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All Material © 1998-2024 Rod Elliott (ESP)
Copyright For Each Individual Article Is Shown At The End Of Each Page
Page Last Updated - September 2024

Articles are sorted alphabetically within categories (also in alphabetical order).  All projects are in numerical order.

Indexes

Main Index
Articles Index
Projects Index

Articles
555 Timer Applications
6dB Speaker Crossovers
Active Filters
Active Vs. Passive Crossovers
A-B Blind Comparator
ABX Test Set
Acoustic Feedback & Frequency Shifting
Active Filters Using Gyrators
AM Radio - Wideband/ Hi-Fi
Amplitude Modulation For Simulations
Amplifier Basics - Intro
Amplifier Basics - Part 1
Amplifier Basics - Part 2
Amplifier Basics - Part 3
Amplifier Basics - Part 4
Amplifier Basics - Part 5
Amplifier Basics - Part 6
Amplifier Bridging
Amplifier Classes - Class-A, Class-B, etc.
Amplifier Design
Amplifier Efficiency
Amplifier Power - How much do you need
Amplifier Troubleshooting
Amplifier Troubleshooting - Part 2
Amplifier Protection
Amplifier Sound
Arc Prevention For Switching Circuits
Analogue Vs. Digital
A-Weighting (and why it's wrong)

Baffle Step EQ
Balanced Circuits
Balanced Circuits Part II
Balanced Circuits Part III
Balanced Circuits Part IV
Beginners Guide to Components
Bi-Amplification (Part I)
Bi-Amplification (Part II)
BJT Parameters
Bleeder Resistors in PSUs
Bootstrap Circuits
Bucking Transformers
Bulletin Boards
Buying Electronic Components

Cables - Part 1
Cables - Part 2
Cables - Part 3
Cables - Part 4
Cables - Part 5
Cables - Part 6
Cable Impedance
Cable Information
Capacitors in Depth
Capacitor Coupling In Output Stages
Capacitance Multipliers
Commercial Sound (70-100V Lines)
Compound (Sziklai) Vs. Darlington pairs
Comparators - The Unsung Heroes Of Electronics
Coupling Capacitors
COAX - Introduction To Coaxial Cables
Current Drive Power Amps & Effects on Speaker Drivers
CD Vs. SACD Vs. DVDA
Class-A Amplifiers
Class-A Amplifiers - Part 2
Class-D Amplifier Theory & Design
Class-D Amplifiers (Part II)
Class-G Amplifiers
Compliance Scaling Loudspeakers

Compression in Audio
Counterfeit Transistors
Crossover Distortion
CFB Vs. VFB (Current Vs Voltage Feedback)
Current Monitors - Detection & Measurement
Current Sources, Sinks & Mirrors

Dangerous Power Supplies
DC Servos - Tips, Traps & Applications
Derived (Subtractive) Crossover Networks
Designing with Opamps - Part 1
Designing with Opamps - Part 2
Designing with Opamps - Part 3
Distortion & Negative Feedback
Distortion - What It Is, How It's Measured
Doppler distortion in Loudspeakers
DSP - Digital Signal Processing in Audio

Earthing (Grounding) Techniques
Electret Microphones, Powering & Uses
Electronics Tools
Electrocution & How To Avoid It
Electret Microphones
Electronic Fuses
Equalisation & How It Works
ESD Protection
Essential Formulae For Electronics
External Power Supplies - New Regulations

FET Applications
FET Circuit Design Process
Followers & Buffers, Various Techniques Examined
Frequency, Amplitude and dB
Fusing & Circuit Protection

Glossary of Terms
Guitar Amps - Repair or Replace
Guitar Speakers - Getting 'the sound'
Guitar Pickup Voltages

Heatsinks
Heatsinks - Selection For Amplifiers
Heatsinks - DIY
HEXFET Audio Amplifiers
High Speed Opamps
Hybrid Relays

IC Power Amplifiers - more power by adding transistors
Impedance
Impedance Compensation for Loudspeakers
Impedance Effects
Inductor/ Capacitor Oscillators
Instrument Amplifiers
Intermodulation Distortion - sum & difference frequencies
Intermodulation Distortion - measurement techniques & effects
Incandescent Lamp Ban
Inrush Current Mitigation
Introduction to Potentiometers
Inrush Current Testing
Inverters - different types explained

