Free Electronic Transmitter Circuits, Radio Circuits Audio Amplifier and Spy Surveillance Circuits

Radio Circuits -Transmitter Circuits
Audio Amplifier Circuits - Hi Gain Amplifier Circuits
Spy and Surveillance Circuits - Video Circuits

high gain audio amplifier circuit
Electronic Spy Books From John Wilson
How To Sell Your DIY Electronic Products
Stealth Electronics and Spy Circuits
High Gain Audio Listening Spy Circuit
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John Wilson, Electronic Surveillance Circuits
Most of The Radio Circuits, FM Transmitter Circuits, Hi Gain Audio Amplifier Circuits, Video and Spy Circuits you will find on this site are unique and can not be found anywhere else on the net. Electronic circuits that have been designed, engineered and for years manufactured by John S. Wilson Jr. All are Free. A few others have been added. We hope you enjoy the exciting and new electronic circuits below and will visit us often.

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RF Transmitter Circuit - BBG
1/2 Watt VHF Crystal Locked
Voice Transmitter - FM. Full Production Layouts
  Hi-Gain Speaker Listening Amplifier
A very powerful eavesdropping amplifier
Using a regular audio speaker
Wall-Door-Window Amplifier Circuit
Eavesdrop thru Walls, Windows and Doors
A Fantastic Spy Amplifier - A15 Amplifier Circuit
  Distance Audio Amplifier Listening Circuit
A very powerful eavesdropping amplifier originally
used to locate illegal activities. Full Layouts.
Crystal Controlled Voice Transmitter
Sub-Miniture RF FM Voice Transmitter circuit
  Repeater / Recorder Circuit
Originally used to record Drug Dealer Conversations
Infrared Detector Circuit - IR12
Can be use to receive, test a and measure
the results of anything in the Infrared spectrum. Includes a Circuit Board Layout by Pete Zenner
  Dual Powered, Voice Transmitter
The DPT ( Dual Power Radio Frequency FM
Transmitter Circuit is a dual powered Voice
Transmitter VHF Crystal Controlled.
Telephone Bug Listening Circuit TE-23
The circuit is clipped across the pair, home,
panel box or even on the main cable leading
from the pole to the home
  Pen FM Transmitter Crystal Controlled
Pen FM Transmitter Circuit - Xtal Locked, 150 Mhz
This Micro transmitter is built into a fountian pen.
The ultimate Spy device.
Tracking Transmitter Circuit - VHF
Uses a 555 timer circuit to generate a
1 second on and .2 second off pulse. Crystal
Controlled and locked for absolute stability
FMNB Modulation.
  "Micro" 3V Crystal Voice Transmitter
The AB1 Transmitter  became popular among drug
squads.The circuit is extremely small and transmits a
frequency of 150 MHz. All layouts, Board, Breadboard and Stripboard.
Silent Carrier To Beep Converter
Circuit turns a silent carrier into a beep
at the receiver. It only requires a patch cord
from the scanner ear port to this device.
  Pete Zenners Acoustic Stetho - #200
All Layouts Included. A high gain amplifier which is specifically designed to convert physical vibrations into sound. A Law Enforcement Amplifier Circuit.
Concealed Briefcase Interface Circuit
A portable unit to set up in the front seat of a
car or in a van to monitor "A Wire" or in non
law enforcement terms, a transmitter being
worn by someone on their body.
  Phone Transmitter - Xtal Locked 1.5 V FM
Signal will transmit both sides of the conversation for
miles. Sends out a continual blank carrier when the
target phone is on the hook and transmits both sides
of the conversation - Off Hook
3V Button Cell - 3 MW Voice Transmitter
The unit was used with an RF Repeater concealed
in the trunk of an automobile nearby. built using a
surface mount board, the size of a postage stamp.
  Window Bug Transmitter - FM VHF
Originally used on the outside of a mobile home on a
back window out in the woods that would transmit all
of the voices on the inside of this trailer - WB1
Screw In "Button" Telephone Xmittr
An FM Transmitter built into an old T-1 element.
