Intermittent alarm
generator
Burglar alarm
Moisture
alarm
Fridge door alarm
Ultrasonic remote control & alarm
system
Door knob
alarm (PDF)
Water seepage
alarm (PDF)
Micro-power
over temperature alarm (PDF)
Personal silent alarm system
5 Zone
alarm circuit
Miniature loop alarm
Gate
alarm circuit
Perimeter monitor
Digital combination lock
Touch activated
alarm system
Active 2nd Order Filters
RC Notch Filter (Twin T)
3KHz
low-pass filter plus audio amp (PDF)
"A" Weighting Filter For
Audio Measurements
Multiple Feedback Bandpass
Filter
100W
Amplifier
18W Audio amplifier
25W MOSFET
amplifier
Headphone
amplifier
Portable headphone
amplifier
2W amplifier
8 watt audio amp
20W Amplifier
50W Amplifier
100W Audio amplifier
100W RMS Amplifier
2-Channel Power Amplifier
Push-Pull
Class A Amp using type 5687 dual triodes
Push-Pull
Class A 2A3 Stereo Amp
Single
Ended Class A2 SV811-10 Stereo Amp
Audio
amplifier output relay delay
HeadBanger Headphone Amp
2W
Amplifier
TDA2030
8 Watt amplifier
16 Watt amplifier
8 Watt amplifier
20 Watt Class-A Power
Amplifier
El-Cheapo - A Really Simple
Power Amplifier
Single Chip 50 Watt / 8 Ohm
Power Amplifier
Hi-Fi Headphone Amplifier
100W Guitar Amplifier
Death of Zen (DoZ) - A New
Class-A Power Amp
Soft-Start Circuit For Power
Amps
Thermo-Fan To Keep Your Amp
Cool
Audio Amp Output Power
Limiter
55W (Originally 75W) Power
Amplifier
300W Subwoofer Power
Amplifier
20 Watt / Channel Stereo
Power Amplifier
Phono preamp
Simple microphone preamplifier
Phono Preamp
Simple
microphone preamplifier
ECM
Mic preamp
Hi Fi
preamp
Electret mic
amplifier
Audio
preamplifier
Audio preamp
Low impedance
microphone amplifier
Analog
Tachometer for Gasoline Engines
Headlight On reminder with Light
Flashing High
Intensity LED 3rd Brake Light
Car clock
Car
message display
Car
interval wiper
Safety
indicator light
Speed limit alert
Portable CD Player
Adapter For Car
Car battery charger
Wireless Auto
Tachometer
Headlight reminder
Breath Alcohol Tester controlling a car ignition system
Parking sonar
Simple Car Preamplifier and
Artificial Earth
Interface
between GM's 5 Volt 8192 baud ALDL data stream and a PC serial port
3rd brake light
12V to 9V car
coverter
Car Nicad
charger
Economy radar detector
TempSentry
temperature sensor technical info and schematics
Datalogger based
on 68HC11
Analog input section based on AD9220
Light direction sensor
12-Bit ADC interface
Digital thermometer
Compost temperature and moisture monitor
Rain detector
Web-based
thermometer project
Honey Bee
counter (PDF)
Capacitance
type liquid level measurement (PDF)
Digital PC Oscilloscope
Serial
Port A/D-converter
Centronics
port D/A converters and low-pass filter
Water-level sensor
Big Mouth
GameBoy Camera
Parallel Port Interface
PSX
controler to PC MIDI converter
GameBoy Cart Programmer
Memory
game
Project: NES to
Atari 2600 controller interface
Pine Racecar Victory
Judge
PowerGlove Interface
GameBoy Schematic
GameBoy LCD schematic
GameBoy Power &
Cartridge schematic
GameBoy ROM+RAM+MBC1 Cart
Schematic
GameBoy MBC1 circuit
equivalent
Super GameBoy schematic
Quiz show indicator
Bingo!!! (on your tv)
Slot car TV cronograph
DIT shutterglasses controller
IR remote control system
for PC
IR
Receiver (Amplitude Modulated IR)
IR
Transmitter for Audio (Amplitude Modulated IR)
Universal IR-Remote
Lamp Controller
IR remote control
40KHz light
receiver (PDF)
