Also, use the search box at the bottom of the home page.
AGC Dynamic Microphone
Very Low Noise Amplifier
White and Pink (1/F) Noise Source
Noisemaking Circuits (police siren and doorbell chime)
Meter/Data Acquisition Amplifier
CD4069 LED Bar Graph - smooth transitions between 5 LEDs.
Measuring RF Voltages with a VOM
PicAXE Ionization Chamber
Altoids Tin LowFER Transmitter
Water Hammer Seismometer - use a tube of water to detect earthquakes
Live Data from the Lab
Games - the first game show timer was modified for better performance
Noisemaking Circuits (police siren and chime)
Temperature Controlled Ovens
Christmas Tree (or other plant) Moisture Monitor
Galloping Neons (array of blinking neon lamps)
Deer Repellent (seismic sensor)
Gag Circuits: magic lamp, dripper, remote control jammer
Ghost Detector - a changing electric field detector
CD4069 Atomic Frequency Standard (I know, a little overstated.)
Flip-Flop Flashers, Buzzers, Etc.
Flasher Ideas (LED flasher, silent metronome, low battery indicator, high voltage generator)
Tiny Crystal Oscillator High-stability gate oscillator uses two, 5-pin SOT packaged devices.
VHF Overtone Crystal Oscillator A circuit for VHF overtone crystals.
Low Distortion Crystal Oscillator
Ray's Wide Range VCO (Reprint courtesy of RF Design Magazine).
Circuit for LED Christmas Lights
Magic Lamp (Old idea, new twist.)
Line Powered Flashers (Great for Christmas lights, etc.)
Stepper Motor Experiment
Dome Lamp Dimmer
Emergency Backup Lamp
Battery Saver (Worth the effort!)
Windshield Wiper Delay
Dimmer/ Motor Speed Control
Split Supply for Op-Amps
Mercury Battery Replacement (also see Craig's versions)
Homemade "B" Battery
High Voltage Circuits
Power Supplies and Regulators (new low power discrete switcher)
Cockcroft-Walton Diode Voltage Multipliers
Battery Discharge Monitor
Finesse Regulator Noise
PicAXE Ionization Chamber
The X-ray Defender detects backscatter X-ray machines.
Radon Detector for the Student includes detailed instructions for a simple ionization chamber.
Radon Accessory for Radiation Detectors
Geiger Tube Simulator
World' Smallest Geiger Counter
Top of Ion Chambers page
My First Experimental Circuit
Large Cookie Tin Ion Chamber
Ion Chamber Bias Supply (Battery Topper)
Improved Transistor Circuit
Modify a CDV-715 for High Sensitivity
Neon Lamp as Resistor
Nuclear War Detector
Super-Sensitive Ionization Chamber
Components for Ion Chambers
Neon Bulb Quench Experiment
Crystal Radio and
Amplifiers and simple AM transistor radio circuits. (Also see diode detector info.)
The Amazing All-Band Receiver
Cellular Phone Helper
WWV Converter for the Car
Rush Converter for the Car
FM Band Preamplifier
Antennas Includes longwire, loading coil, active ferrite antenna, active short antenna, vertical.
FM Band Monaural Transmitter
Micropower AM band radio station and wireless "phono oscillator"
The Unfair Radio Transmitter
Superregenerative Air Band Radio
FM Radio Microphone with Internal Loop Antenna
The Bug Duster for cleaning out those pesky bugging devices.
detects digital RF
One Watt Class-C Amplifier
Two Diode Odd-Order Multiplier
Odd-order Diode Multiplier (Reprint courtesy of RF Design Magazine)
Diode Frequency Doublers
Unusual Frequency Dividers
HCMOS Gates Make Frequency Multipliers
Frequency Tripler Using the CA3028
Simple Divide-by-N Using '161s (ignore "74160" under the parts in the schematic - this is for the 74161.)
Waveform Conversion (sine to square and square to sine)
Ray's RF ID Transponder (Reprint courtesy of RF Design Magazine)
Inductor Quick Tester (battery topper)
Picoampere Leakage Tester
Transistor Spot Checker
V/I Curve Tracer
Synthetic Isolators - great for checking the SWR of antennas, amplifiers, mixers, etc.
Isolator/Circulator (Reprint courtesy of RF Design Magazine) uses ICs. Here's an external link to a reader's version: http://www.neazoi.com/circulator/index.htm
Curious C-Beeper (Also see the op-amp version down the page.)
Remarkable R-Beeper - by Tom Bruhns
VLF/LF Block Converter for the Shortwave Receiver
Altoids Tin LowFER Transmitter
VLF Whistler Reception
Oddball SID Receiver Experiment (60 kHz)
Schumann Resonance Detector (Area 50)
New Lightning Detector - especially built for the beginner
Sferics (spherics) Detector - a fancy lightning detector
Lightning Detectors (also see the readers' versions) and for testing a Lightning Simulator
Geiger counters! (weather?) or Ion Chambers
Cloud Charge Monitor
Another One-Transistor Cloud Charge Monitor
Note: the above charge monitors are really just toys. Although fun and interesting, their arbitrary zero limits them to monitoring changing fields and makes them inferior to a mechanical field mill.
Special thanks to RF Design for granting permission to reprint a few articles by Ray Page and myself.
Random Pages for the Search Engines to find: Repair Ideas
The information presented on the techlib.com web site is for reference or entertainment purposes only. No claims are made regarding the accuracy or reliability of the information. Circuit ideas and projects are intended for technically trained individuals who are qualified to evaluate their appropriateness and safety. Home-made devices are not reliable and unforeseen consequences may result from their use. Check all local, state, and federal laws regarding the use of home-made devices that transmit or connect to any utility. Do not construct and use illegal wiretaps or recording devices. Do not build bomb triggers or other illegal weapon components. Many circuits use or generate dangerous voltages even when powered by low voltage batteries. Many of the materials used to assemble electronic devices contain dangerous chemicals such as lead. Although the information provided is believed to be original or in the public domain, the devices and suggested uses may violate existing patents. Although practical jokes and gags can be entertaining, the involved parties may feel that they were damaged or that their civil rights were violated. Law enforcement organizations may consider electronic and electro-mechanical components to be paraphernalia for building illegal devices. Electromagnetic energy may cause disease.
That should cover it!
Remember, in our brave new world, consumer products are covered with warning stickers after hordes of lawyers and safety engineers review the design! Your home-made gizmo has no such protection and you are completely responsible for any damage it might cause or be alleged to have caused. Have a nice day ; )
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