JLL Hood Class-A Amp
Linkwitz Transform
LDO (Low Dropout) Voltage Regulators
Lithium Cell Charging & Battery Management
LM358/ LM324 Opamp Distortion Reduction
Lock-In Amplifiers
Logic - A Beginners Guide
Loudspeaker Crossover Design Tables
Loudspeaker Acoustic Centre Offset
Loudspeaker Enclosure Design Guidelines
Loudspeaker L-Pad Calculations
Loudspeaker Power vs. Efficiency

Mains Power Quality
Mains Safety (Essential Reading)
Mathematical Functions Using Analogue Circuits
Meter Attenuators
Meters, Multipliers & Shunts
Microphones
Microphones (Part II)
Microphone Signal Splitters
Miscellaneous Components
Mixing Principles, Active & Passive
MOSFET Relays
Morse Code
Motors - AC and DC
Multimeters - Analogue & Digital
Myths in Audio

Negative Impedance
Neville Thiele Method (NTM™) Crossovers
Noise in Audio Circuits
Notch Filters

Off-Line Flyback Power Supplies
Opamp Alternative Circuits
Opamp History
Opamps - Frequency Vs. Gain & Slew Rate
Oscilloscopes. How They Work And Usage
Over-Voltage Protection

Power Supply Design Index
Passive Crossovers
Patents - General Information
Passive Line Level Crossovers
Phantom Power - What It Is And How It Works
Phase Angle Vs. Transistor Dissipation
Phase Correction - Myth or Magic?
Phase, Time & Distortion
Phone Plugs and Sockets
Power Amplifier Clipping Behaviour
Power Amplifier Development Over The Years
Power Ratings
Power Supply Design
Power Supply Simulation
Power Supply Snubbers
Power Supply Snubbers II
Power Supply Design (Part II)
Pre-Regulators
Projects, DIY & Sustainability

Rectifiers - Selection & Usage
Relays - Part 1
Relays - Part 2
Relays - Part 3
Reverberation Tanks
Review of BE Valve Amplifier

Satellites & Subs (QB5 Alignment)
Safe Operating Area (SOA)
Sinewave Oscillators - Characteristics, Topologies, Examples
Servos - Hobby Servos, ESCs And Tachometers
(The) Subwoofer Conundrum
Series vs. Parallel Crossovers
Small Power Supplies (Part I) - Low Current, Including 'Off-Line'
Small Power Supplies (Part 1I) - Transient Response & Noise
Small Satellite Speaker (Part 1)
Small Satellite Speaker (Part 2)
Small Satellite Speaker (Part 3)
Soft Clipping Circuits
Soft Start Circuits
Solid State Relays
Sound Impairment Monitor
Sound - Illusion?
State Variable Filters
Speaker Failure
Squarewave Testing Amps & Filters
State of Manufacture
Switchmode Power Supplies (Part II)
Switch De-Bounce Techniques

Transistor Matching
Transistor listing
Transformers and mains DC offset
Transformers - Part 1
Transformers - Part 2
Transformers - Part 3
Transformers - Part 4
Transformers - The Variac
Transformers for 'Line Level' Audio
Transformerless PSUs
Thermistor Selection
Thiele-Small Parameters
Time Alignment With Phase Shift Networks Triamped Speaker System - Part 1
Triamped Speaker System - Part 2

Voltage Dividers & Attenuators
Volume Filling Reflex Enclosures

What Makes Tweeters Blow
What Is Hi-Fi
Why Do It Yourself?
Wiring A Power Supply
Waveguides, Part 1
Waveguides, Part 2
Waveguides, Part 3

Yellow Glue


Valves
Valve Articles Index
Valve Amps - Do they really sound different?
Valve intro - types, terminology, etc.
Bias and Gain
Valve Stage Analysis
Design Considerations - Part 1
Design Considerations - Part 2
Low Distortion Preamps
Valve Myths
High Voltage DC Supply
High Voltage Time Delay


Application Notes
Application Notes Index
Precision Rectifiers
Analogue Metering Amplifiers
High Power Led SMPS
Car Dome Light Extender
Zero Crossing Detectors
Ultra-Simple SMPS
Transistor Assisted Zener
Using Zener Diodes
DC Motor Speed Controller
DC Motor Speed Controller (II)
2-Wire/4-Wire Converters
4-20mA Current Loop Interfaces
Peak, Average and RMS Measurements
Reverse Polarity Protection
Peak Detection Circuits
Input Overvoltage Protection
Measuring Ultra-High Resistance
DC Detectors For Loudspeaker Protection
Ultra-Low Leakage Diodes
'Zero Power' LED battery Indicator
Mains Peak Voltage Detectors


Purchases
Ordering Info
Price List
Fully Built Modules
Guitar Amp Module
Digital Flash Module
VP-103 Valve Preamp
PayPal Details
Western Union Details
Dead Letters