40KHz TV-VCR
repeater (PDF)
Infrared remote transponder
Build an Infrared night scope
Decoding IR Remote Controls
IR
detector
PC IR Remote Control
An Ambient-Light-Ignoring Infrared Active Motion Detector
IR Ranging
Pyroelectric Infrared
Sensor
Simple IR
transmitter circuit
Simple
infra-red detector
IR
remote control extender
IR
remote control tester
Infrared repeater
40khz
IR Tester
555
timer 40khz IR Oscillator
IR detector / emitter
Implementing
Infrared Object Detection
Infrared gate
detector
Infrared relay
with relay output
Laser power supply
Laser
transmitter/receiver
20MHz VCSEL
3mW laser test circuit (PDF)
10MHz to
20MHz laser light detector (PDF)
Micro-power
40KHz burst laser diode driver (PDF)
40KHz laser
burst detector (PDF)
Modulated
laser diode tester (PDF)
Experimental laser data link
Winking LEDs
LED flashing light
LED initials
1.5 Volt LED Flashers
AC Line Powered LEDs
Astable Multivibrator
9 Second Digital Readout Timer
9 Second LED Relay Timer
16
Stage Bi-Directional LED Sequencer, other sequencer and flaser circuits
10 Stage LED Sequencer
28 LED Clock Timer
Fading Red Eyes
Two Transistor LED Flasher
16 Stage Bi-Directional LED Sequencer
Expandable 16 Stage LED Sequencer
LED Photo Sensor Circuit
LED chaser
7 Segment LED
Counter
1.5V LED
flasher B (PDF)
Low current
LED flasher (PDF)
1.5V LED
flasher A (PDF)
Flashing
LED advertising badge (PDF)
Pulsed LED
test circuit (PDF)
Low battery
voltage flasher (PDF)
Adjustable flashing LED
LED Mood
Light
LED Audio VU Meter
LM3909 LED
flasher
Picxie 2 - 8x8 Animated LED
Signboard
Disco
style Strobe Light
Varying Brightness AC Lamp
12 Volt Lamp Dimmer
120VAC Lamp Chaser Using Solid State Relays
Flashing Neons (NE-51 / NE-2)
Sequencing Neons (NE-51 / NE-2)
Touch Activated Lamp
220V Flashing
lights
Coutesy lamp
Bedside lamp timer
TRIAC light dimmer
12VDC Fluorescent
Lamp Driver
Strobe light
Adjustable Strobe
Light
5W
Fluorescent light intensity modulator (PDF)
1W
Fluorescent lamp night light (PDF)
Electronic night light
LED
Mood Light
LX-800 Lighting system
Xenon Strobe Light
Lamp
flasher/dimmer
PWM light bulb
regulator
Radiation
Dosage-Rate Meter
Heartbeat
monitor
Cranial
Electrotherapy Stimulator
Automated crib
lights
Joigging timer
Tan timer
Muscular
Bio-stimulator
Pedometer
Simple lie detector
The ESP SIM (Sound
Impairment Monitor)
Z80 core #1- Z80
CPU and memory (PDF)
Z80 core #2- Z80
CTC and SIO
Z80 core #3-
RS-232 drivers for the SIO
RS485-Version of
the SAB80C535-Microcontrollerboard
PC IR receiver based on PIC16F84
AT89C2051/4051scanning 7-segment display and keypad
AT89C2051/4051 Driving dot LED
AT89C2051/4051stepper motor interface
AT89C2051/4051connecting dumb terminal
Simple
RS232C Level Converter using Transistors
C-52
EVB Robot Controller
Mains clock
controller using AT89C2051
AT89C2051/4051 Easy-Downloader
AT89C51/52/55 Easy-Downloader
PIC16F84
programmer
PIC16F84
miniature real-time controller
Isolated RS232 for PIC16F84
PIC16F84 debugging terminal
MiniLOGGER
V1.0
Atmel
89C Series Flash Microcontroller Programmer
AT89C2051
real-time controller
PIC12C508
Night-light saver
AT89C2051
Night light saver
Atmel 8051
Flash Based-Microcontroller Programmer
AT89C2051 Digital thermometer and clock
12C508 Smart Lock
Build a PIC
controlled DDS VFO, 0 to 6 MHz
PIC
controlled DDS VFO, 0 to 6 MHz
TCP/IP stack and WWW server in a PIC16F84
PIC16F84 line following robot
