Electronics

Electronic Circuits

Audio Circuits

	Audio Amplifier Circuits
	Directional Microphone [Area 50]
	AGC Dynamic Microphone [Area 50]
	Super-Sensitive PC Microphone [Area 50]
	Very Low Noise Amplifier (designed for a phase noise test set)
	Induction Receiver
	White and Pink (1/F) Noise Source
	VLF Whistler Reception See also ELF Monitor with AGC and Hum Removal and Baby's VLF Monitor [Area 50]
	Noisemaking Circuits (police siren and doorbell chime)

Communication Circuits

Telephone Circuits

Computer Circuits

	24 Line Parallel Interface for the PC (or just the schematic)
	Serial Port A/D - 12 bits, no power, cheap!

Misc.

	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
	Kitchen Circuits
	Galloping Neons (array of blinking neon lamps)
	Deer Repellent (seismic sensor)
	Shower Stopper
	Gag Circuits: magic lamp, dripper, remote control jammer
	Construction Ideas
	Sawdust Fuel - not exactly electronics [Area 50]

Oscillators

	Two-Transistor Atomic Frequency Standard
	Audio Oscillators
	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.
	Low Distortion Crystal Oscillator

Power Control

	Anti-Flicker Circuit for LED Christmas Lights [Area 50]
	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
	Lantern Flasher/Dimmer
	Dimmer/ Motor Speed Control

Power Supplies /Regulators

	Split Supply for Op-Amps
	Mercury Battery Replacement (also see Craig's versions)
	Homemade "B" Battery
	High Voltage Circuits
	Battery Chargers
	Power Supplies and Regulators (new low power discrete switcher)
	Cockcroft-Walton Diode Voltage Multipliers
	Battery Discharge Monitor
	Finesse Regulator Noise

Radiation Circuits

	Radon Detector for the Student includes detailed instructions for a simple ionization chamber.
	Radon Accessory for Radiation Detectors
	Geiger Tube Simulator (Area 50)
	World' Smallest Geiger Counter (Area 50)
	Top of Ion Chambers page
	My First Experimental Circuit
	Large Cookie Tin Ion Chamber
	Ion Chamber Bias Supply (Battery Topper)
	Experimenter's Chamber
	Improved Transistor Circuit
	Modify a CDV-715 for High Sensitivity
	Polonium Pen
	Neon Lamp as Resistor
	Nuclear War Detector
	Super-Sensitive Ionization Chamber
	Components for Ion Chambers
	Neon Bulb Quench Experiment
	Geiger Counters

"First Web Page of Radio"

	Crystal Radio and Amplifiers and simple AM transistor radio circuits.(Also see diode detector info.
	Regenerative Receivers
	Reflex Receivers
	The Amazing All-Band Receiver
	Cellular Phone Helper
	Aircraft Receiver
	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 (Area 50)
	FM Radio Microphone with Internal Loop Antenna (Area 50)

RF Circuits

	The F.E.D. detects digital RF signals
	One Watt Class-C Amplifier
	Two Diode Odd-Order Multiplier
	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)

Science

Test Equipment

	Large Inductor Quick Tester (battery topper)
	Picoampere Leakage Tester
	Transistor Spot Checker
	V/I Curve Tracer
	Measuring RF Voltages with a VOM
	Synthetic Isolators - great for checking the SWR of antennas, amplifiers, mixers, etc.
	Curious C-Beeper
	Remarkable R-Beeper - by Tom Bruhns

Video and Optical including security camera mods and photocell sensors

Weather Related Circuits

	Lightning Detectors (also see the readers' versions)
	Barometers
	Rain Detector
	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. Coming "soon" may be a no-moving-parts "field mill" using a smoke detector's ion chamber to sense the electric field. The bench test looks good and I hope to combine this new sensor with the JFET circuit to get DC precision and fast response.

Note: Many of these projects are appearing on other web sites and books without mention of the source. All of the projects on this website are original work unless I clearly say otherwise. That means I or the clearly identified author sat down with a blank tablet and started from scratch. These projects aren't rocket science but I don't want readers concluding that this site copies from other sources without attribution.

Safety Information and Disclaimer

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 ; )