I dumped the carbon out of it, and modified it with a
Heil micro HC-4 Microphone element. Creative thought on how to apply to modern day phones.
  My Past Electronic Labs
A Lot Of Folks have asked me over the years if I have
any old photos of some of the facilities where
thousands of Wilson Products were engineered
Yep, and here are some old photos
5VT - Crystal Controlled FM Transmitter
The 5VT Transmitter uses a small 1.5 V "N" battery
or can use a hearing aid battery if you surface mount
the device rather than use a "Thru-The-Hole" board.
  Electronic Surveillance Related Books
Here you will find books written by John S. Wilson Jr.
A Master Engineer of Electronic Surveillance Products
for over 50 Years. "A Wealth Of Knowledge."
3V VFO FM Transmitter - Adjustable
A Single Stage, Postage Stamp Size, adjustable FM
Voice Transmitter. Complete with all layouts, Board ,
Breadboard and Stripboard.
  RF Coil Calculator - For Transmitters
RF coil calculator that allows you to compute the inductor, capacitor or frequency in the tuning (Tank Circuit) of any rf transmitter or amplifier circuit.
7 Watt Audio Amplifier Circuit
Audio amplifer circuit uses a LM383 IC amp and will provide up to 7 watts of output power for those who want to really experience their audio.
  741 - LM386 Light Wave Receiver Circuit.
This light wave receiver consists of a 741 operated as a preamplifier and an LM386 operated as a power amplifier. Receives Lasers, Infrared, etc.
TL071 Microphone Preamplifier Circuit
A high quality, low noise microphone preamplifier circuit. This circuit uses a TL071 IC Chip. A nice preamp for building a Super Spy Amplifier circuit.
  Speaker To Recorder Patch Cord
If you have ever wanted to connect the speaker on your receiver to a recorder, this circuit shows you how to do it. Also to dub from one recorder to another.
Easy Build FM Voice Transmitter Circuit
An Easy To Build FM (Voice) transmitter circuit that operates in the 88 to 108 FM band, or into the VHF bands. Very Simple Low Parts.
  Field Strength Meter Circuit - All Bands
The famous #016 Bug-Sniffer field strength meter circuit that was printed in Mick Tyners Book "Spook Book 1 It is extremely sensitive.
Telephone Transmit Circuit - Adjustable
A very small telephone VHF Adjustable Voice Transmitter circuit that clips to the telephone wires. VFO and transmits both sides of the conversation.
  Telephone Button Transmitter Circuit
The original telephone button transmitter circuit of John S. Wilson Jr., photos shown in the link - Screw In "Button" Telephone Xmittr in this menu.
Electronic Touch Switch Circuit
An electronic touch switch circuit has many applications and can be modified for a lot of other applications.
  Video Transmitter, Sender Circuit # 1
This a simple video sender transmitter circuit, easy and simple to build, operates in the VHF TV channels and will accept baseband video signals.
Video Transmitter Sender Circuit # 2
A simple Video Transmitter Sender Circuit is designed to operate / transmit video to a portable battery operated TV on channel 2, 3 or 4.
  Video Transmitter Sender Circuit # 3
A very powerful video transmitter, sender circuit that transmits it's signal for quite a distance. It has a power output of 1/2 Watt. Excellent Video Transmitter.
Infrared Voice Transmitter Circuit
Infrared voice transmitter circuit. used in situations where an RF transmitter can not be deployed.
  Telephone Activated Power Supply Circuit
Telephone activated power supply circuit, a very unique design. The clips clip on to the telephone pair, red and green wires, anywhere along the pair.
Video Transmitter Circuit Xtal - UHF
Video Transmitter circuit that uses a 55 MHz 3rd Overtone Crystal operating at its 8th harmonic at 495 MHz or Channel 18. Other frequencies will work.