50 MHz
frequency counter, voltage meter & SWR/PWR indicator
Embedded controller based
on MC68HC11F1
RDS Encoder - digital
part
Freign
vocabulary recollector
Embedded
system to send e-mails (small TCP/IP stack)
Speaking
clock using PIC & ISD device
Speaking
doorbell using PIC & ISD device
Whistle
detector using 8-pin PIC
PIXpand
PIC16F84 mechanically scanned clock
68HC11 stepper
motor control
Serial to parallel converter
using the AT89C2051
AT89C2051 serial COMs to LED
driver
101 AT Keyboard
to ASCII Decoder using 68HC705J1A MCU
DTMF tone
decoder using Basic Stamp
A Scenix (and PIC)
Programmer
Long-period
watchdog timer
PIC16F84 Range Finder Project
Generate video
signals in real-time using a PIC16F84
PIC Project #1 - RS232 to I2C
Interface
Dual PIC16C84 prototype
board
Talking
YODA project (PIC16C84)
PIC16F84/PIC16F87x-In-System-Programmer
Microcontroller interface for 5KW microwave oven
PIC16F84
Based Morse Code Reader
Interfacing piezo elements to a
microcontroller
PICADC - a free,
PIC based "intelligent" A/D converter
AT89C2051
line-follower robot
PIC16F84 sound controlled
Christmas lights
Convenient PIC module
Spread spectrum transceiver controlled by PIC
68HC11 based RDS decoder
PIC16C84 VT-52 Emulator for Linux
Temperature
controlled based on AT89CX051
2-wire LCD interface using
PIC16CF84
PIC16F84 Serial I/O-expander
with PicBasic
PIC R/C Servo
Controller
Microprocessor
RS-232 Reset
A PIC-Based Keyboard Emulator
ScanMate audio
activated recorded
Remote control
encoder/decoder with PIC16C620 & PIC12C508
Electronic door
codelock with PIC16F84
Automatic door opener
with PIC12C508
Infra/radio
remote control transmitter/receiver with PIC
http://www.vekoll.vein.hu/~jap/electronic/codelock.html
Automatic door
opener (PIC)
Picxie 2 - 8x8
Animated LED Signboard (PIC16F84) Picxie 2 - 8x8 Animated LED Signboard
PIC-FC1 Frequency Counter
10
tricks for interfacing to the PIC16C508
Interfacing the
PIC16C508
PIC 5x7 display
Analog to digital
conversion notes
Multi-chip programmer
A Schottky-based Saw-to-Tri converter
Saw to triangle converter
Improved saw to triangle converter
Voltage controllable LFO
White noise generator
Horror movies sound
effects
Sound amplifier
Temperature
sensitive oscillator
Old-fashioned siren effect
Simple VOX circuit
Low Power Op-Amp - Audio Amp (Intercom)
555 Tone Generator (8 Ohm Speaker)
3 Transistor Audio Amp (50 milliwatt)
Low Frequency Sinewave Generator
Audio level
indicator
Room noise
detector
Amplifier timer
Bell ring
generator
Amplified ear
Precision audio
millivoltmeter
A Stereo Digital Volume Control based on the CS3310
Voice record/playback using ISD 1000A
Audio Graphic Equaliser
Analog VU meter
Voltage controlled amplifier
Audio graphic equaliser
Intercom preamp
FET audio mixer
Microphone mixer
Tone control
Digital volume
control
Sound level meter
CMOS IC audio
oscillator
Very loud
beeper (PDF)
Digital
noise generator (PDF)
Condenser microphone hookup
Phase shifter
Paradoxical Sound Syntheizer
Audio line isolator
Dynamic microphone to electret microphone input
Line
level signal to microphone input adapter
Simple
two line output combiner
Electret microphone powering circuits
Use
amplifier phono input as line level input
Speaker signals to line level inputs
Spring reverb unit
Sine wave
generator
3-Band
equalizer
6-Input mixer
Doorphone intercom
Stereo line driver
Audio
notch filer
Peak