Clocks
Clock Components
Clock Motors
Kundo Battery Clocks
Old Synchronous Motors
Frequency Changer
Build a Synchronous Clock
Free Pendulum Clock
1.5V Mains Supply
Magnet Charger
Simple Flux Meter
Spark Quench Circuits
1 second timebase
Fast Demagnetiser
Arduino Based Slave Clock Driver



Gallery
Gallery Index
L-R Crossover (2)
Reader Feedback - Part 1
Reader Feedback - Part 2


Downloads
Crossover Calculator (EXE)
Download Index
Heatsink Calculator (ZIP)
Heatsink Design (XLS)
LED LM3915 VU Design (ZIP)
MFB Filter Calculator (EXE)
Loudspeaker Parameters (ZIP)
Crossover Design (ZIP)
Linkwitz Transform Design (ZIP)
PC Timer Program (EXE)
Reminder Program (EXE)
Semiconductor Data (EXE)
Serial/ Parallel Resistor Calc. (ZIP)
Transformer analysis program (ZIP)
Transformer analysis spreadsheet (ZIP)
Transformer design program (ZIP)


Humour
Humour Index
Humour - Part 1
Humour - Part 2
Murphy's Laws
A Space Oddity
If Your O/S Were an Airline
Waltzing Matilda Explained
Monty Python
Dynamic Range Vs. Ambient Noise
Satcure Products


Miscellaneous
Hall of Shame
Home Page
Main Index
Main Links Page
Mad As Hell - Part 1
Mad As Hell - Part 2
Mad As Hell - Part 3
Mad As Hell - Part 4
ESP Ethics Policy
About ESP Site
Contact the Author
Submit Your Material
Contracting Details
About the Author
Custom Projects for Education
Frequently Asked Questions
Spam, Scams & Security
Scams - how they work
Your on-line security
Spam, Spam, Spam, Spam
Disclaimer
Search Page
Contribute Project/ Article
Project Cost Estimates




TCAAS (The Class-A Amplifier Site)
The JLH Class-A Amplifier
Other JLH Amplifier Designs
Other Class-A Amplifiers
Classic Class-B Schematics
JLH Power Amp Schematics
The Published Articles of John Linsley Hood
Lamps, PSUs, Energy
Lamps - Incandescent, etc.
Capacitance, Inductance & Non-Linear Loads
Dimmers
Dimmers - Part 2
Dimmers With LED Lighting
Electronic Transformers
ESL (Electron Stimulated Luminescence) Lamps
External Power Supplies
Fluorescent Lamps
Induction Fluorescent Lamps
Inrush Current Protection
LED Lighting
LED Lighting - Thermal Design
Sulphur Plasma Lamps
Power Calculations - Watts, VA (AC or DC)
Power Factor Correction
Power Saver Scam
Wind Turbine Introduction
Wind Turbine Noise


Projects
Projects Index
Projects Index by Category
Project List in Numerical Order

00   Opamp Bypassing
01   Better Volume Control
02   Simple Preamp
02   60W Power Amp
04   Power Amp Supply
05   Preamp Power Supply
05A Updated Preamp Power Supply
05-Mini   Budget Preamp Power Supply
06   Phono Preamp
07   Discrete Opamp
08   3rd Order Electronic Crossover
09   Linkwitz-Riley Crossover

10   Class-A Amplifier
11   Pink Noise Generator
12   Current Feedback Power Amp
12A El-Cheapo Power Amp
13   Low Noise Preamp
14   Power Amp Bridging
15   Capacitance Multiplier
16   Audio Millivoltmeter
17   A-Weighting Filter
18   Surround Decoder
19   50W IC Power Amp

20   Simple Bridge Adaptor
21   Stereo Width Controllers
22   Audio Oscillator
23   Clipping Indicator
24   Headphone Amplifier
25   Phono Preamps For All
26   Digital Delay
26A PT2399 Digital Delay
27   Guitar Amp (Original)
27   Guitar Amp (Part 1)
27   Guitar Amp (Part 2)
28   Quasi-Parametric EQ
29   Tremolo Unit

30   Mixing Desk (Part 1)
30   Mixing Desk (Part 2)
30   Mixing Desk (Part 3)
30   Mixing Desk (Part 4)
30   Mixing Desk (Part 5)
31   Transistor Tester
32   Car Audio Preamp
33   Speaker Protection and Mute
34   Spring Reverb Unit
35   Direct Injection Box
36   DoZ Class-A Amplifier
37   DoZ Preamp
38   Auto Power-On
39   Soft Start Power Switch
3A   60W Hi-Fi Power Amp
3B   25W Class-A Power Amp