  Speaker To Microphone Circuit - Convert
An 8 Ohm Loudspeaker can be used as a Microphone in this speaker to microphone circuit. This circuit will outperform a Microphone Element.
Audio Amplifier Circuit With BandPass
A Very Low Noise Single Stage Audio Amplifier that incorporates a simple RC Bandpass filter on its output.
  Passive Adjustable Notch Filter Circuit
A highly unique offshoot of the Hall Passive Notch filter that provides an adjustable - deep notch between 38 Hz and 86 Hz.
Audio Low Pass Filter Circuit Diagram
An excellent noninverting Low Pass Audio Filter circuit. 4 DB Gain from 300 to 1 KHz. 2 DB Gain at 2.5 KHz and 3DB down at 4.2 KHz.
  741 Active Band Pass Filter Circuit
A fantastic 1500 Hz center frequency active bandpass filter circuit. Uses a dual 9 Volt Power Supply. The chip is a standard 741 IC.
Atomic Microphone - By Pete Zenner
Based on the principal of and Acoustical Resonator, this unit does not need electronics to amplify an audio signal.
  Antenna Circuit, VHF - The Little Sam
A very popular custom made FM/VHF center loaded antenna circuit. Small and for attaching to receivers and or transmitters.
FM Receiver Circuit On A Chip
This FM Receiver Circuit uses a TDA7000 I.C. Chip and operates between 75 to 94 MHz. My friend Pete Zenner asked me to add it.
  Crystal Controlled Transmitter Circuit
This transmitter circuit is history! Used in one of the very first IN-CAR video systems for Police Departments and Federal Agencies across the U.S..
Ultrasonic Voice Transmitter Circuit
A fantastic ultrasonic Voice Transmitter Circuit operating at 40 kHz. Picks up audio and retransmits far beyond the range of human hearing.
  Ultrasonic Voice Receiver Circuit
Point it toward the direction where a ultrasonic voice transmitter circuit is in operation. This unit picks up the 40kHz signal and then converts it to audio.
High Gain Spy Listening Circuit
This High Gain listening circuit is a very sensitive and very powerful Spy Amplifier. It is used in spy or surveillance applications. Dual Microphones.
  Piezo FM Voice Transmitter Circuit
This Piezo transmitter circuit transmits anything and everything, including audio when it is attached to a fixed object. A Fantastic Little Gadget
FM VHF Transmitter Circuit - A6 Adapter
A highly sofisticated FM VHF VFO Transmitter circuit that is used in combination with Pete Zenners Atomic Microphone. Very Powerful.
  Tracking Transmitter Circuit - Simple
A single stage crystal controlled 144 MHz - Simple To Build - transmitter circuit. The circuit uses a 24 MHz crystal and is pulsed at 1 HZ.
FM Transmitter Repeater Circuit - 904
This Transmitter Repeater circuit was originally engineered for Law Enforcement Agencies. Rebroadcast one frequency to another. Super.
  Laser Receiver Circuit - Infrared
This Infrared Laser Receiver circuit uses a 741 IC Chip with any infrared sensor - and the output is fed into any type of audio amp that accepts audio signals.
Electronic Breadboarding - INFO
The Breadboard is the Master Link between a schematic and the finished product. INFO
2 Stage - FM 9V - VFO -Transmitter
A two stage FM 88 to 108 MHz rf transmitter. All layouts, Board, Breadboard and Stripboard.
"Micro" FM 1.5 VFO Transmitter Circuit
All layouts, Board, Breadboard and Stripboard.
Simple FM Transmitter Circuit
A Simple FM transmitter circuit you can find on
the internet that transmits in the FM or VHF band. All layouts, Board, Breadboard and Stripboard.
FM Transmitter Circuit - Very Popular
A circuit that breaks all the records. Has received 917,343 views with 418 comments. All layouts, Board, Breadboard and Stripboard.
FM - Transmitter / Repeater Circuit
This circuit is used to rebroadcast the output of a
CD player, television receiver, or radio receiver to a
distant location in the FM Band. Fantastic!. All layouts, Board, Breadboard and Stripboard.