reading audio level meter
Tone
control
Electronic canary
Improved PL
tone decoder
Magnetic
cartridge amplifier
LM358 preamp
Sound
detector
Tone detector
Tone generator
Warbler
Voltage
Controlled Panner
Low Noise Microphone
Preamplifier
Bridging Adapter For Power
Amplifiers
Simple Surround Sound
Decoder
Simplest Ever Amplifier
Bridging
Stereo Width Controllers
Power Amplifier Clipping
Indicator
Phono Preamps For All
Digital Delay Unit For
Surround Sound
Parametric And Sub-Woofer
Equaliser
High Quality Sound Mixer
Loudspeaker Protection and
Muting
Direct Injection Box for
Recording & PA Systems
Minimalist Discrete Hi-Fi
Preamp
Signal Detecting Auto
Power-On Unit
Load Sensing Automatic
Switch
Amplifier thermal protection
Active Sub-Woofer and
Controller
Balanced Line Driver &
Receiver
VU And PPM Audio Metering
Variable Amplifier Impedance
Linkwitz Cosine Burst
Generator
Low Noise Balanced
Microphone Preamp
Fast Audio Peak Limiter
Subwoofer Equaliser
Audio output
level meter
Chaos generator
Simple BFO metal detector
Electromagnetic Levitator
Build Your Own Digital
Setting Circles For Your Astronomical Telescope
Electric field disturbance monitor
Discrete Set/Reset Flip Flop
Monostable Flip Flops (one shot)
Discrete Bistable Flip Flop
Plant watering
watcher
Capacitance sensor
Whistle responder
Nocturnal animals
whisker
12V DC
electronic door chime
Random noise
generator
Hardware random bit
generator
Analog pulse counter
Analog opto-isolator
Pulse width modulators (PWM)
Pulse width to voltage converter
Fantastic Atom Expander
Black Light
Computerize Your
Room/Home
Flash slave trigger
A Visual CW
Zero Beating Aid
A two-way Morse
practice set
Tesla power receiver
Basic op-amp
circuits
Supervisory Control
And Data Aquisition project (for Home Automation and Security)
Ion detector
1uS light
pulse descriminator plus F to V converter (PDF)
Broadband
2MHz optical fiber receiver (PDF)
Modulated
light received (PDF)
1uS light
pulse receiver plus post amp (MISC)
Broadband
5MHz optical fiber receiver (PDF)
High-speed
light receiver (PDF)
Basement
doorbell beeper (PDF)
Time to dust
indicator (PDF)
Low-power
optical interrupter (PDF)
Simple
nitrogen spark generator (PDF)
Ultrasonic transducer oscillator circuit
Build logic gates using discrete parts
Jacob's Ladder
Variety of quick designs
Fogger smoke machine
Electric field
disturbance monitor
Dual comparator forms
temperature-compensated proximity detector
Electromagnetic field detector
Ultrasonic dog whistle
An Inexpensive X-ray Machine
Magnetic
levitation circuit
Ultrasonic switch
Very
basic circuits
Bat detector
FCTS Project
Morse Code
Beacon Keyer
Lightning
Activated Camera Shutter Trigger
Electronic Dazer
Morse Code Practice
Keyer 1
Morse Code Practice
Keyer 2
741 Light Sensor
Fluid level
detector
Full-duplex
doorphone
Scaling ADXL50 accelerometer output
R/C Receiver <->
Joystick Port Interface for Flight Simulators
LED traffic lights
Two-tone siren
HEXBOT robot
Alf: The
Robotic Matchbox car
A Low Cost Thermal Peak
Detection Charger
A Miniature High-Rate Speed
Control with Brake
An On/Off Motor Control with
Brake
0-10V
control for RC servos
Simple flashing light circuit
Simple flashing light circuit
A dual alternating flashing
light circuit
Simple flashing light circuit
A dual tandem flashing light
circuit powered by a 9 volt battery
Simulate the Gyralite (dual
flashing headlights).