40   Load Sensing Auto Switch
41   Opamp Design & Test Board
42   Thermo-Fan Controller
43   Simple DC Split Supply
44   Dual Lab Supply
45   Bass Compressor
46   Thermal Shutdown
47   VOX AC30 Simulator (withdrawn)
48   Sub Equaliser
49   Guitar Vibrato

50   Mic Circuit Tester
51   Balanced Line Drivers
52   Distortion Analyser
53   Power Limiter
54   Low Power FM Transmitter
55   PPM and VU Meters
56   Variable Amp Impedance
57   Sound Impairment Monitor
57   Speaker Measurement Set
59   Self Oscillating Amp

60   LED VU Meter
61   (Withdrawn)
62   Lighting System (Part 1)
62   Lighting System (Part 2)
62   Lighting System (Part 3)
62   Lighting System (Part 4)
62   Lighting System (Part 5)
62   Lighting System (Part 6)
63   MFB Filter
64   Instrument Graphic EQ
65   Strobe Light
66   Balanced Mic Preamp
67   Audio Peak Limiter
68   Sub Power Amp
69   Low power +/-12V supply

70   DoZ Headphone Amp
71   Linkwitz Transform Circuit
72   20W IC Stereo Amp
73   PC Sound System
74   RF Probe
75   Constant Q Graphic EQ
76   Opamp Based Power Amp
77   High Current 13,8V Supply
78   2nd Order Electronic Crossover
79   Current Sense Power Switch

80   Reverse RIAA Equaliser
81   12dB L-R Crossover
82   Loudspeaker Test Box
83   MOSFET Follower Amplifier
84   1/3 Octave Sub Equaliser
85   S/PDIF DAC
86   Mini Audio Oscillator
87   Balanced Transmitters & Receivers
88   Audio Preamp
89   Car Switchmode Supply

90   Dimmer Polarity Reversal
91   78RPM Phono EQ
92   Guitar and Bass Sustain
93   Recording & Measuring Mic
94   Universal Preamp Mixer
95   Low Power -VE Supply
96   48V Phantom Supply
97   Hi-Fi Preamp
98   Auto Charger for Battery Hi-Fi
99   36dB/ Octave Infrasonic ('Subsonic') Filter

100   Headphone Adaptor for Amplifiers
101   200W MOSFET Power Amplifier
102   Simple Pre-Regulator
103   Subwoofer Phase Control
104   Preamp/ Crossover Mute Circuit
105   Build an Electrostatic Loudspeaker (ESL)
106   hFE Tester for Transistors
107   Phase / Polarity Reversal Switching
108   Switchmode PSU Protection
109   Headphone Amp

110   IR Remote Control
111   PIC Speaker Protection
112   Dummy Head Microphone
113   Hi-Fi Headphone Amp
114   Class-D (PWM) Power Amp
115   GainClone Amplifier (Part 1)
115   GainClone Amplifier (Part 2)
116   Class-D Subwoofer Amp
117   1.5kW Power Amplifier
118   Ultra Simple PC Peripheral Switch
119   Component Signature Analyser

120   Crowbar Speaker Protection
121   Reading Inductance
122   Ultra-Simple Mic Preamp
123   18dB/Octave Crossover
124   Dummy Load
125   4-Way 24dB/Octave Crossover
126   10A, 12V PWM dimmer/ speed controller
127   Two Channel TDA7293 power amplifier
128   Analogue VU Meter Bridge
129   Matrix Mixer

130   Inverse A-Weighting Filter
131   Light Activated Switch
132   Air Bearing Tonearm
133   PA-PC Audio Interfaces
134   4mA Current Loop Microphone
135   Phase Correlation Meter
136   Real-Time Audio Analyser
137   Bi-amped PA Amplifier
138   Mains Over/ Under Voltage Cutout
139   Mains Current Monitor
139A Simple Current Monitor

140   True RMS Adaptor
141   VCA Based Preamplifier (THAT2180)
142   Simple High Current Regulator
143   Tone Burst Generator/ Gate
144   Mains Power Sequencer
145   Silent Guitar Effects Switching
146   Overload/ Clipping Indicator
147   BJT Muting Switch
148   State Variable Crossover
149   Musical Instrument Graphic EQ

