
PMPublic area information, with more information available to members.

The index is one long list of all available circuits in alphabetical order. It is however divided into the following areas:

Index Contents

Audio Circuits
Automobile Circuits
Battery Monitoring circuits
Beginner's articles
Circuit Theory and tutorials
Component types and values
Components
Computing
Current sensing and control
Guitar Effects Circuits
LED Control circuits
Industrial Control circuits and suggestions
Measurement Circuits
Motor Control Circuits
Multivibrators
Oscillator Circuits
Power Supply circuits
Pulse (Width and position) Modulation Circuits
Relay Driver Circuits
Staircase generators
Switch Circuits
Test Equipment circuits
Temperature Measurement
Timer Circuits
Ultrasonic Circuits
Voltage/Current controlled circuits

Alphabetical Index

MLAnalogue circuits, Various
PAAnalogue 'counter'
PAAnalogue difference detector
PAAnalogue isolator
PAAstable Multivibrators
Audio Circuits
PAAmplifier, very low THD
MOSinclair circuits and other Sinclair info
PAGraphic Equaliser
PAPreamplifiers
PALED VU meter
PALED VU meter
PAPeak program indicator, speaker powered
MLVarious Audio circuits
Automobile Circuits
MLVarious Auto circuits
PAAutomotive Trafficator Circuit
PATacho and Dwell Meter
Battery Monitoring circuits
MOBattery Condition Metersthe circuits of 4QD's own BCM.
PABattery discharger
PABattery low indicator
MLVarious Battery circuits
Beginner's articlesA selection of articles written for those new to electronics
PAElectricity - an analogy with water
PAHow pwm works
MABistable Latch
PABridge, Full. For motor control
MOBridge, Full. Switching of
SMBridge, Half. For motor control
MOBridge, Half.Current and voltage commutation waveforms
PACharge pump. Cup and bucket
Circuit Theory and tutorials
PAColour codes and multipliersfor resistors and capacitors
PACurrent sources and mirrors
PAElectricity - an analogy with water(good start for beginners)
MOEmitter Coupled Multivibrators
MLFilter CircuitsSingle transistor Gyrator, Multi-feedback, Twin T
PALogic circuits using discretes
PAMiceHow your computer mouse works
PAOp-amp circuitsusing discrete transistors
PATwo transistor regulator circuits
MLVarious Circuit Configurations
Components
PAReed switchesHow to use them
Component types and values
PAColour codes and multipliersfor resistors and capacitors
PATesting MOSFETs
PAComparator with controlled hysteresis
PAComponent values and colour code
MLConverter circuitsD to A, V to Time
PACup and bucket charge pump
Computing
PAPossible bug in Wireless Router adaptive learning?
Current sensing and control
PACurrent Controlled Amplifier
PACurrent loop interface
MLCurrent Monitoring Circuits
PACurrent sensing relay driver
PACurrent sources and mirrorsa 'lecture'
PACurrent source, Switching
PAData switch and indicator, bi-directional
MLDiscrete transistor CircuitsOp Amps, Logic
MLDriver CircuitsTotempole drivers
PADomestic heating control circuit
PAElectric Field detector
PAElectricity - an analogy with water(good start for beginners)
MLFollower Circuits
PAFull bridge for motor control
PAGame circuits
PAGraphic Equaliser
Guitar Effects Circuits
PAPhaser
PAGyrator - used in graphic equaliser
PAH Bridge Switch. For small motors
PMHall effect Current sensing
PA'Jeopardy' circuit
Industrial Control circuits and suggestions
PAAnalogue 'counter'
PAAnalogue isolator
PMBistable Latch
PACoil catching diodesAKA flywheel diodes. Why they are needed.
PACurrent loop interface
PACurrent sensing relay driver
PAH Bridge Switch. For small motors
PMIndustrial process control circuits
PAImpulse relay circuitPulse to set, pulse to reset
PMModular industrial relay systemBase relay allows timers etc to be added
PAOpto isolator, Analogue
PMRelay driver, transistorised
PAStepper motor, clock oscillator
PASwitch, Impulse changeover
PASwitching Solenoid Driver
PMTimer circuits
PAImpulse changeover Switch
PMIndustrial process control circuits
PAIntercom with speaker as microphone
PAJoystick Interfaces
MOLab Power supply0-50 volts, 0-5 amps or whatever you decide.
MLLamp and Bulb drivers
PALatch, Data bi-directional
PALeakage detector
LED Control circuits
MLLED Driver Circuits
MOLED Volt Meters4QD's 3, 5 and 7 LED voltmeters, circuits, partslist, descriptions
PALED VU meter
PALED brightness control circuits
PALogic circuits using discretes
MLLogic CircuitsLatches. Transparent data, R-S etc.
PAMains Wiring detector
MLMathematical AnalysesOne TUN gyrator
PAMiceHow your computer mouse works
PAMicrophone preamplifiers
PAModulators, Pulse Width
PMMOSFET current sensing
PAMOSFET testing
Measurement Circuits
PMHall effect Current sensing
MOLED Volt Meters4QD's 3, 5 and 7 LED voltmeters, circuits, partslist, descriptions
PALED VU meter
PATesting MOSFETsUse a multimeter to test a MOSFET
MLPeak Detecting Circuits
MOVoltage breakdown testerfor transistors and diodes etc
Motor Control Circuits
PAAnalogue isolator
PMBattery Current Limiting
PABridge, Full. For motor control
PAPart 1Bridge, Half. For motor controlA discussion