Simple train detector using
ambient light and a photocell
Simple charge rate monitor
Deluxe charge rate monitor
"CLONEPAC" memory module
for Futaba 8UAF/8UAP
Battery pack discharger
Plane locator
Plane locator 2
Battery low voltage alarm
Battery low voltage alarm 2
Ultimate battery low
voltage alarm
Building an RF Remote Control
System
Two tone train
horn
Radio Control
Battery Backup
Glow Plug driver
for model engines
Electronic Thermostat Relay Circuit
Interfacing 5 volt CMOS to 12 volt loads
Light Activated Relay
CMOS Toggle Flip Flop With Relay(CD4013)
555 Timer Monostable Circuit Using Pushbutton
Current loop interface
Switching solenoid driver
Modular relay system
Light/dark detector
Pulse Width
Modulation DC Motor Control
Stepper motor
controller
Touch switch
12V Sump Pump
Control
Pushbutton
one-shot and latch (PDF)
Charge
coupled bi-directional power MOSFET relay (PDF)
Finger
touch activated switch (PDF)
Machine
vibration triggers hour meter (PDF)
Solid state
relay (PDF)
Line-powered
Xenon flash transmitter (PDF)
9V Xenon
photoflash controller (PDF)
AC switching with TRIAC from TTL
Control 120VAC relay with TTL
Driving a relay with a CPU
Power-line Appliance Controller
Combination-controlled, fully customizable RF remote control
Thermoelectic controller (scriptable thermometer)
Stepper motor
positioner
SN754410
Dual Motor Driver Board
Temperature monitor
Cold activated switch
Voltage comparator switch
Dark activated switch
DC Push Button Motor Control Circuit
Light detector
Sound operated switch
Touch Switches
Detect fan failure with a single transistor
http://www.rentron.com/SerialServo.htm
Constant
Temperature Circuit
PWM DC Motor Speed
Control
Solenoid
starter
CO2
controller for planted tanks
Light activated
relay
Drum machine
Simple MIDI-to-CV converter
Sounds effects unit
ETI 603 Sequencer
Synthesizer schematics
Peak-reading meters
Octave screamer
Optical Theremin - electronic musical instrument
Spring reverb unit
Metronome and pitch
generator
Mini metronome
Simple colour organ
Guitar fuzz effect
8 note tune player
Colour (Sound) Organ
Transisor organ
Audible metronome
Visual metronome
Simple
line mixer
Simple
MIDI tester
Electronic metronome
Guitar Reverb
Pedal
Guitar Tremolo Unit
Spring Reverb Unit For
Guitar
Ultra Simple Bass Guitar
Compressor
Vox AC30 Guitar Amplifier
Simulator
Guitar Vibrato Unit
Musical Instrument
(Expandable) Graphic Equaliser
D.C. Mixer for music
synthesizers
I2C printer
port adaptor
RS232C
Level Converter
Isolated Full Duplex RS232C Interface
ISA 8-bit output
card
PC based 7-segment
rolling display
Parallel
print capture system
Modem Rockwell RCV336/ACF
model V1433VQR ext.