150   Wien Bridge based equaliser
151   High Voltage DC Supply
152   Bass Guitar Amplifier - Part 1
152   Bass Guitar Amplifier - Part 2
153   Frequency 'Isolator' EQ
154   PC Oscilloscope Interface
155   Variable High And Low Pass Filters
156   12V Trigger Switches
157   3-Wire trailing-edge light dimmer
158   Low-Noise Test Preamplifier
159   3-Wire Leading-Edge Dimmer

160   LM386, LM380 & LM384 Power Amplifiers
161   High Impedance Input Stages
162   Voltage Controlled Oscillator
163   Preamp Input Switching Using Relays
164   Signal Tracer
165   Valve Tester for Service Techs
166   Push-on, Push-off Mains Switch
167   MOSFET Follower & Circuit Protection
168   Low Ohms Meter
169   Battery Powered 'Audiophile' Amplifier

170   6dB/ Octave Active Crossover
171   Infrasound Translator
172   Wattmeter for AC Power Measurements
173   Constant Directivity Horn Equaliser
174   Ultra-Low Distortion Oscillator
175   Single Supply BTL Amp DC Protection
176   Fully Differential Amplifier
177   Constant Current Transistor Tester
178   Low Voltage Power Amplifier
179   Filament Lamp Stabilised Wien Bridge Oscillator

180   Amplifier 'Power Meter'
181   Audio Accelerometer
182   Maximum Length Sequence (MLS) Noise Generator
183   Signal Detecting Audio Ducking Unit
184   Li-Ion Battery Cutoff For Electronics Projects
185   Speaker, Microphone & Circuit Polarity Tester
186   Workbench Test Amplifier
187   Moving Coil Head Amplifier
188   Surround Sound Decoder (Mk II)
189   Audio Wattmeter (Measures True Power)

190   Microphone (including phantom powered) Muting Circuit
191   Peak Voltage & Current Detector For Loudspeakers
192   12V to ±12V Switchmode Supply
193   12V to P48 Phantom Power Supply
194   Withdrawn
195   Guitar 'Talk Box'
196   12V Float-Charge Battery Supply
197   Low Frequency Boost And High Pass Filter For Speaker EQ
198   MOSFET Relay
199   ABC New Years Eve Concert Equaliser

200   DIY LDR Optocoupler
201   Multi-Channel Trailing-Edge Dimmer
202   Piezo Preamplifiers
203   Guitar/ Studio Spring Reverb Unit
204   Frequency Shifter For Acoustic Feedback Reduction
205   4-Channel Mixer For Microphones Or Instruments
206   Guitar Vibrato/ Tremolo Unit
207   High Current AC Source
208   Amplifier Powered DC Protection Circuit
209   Resistor And Capacitor Decade Boxes

210   Electronic Fuse Circuits For DC and AC
211   Reverb Drive And Recovery Amplifier
212   High Impedance DC Voltmeter
213   DIY voltage controlled amplifier (VCA)
214   'Zero Capacitance' Guitar Lead
215   'P27-Revisited' 40W Guitar Amp
216   Speaker Emulator Dummy Load
217   Low Power 'Practice' Amplifier
218   High Q Gyrator Filter
219   Valve Guitar Amp Speaker Switch

220   Switchmode Buck Converter
221   Tweeter Amp Voltage Regulator
222   Transformerless Soft Start Power Switch
223   Dual Bench Power Supply
224   External In-Line Inrush Limiter
225   Inrush Current Test Unit
226   Versatile Tone Controls
227   Hybrid Relay For Speaker Protection
228   Negative Impedance Test Amplifier
228A Negative Z Test Amp Annex
229   Enhanced Reverb Mute System

230   Workbench Signal Routing Panel
231   Fast Discrete Opamp
232   Distortion Measurement System
233   Isolated Power DC-DC Supplies
234   Resistor Substitution Box
235   Current Feedback Opamp (DIY)
236   AC Millivoltmeter
237   JFET Test System
238   High Voltage, Low Current DC Source
239   Signal Detecting Power-On (Mk II)

240   10 Watt Audio Amp/ DC Supply
241   Z-Weighting Filter
242   Cosine Burst Generator (Mk II)
243   'Retro' Hi-Fi System
244   3-LED Level Indicator
245   TPSI3052-Q1 MOSFET Relay
246   Clipping Indicator
247   Tape Head Preamp
248   Low-Voltage Charge Pumps
249   Guitar Booster Circuits
250   Inductor Saturation Tester
251   Protected DC Load
252   6-Band Guitar EQ
253   18dB/Octave State Variable Xover
254   24/18dB Octave Asymmetrical Xover

ABX   ABX Comparator
X      A-B Switch Box

Project Suggestions

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