MOPart 2PWM motor speed control Deals with early 2QD circuits
MOPart 3PWM motor speed control Development of 2QD series
MOPart 4PWM motor speed control Modern 2QD series. Detailed discussion
MOPart 5PWM motor speed control Ramping and reversing. NCC series controllers
MOPart 6PWM motor speed control Waveforms and commutation in a MOSFET half bridge
MOPart 7PWM motor speed control MOSFET full bridge switching using two half bridges
MOPart 8PWM motor speed control MOSFET full bridge switching - Fully complementary
MOPWM motor speed control Part 7Starts to deal with Full bridge control
PMConstant Power throttle How do simply incorporate constant power throttle
PAH Bridge Switch. For small motors
PMMOSFET current sensing
PAPulse Width modulators
MLPulse Width modulatorsSeveral circuits
PMPWM motor controlMany more articles, including constructional information and theory.
PATacho generator amplifierAs used in 4QD's Tacho feedback board
PAMultipliers (3n3 etc) for resistors and capacitors
Multivibrators
PAMultivibrators
MOMultivibrator, emitter coupledLinear ramps, good waveform
MOTest ramp generator, for power device testingA practical application of the emitter coupled multivibrator
MLMultivibrator circuitsAstables. Bistables, Ring Astables
PAOp-amp circuits using discrete transistors
PAOpto isolator, Analogue
Oscillator Circuits
MOMultivibrator, emitter coupledLinear ramps, good waveform
PAQuadrature (sine/cosine)voltage controlled, quasi-sinusoids
PAThree phase
PAVoltage controlledprogrammable, wide range.
PARelaxation oscillators multivibrators
PAWien Bridge
MLOscillatorsMultivibs, Ramp generators, Sawtooth,
Sinewave, Sounders, VCOs, Waveform Generators
MLPeak Detecting Circuits
PAPerson detector
PAPhaser for audio/guitar effects
Power Supply circuits
PMPower supplies with enable and automatic switchoff
PAPower supplytripped, regulated, high current
MOPower supplyRe-entrant, regulated, high Current
MOPower supply, Lab type0-50 volts, 0-5 amps or whatever you decide.
MLPower Supply CircuitsVarious
PATwo transistor regulator circuitsa theoretical discussion
PAPreamplifiers, audio
PAPreamplifiers, ultrasonic
PAProgrammable Unijunction Transistor
PAPrecision rectifier circuitin tacho amplifier
PAPrecision rectifier circuitin Joystick interface
Pulse (Width and position) Modulation Circuits
PAPulse Width modulators
MLPulse Width Modulators
PAPulse Width Position Servo control
PAPWM motor control - part one of a serieslinks to much more in member's area
MO2QD controllerCircuit diagram, component list, PCB layout
MLPulse Processing Circuits
PAPulse width comparator
PAPulse width to voltage converter
PAPump and hold (staircase)
PAPUT pair2 Tr equivalent to SCRs, SCSs and other 4 layer devices
PAPWM motor control
PAQuadrature (sine/cosine) oscillatorvoltage controlled
PARadio Control Interface
PARamp generator(separate + & - ramps)
MLRamp CircuitsRamping and Slew Rate control
PARelaxation oscillators
Relay Driver Circuits
PAImpulse relay circuitPulse to set, pulse to reset
PMLatching, transistorised
PMRelay driver, transistorised
PARelay logic: Startt/Stop buttons
PASwitching Solenoid Driver
PADrive two relays via one wire
MLRelay Driver Circuits
PAResistor colour code
MLRotary Encoder Circuits
PARobot wars: start here!
PASchmitt Trigger: an unusual circuit
PASinewave Generator
Staircase generators
PAStaircase generator
PAStaircase generator
MLStaircase Generators
PAStepper motor used as encoder
PAStepper motor, clock oscillator
Switch Circuits
MLToggle action switches
MLData Switches
MLTouch operated Switches
PASwitch, Impulse changeover
PASwitch, Touch operated
PASwitching Solenoid Driver
PATacho generator feedback circuit
Test Equipment circuits
MOLab Power supply0-50 volts, 0-5 amps or whatever you decide.
MOVoltage breakdown testerfor transistors and diodes etc
MOTest Ramp generatorFor Power device curve tracing
MLSemiconductor TestersJFET offset voltage tester, Diode Vf tester
Beta Meter, Bipolar polarity checker
Temperature Measurement
PAThermometer and thermostat for Room temperatures
PAThermostat
MLThermostat circuits
Timer Circuits
PMTimer: delay on de-energise
PMTimer: delay on energise
PMTimer: pulse output
PATouch operated Switches
PATwin-T oscillator
PATwin-T tuned Ultrasonic Preamp
Ultrasonic Circuits
PAUltrasonic Intruder detector
PAUltrasonic Preamp with AGC
PAUltrasonic Preamp with Twin-T tuning
PAUltrasonic Receiver
PAUltrasonic Transmitter
PAUnderstanding Electricity - an analogy with water
MOLED Volt Meters4QD's 3, 5 and 7 LED voltmeters, circuits, partslist, descriptions
MOVoltage breakdown tester for transistors
MOVoltage breakdown tester circuits
Voltage/Current controlled circuits
PACurrent Controlled Amplifier
PAOscillator, Quadrature (sine/cosine)
PAOscillator - multivibrator type
PAOscillator, programmable, wide range
MLVoltage and Current controlled amps
PAVU LED meter
PAWaveform generator circuits
PAWien Bridge oscillator
MLWindow Detectors


Page Information


© 1997-2014 4QD-TEC
First published:
Page's Author: Richard Torrens
Site hosted by Arachsys