Genius Mouse schematics
PC
serial port receiver
Parallel port relay interface
ISA 48
I/O digital card
Parallel (Printer)
Port Interface
RS-232 line monitor
and loopback cables
A Serial
Infrared Remote Controller
Interfacing 16x2
character :LCD to parallel port
8254 Timer and
Counter Board
Serial to
ECP interface
A PC-Based
LowFER Frequency Synthesizer
General purpose 48-bit ISA
parallel I/O card
4-channel 8-bit analog-to-digital converter for PC
Printer port ADC
Parallel
port ADC based on MAX147
Analog Signal Acquisition for PC Printer Port
More accurate PC/AT clock
Getting power from RS-232 interface
Barcode scanner
PC
thermometer
Parallel
port servo controller
Connect two CD-ROM drives to one soundcard
Headphone driving circuit for soundcards
Get
power out of PC parallel port
Null
Printer Adapter
PC
speaker volume control circuit
How
to get power from PC to your circuits
RS-232 surge protection
Simple
RS-232 serial port buffer circuit
Get power
out of PC RS-232 port
Sound
Blaster Microphone Preamplifier
Sega 3D
glass interfacing circuits
Convert Atari-style joystick to PC joystick port
Fake Joystick circuit
Using the joystick port as general purpose input
Connect other circuits to PC joystick port
Schematic of a standard PC joystick
Simple PC SmartCard reader
Fax to modem interface
DC-DC Power Supply from
car 12V battery to PC motherboard
Linux Infra-red Remote Control (LIRC)
Compter microphone
Laptop
Computer Serial Port Power Booster
HamComm Interface
Hi-Fi PC Speaker System
IDE hard-disk
interface for Amiga 500
Parallel port ADC/DAC
Parallel port ADC using
ADC0804
High speed 20MSPS ADC
interface
9-pin null modem
cable
24-bit parallel
port interface with 8255 for Commodore computer
24-line PC digital
interface (PDF)
SPDIF-interface to AudioPCI
SHARP
palm-top/hand-held to RS232 serial converter
Casio organiser hardware
Casio datalogger
Power
supply provides +5VDC regulated, +10VDC unregulated and 7.5VAC
Basic increase in
DC voltage
Power
Tool Torque Control
Generating Negative 5 Volts from 9 Volt Battery
LED Battery Condition Indicator
LM317 Variable Voltage Regulator
LM317 Regulator With Pass Transistor
High Current Regulated Power Supply
Simple Variable Voltage Source
Variable 3 - 24 Volt / 3 Amp Power Supply
2 watt switching power supply
Variable Voltage and Current Power Supply
Low Power DC to DC Converter
Constant Current Battery Charger
Variable DC power
supply
Using the 78xx Series Voltage Regulators
6V to 12V Converter
Tesla coil / HV
generator
12VDC To 120VAC
Inverter
High Current Power
Supply
Dual Polarity Power
Supply
High Voltage High
Current Power Supply
Transformerless
Power Supply
Fixed Voltage Power
Supply
Voltage Inverter
Voltage Inverter
1A Variable Regulated
Power Supply
Negative
voltage generator
12V battery
capacity tester
NE555 Low Voltage
Battery Disconnect Circuit
Power
reminder beeper (PDF)
Unplugged
power cord alarm
Machine
power loss beepter (PDF)
HV supply: 12VDC in, 12KV out
Generating -5VDC from +5VDC
Filtering PC bus POWER
Bidirectionall power inverter
Adjustable
power supply using LM317
Simple +5V
power supply circuit
12V
30A power supply
Dual
regulated power supply
Fuse
blown indicator
Gyrator circuit
Variable power supply
Nicad
battery charger
Regulated 12V supply
Unregulated power supply
12 volt battery
monitor
12 volt power
supply
5 volt power
supply
Battery
voltage monitor
LM3914
battery monitor
Multiple
voltage power supply
Voltage doubler
Voltage inverter
PWM Motor
Speed Controller / DC Light Dimmer
PWM
Motor/Light Controller
Low Power LED
Voltmeter
PWM
Motor/Light Controller
PWM
Motor/Light Controller variants
Low Power
LED Voltmeter
Temperature
Controlled NICD Charger
Simple Capacitance
Multiplier Power Supply For Class-A Amplifiers
Simple DC Adapter Power
Supply
Variable Dual Lab Power
Supply
Charger for gel lead
acid batteries
12V to 120VAC
inverter
Nicad Battery
Discharger/Capacity Indicator
CW
RECEIVER 40/80 meter CW receiver
TRF AM Receiver circuit
Receiver building
blocks
Crystal radio
Automatic message sender for CB
RF Sensing relay driver
Vibrating pocket bug detector
2MHz RF
Oscillator
50-150MHz Overtone Oscillator
Simple Op-Amp Radio
NASA TURFTS - TDRSS
User RF Test Set
HF
Linear RF power amplifier
100W
HF Linear AMP
3W FM Transmitter
Crystal radio
Op-Amp Radio
Car radio tunes
the Amateur Bands
Crystal set that
requires no antenna
80m Direct
Conversion Receiver
A compact L-match ATU
for portable use
Morse Adaptor for
your VHF/UHF FM rig
An end-fed
antenna, L-match coupler and resistive bridge for HF
AM Broadcast Band
Regenerative Receiver
50 MHz to 146
MHz Converter
Hear Amateurs on
your Shortwave Radio!