FM - Snooper Transmitter Circuit
A nifty, single stage circuit is used to pick up both sides of a conversation and then transmit. All Layouts, Board, Breadboard and Stripboard.
Video Transmitter Circuit - FM "Great"
A single stage video circuit that will transmit whatever it's small camera is pointed at to a distant small battery operated TV receiver. All Layouts, Board, Breadboard and Stripboard.
Phone Transmitter Circuit
Telephone / Phone Transmitter clips anywhere along the telephone pair. All Layouts, Board, Breadboard and Stripboard.
FM "Sugar Cube" Transmitter Circuit
The "Original" LOST CIRCUIT of the infamous Sugar Cube Transmitter. It was originally sold in the thousands. All Layouts, Board, Breadboard and Stripboard. A real treasure!
Audio Amplifier Circuit, Mini 2 Watt
A 2 Watt mini audio amplifier circuit suitable for small pocket radios and other portable audio gadgets. Based on Phillips IC TDA 7052.
LM386 Audio Amplifier Circuit
A high quality LM386 audio amplifier circuit using a LM386 IC with output power levels of 300, 500 and 700 millwatts respectively.
LM380N-8 Audio Amplifier Circuit
The circuit is ideal to use as an audio amplifier with other projects you build in your lab like AM or FM receiver circuit, alarm circuit, intercom circuit, etc.
Simple FM Voice Transmitter Circuit
A Very Small and simple one stage ( Adjustable ) FM Voice Transmitter that transmits all sounds to a remote FM adjustable receiver, up to 1.4 mile away.
555 Timer Circuit
The timer starts timing when the switch is turned on. The green LED lights to show that timing is in progress. A great little timing circuit.
DC Power Supply Circuit - Multi Voltage
Experimenters multi power DC supply circuit uses three IC regulators to supply +5, +6, +9, and +12 volts regulated from a nominal 12V supply.
Antenna Amplifier Circuit
An antenna amplifier for the entire VHF broadcast band (100-175 MHz) which can be successfully built without any special test equipment.
Dual Voltage Power Supply Circuit
Shows how to put a dual voltage power supply circuit diagram together. The example shows the hookups. Use the same configuration for other voltages.
Infrared Receiver Circuit
This Unit is a very sensitive Infrared Receiver Circuit. Most any Infrared Phototransistor can be used on the front end. Picks up all forms of infrared.
555 Timer Buzzer Circuit
Here is a very simple to build buzzer circuit using a cheap 555 timer chip. Just close the switch and the unit outputs a tone. The frequency can be changed.
60 Hz Notch Filter Circuit
A very powerful 60Hz active notch active filter using a single 741 chip. Passes all frequencies but suppresses 60 Hz hum around - 28 DB.
Infrared Receiver Surveillance Circuit
A Very Powerful Infrared voice receiver circuit that has Law Enforcement applications for receiving voice transmissions quite a distance without optics.
FM Transmitter Circuit on A Chip
This is one of the first FM transmitter circuits that I engineered back in the late 80's that used an IC 3046 chip.
FM Crystal Controlled Transmitter Circuit
A very professional FM Crystal Controlled Transmitter Circuit that was sold in the thousands to the top agencies in the US.
Ultrasonic Transponder Circuit
This is one of the more complicated ultrasonic circuits that I have engineered over the years. A remote unit triggers An FM Transmitter Circuit
Bug Detector Circuit
A Bug Detector Circuit from H. Adams, a master designer of simple electronic circuits. This circuit uses a MC 34002 chip and a 9V DC battery .
Voice Transmitter Circuit - 200+ MHz
This Unique Voice Transmitter circuit operates between 202 and 230 MHZ, received on any FM Receiver that includes the TV -1 and TV - 2 Bands.
Video Transmitter Circuit - 495 MHz
This Video Transmitter Circuit, is simple to build and operates on Channel 18. It is crystal controlled for absolute stability.