Compact 20 14 MHz
direct conversion receiver
Hear Amateurs on
your FM Radio!
RF actuated CW
monitor
LF to HF
Converter
Super 80 ultra-simple
SSB receiver for 3.5 MHz
The MRX-40 Mini
Receiver
Phase Shift Radio
Direction Finder
Bug detector
175KHz
inductive pulse receiver (PDF)
200-400 MHz
voltage controlled oscillator
Icom CT-17 Logging &
Control Interface Level Converter
AM/FM/SW active antenna
RF Sniffer <.5 to >500 MHz
Frequency
Synthesizer
Four Channel Wireless
Transmitter and Receiver
Wireless event receiver
Talking receiver
Wireless motion
detector
418MHz Control RX/TX
2N2222 40 Meter CW/DSB
Transceiver
AM
receiver
Field
strength meter
MW
preamplifier
Simple
field strength meter
4 band
double-tuned preselector
ZN414 AM
receiver
ZN414
shortwave receiver
Phased lock loop
schematic
SOP direct
conversion receiver
Simple UHF dummy load
Receiver
30m direct conversion
receiver
Popcorn direct conversion
receiver
40m direct conversion receiver
80m direct conversion
receiver
R-399-A Communications
Receiver
136 kHz direct conversion
receiver
How to Build a 300MHz AM, RF
Remote Control System
RF
Modem Robotics Project
Smooth Tone
Clickless CW Sidetone Generator
Variety of
receiver converter projects
One
transistor FM receiver
42
Mc Band to 88 Mc Band (retrofit converter) Project
50MHz Assistant (Preamp & Power
Amp.)
Bug detector
Basic RF
oscillator
Superregenerative
27MHz receiver
Radio Control
Electric Switch
56K RF Modem
80M ARDF
direction finder
AA
battery solar charger
Solar
Panel Charge Controller / Low Voltage Disconnect Circuit
Solar
Panel Current Meter
Solar
Charged LED Flashlight
AA
battery solar charger
Solar
Panel Charge Controller / Low Voltage Disconnect Circuit
Solar
Panel Current Meter
Solar cell
Nicad charger
Phone in use circuit
Digisound ring modulator
Incoming
call indicator
Telephone Ring Generator Using 60Hz Power Transformer
Telephone Ring Generator Using Switching Power Supply
Telephone In-Use LED Indicator
Telephone In-Use Relay Circuit
Telephone Audio Interface
Ringing Phone Light
Flasher
Phone Busy
Indicator
FM Telephone Bug
Cut Phone Line
Detector
Simple Phone Tap
Telephone Hold
Button
Telephone Recorder
1-line
telephone status indicator (PDF)
Line in use
indicator (PDF)
4-line
telephone status indicator (PDF)
Caller ID decoder
Telephone in use light
Detecting a telephone RING
Phone In-Use Light
Phone to audio interface
Phone Off-Hook Indicator
'phone rang' indicator light
Phone Line to Audio
Phone in-use
Telephone Line Monitor
Use old phones as an intercom
Phone-In-Use indicator
Hold function for Telephone
Digital/Standard Phone Line Tester
Universal telephone hold
Talking phone dial
monitor
Telephone line simulator
Telephone privacy adapter
Telephone ringing circuits
Simple circuit to connect telephone equipment to audio mixer
Cut phone line
detector
Tri-Waveform
Generator
JFET crystal testing oscillator
ESR Meter
Line Output /
Flyback transformer tester
AC Line Current Detector
Triangle and Squarewave Generator
Voltage probe
Live line detector
Electric field & leakage
detector
Simple polarity
detector
RCM710 Electronic Scale
3 - 12 MHz Signal
Generator
Some simple test
equipment to build
RF Power Meter for
the QRPer
Dip Oscillator
for HF
Two Tone Audio
Oscillator (use for SSB tests)
Simple
pH meter
Temperature compensated pH meter
pH meter
with calibration
LASER/LED
light output intensity meter (PDF)
Frequency and capacitance meter
Simple light sensor adapter for oscilloscope
Time Domain
Reflectometer (TDR)
EMF field probe
Function generator
Logic probe
Zener diode tester
Signal tracer &
injector
Pulse Reading
Logic Probe
Pink Noise Generator for
Audio Testing
Audio Millivoltmeter
Audio Test Oscillator
Full Featured Transistor
Tester
Opamp Design and Test Board
Microphone Circuit Test
Oscillator
Distortion Analyser
Self Oscillating Amplifier
for Distortion Testing
Build a
Magnetic Field Immunity Tester
555 Timer IC
Tester
555 go / no-go
tester
12V Lead-Acid
Battery Monitor
Continuity tester
2
Continuity tester
Logic probe
220V wiring
detector
In-circuit electrolytic tester
PIC logic probe with pulser
Staircase
wave generator
1 Second Time Base From Crystal Osc.
Power-On Time Delay Relay Circuit
Low Voltage , High Current Time Delay Circuit
Power-Off Time Delay Relay Circuit
Generating a Delayed Pulse With a dual 555 Timer
1KHz Sinewave
generator
Timed beeper
Weign Bridge generator
Time Delay Relay
Time Delay Relay
Wide-swing Variable
Crystal Oscillator
Circuit that
momentarily closes a pair of contacts at long intervals
Line powered
60Hz clock generator (PDF)
Micro-power
pulse generator (PDF)
Darkroom
camera shutter timer
Divide by
1.5 counter (PFD)
High-output
square wave generator (PDF)
D Flip-flot
one-shot circuits (PDF)
Clock divider
Clock doubler
CMOS oscillator
Crystal 32.768KHz CMOS Oscillator
Crystal oscillator
Cheap 40KHz clock
Stable 40KHz clock
'Rounding Off' a square wave
Switch debounce using 555
Square wave to sine wave converter
Micropower
pulse generator (PDF)
Push Button Switch Debouncer
Square wave oscillator
Clock generator
555 Timer Tutorial
+ Circuits
Portable 40W CW
transmitter
Spark-gap transmitter
Wireless microphone
A 3m (100 MHz)
small bug
Basic FM
Transmitter
Micro Power AM Broadcast Transmitter
FM Beacon Transmitter (88-108 MHz)
FM transmitter
Two Valve 40m CW
Transmitter
Frequency agile 80m
CW QRP transmitter
80 metre DSB
transmitter
One Valve CW
transmitter
175KHz
inductive pulse transmitter (PDF)
Small Radio Transmitter
FM Telephone Transmitter
Micropower Event
Transmitter
FM
transmitter
4
transistor transmitter
FM
transmitter
Op-amp
based FM transmitter
Miniature FM
transmitter
Sensitive FM
transmitter
Simple RF
transmitter
1.5 volt
tracking transmitter
Tracking
transmitter
Micro Power FM
Broadcasting Circuits
Low Power FM Transmitter
30-Meter QRP
Transmitter for Morse Code
Miniature FM
Transmitter #1
Miniature FM
Transmitter #2
Miniature FM
Transmitter #3
Light sensing RF
transmitter
Micro-Spy with FETs
Micro-Spy with USW
Micro-Spy with TTL
Audio / video
distribution amplifier
Driver for multiple VGA
monitors
Closed-Caption
Decoder
PIC-Tock video
clock
Video signal amplifier
MC1374 based TV
transmitter
TV transmitter
Simple TV transmitter
Video
signal edge enhancement
Video amplifier
Digital volt meter with video output
Video switcher (PDF)
Video switcher
TV/Radio antenna cable galvanic isolator
S-video to composite video adapter
VGA
converter for video projectors and fixed frequency monitors
VGA
to TV converter
VGA to PAL and NTSC converter
Do-it-Yourself VGA ro PPrPb Cable
Many video amplifier circuits
includiing transmission over UTP (PDF)
Mark II video digitiser
Video digitiser
Audio-video
switch
