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Pressing the switch while a dual LED is green advances you to to the next stage; but mess-up and press while red, and you go back to the beginning. It can be tricky and a challenge. Fun and teaches some practical basic electronics. Operates on 9V battery.

Three Digit Counter Module 
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An event counter; this economical counter module may be ganged for six or nine digits. Has count and reset switches with debounce built-in. Operates on a nine volt battery. This is a two board kit with the count and reset switches along with the debounce circuitry on one board, the LED digits and circuit on another.

Introduction to a Power Supply Kit 
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A practical battery eliminator for circuit projects at the bench. This is a basic power supply using two ICís (7805) regulators. User needs to supply a transformer up to 20V AC for input (we suggest scrounging from old radio or surplus catalog). Outputs are regulated, one variable up to 28 volts and one constant 5V DC. A good introduction to power supplies.

FM Stereo Transmitter 
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This is a circuit that will broadcast CD quality sound to your FM Walkman, home stereo or automobile radio. It produces a strong signal that will generally cover the average home and yard. It is stable enough to use even with digitally tuned FM receivers. Typical uses include broadcasting your own music to a receiver at pool-side or in the garden. Or, you could broadcast from a personal, portable CD player to a car radio that has no CD player. School uses include running a "broadcast station" from another room as a speech class exercise. The unit is powered by a 9V transistor battery, or you could use an AC wall adaptor.

3 Volt FM (miniature) Transmitter 
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The most powerful circuit weíve seen that operates on such low voltage (just two AA cells). A range of 100 meters can be expected and given a good antenna and good conditions, 500 meters is not unusual. Can be operated on up to about 9 volts. Transmits to the FM radio band. Teaches basics of transmitters. Microphone is included.

Light Alarm 
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A sensitive photo Darlington transistor is used with CMOS NAND gate. The circuit detects light and triggers a siren. You could add your own triac or relay and switch practically anything. The kit uses the MEL12 Darlington super-alpha phototransistors, typically about ten times more sensitive than a normal phototransistor. The circuit usage includes burglar alarms, medicine cabinet alarm, automobile trunk alarm etc..

Oscillator Building Blocks 
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Build and experiment with astable, monostable and RS flip-flop multivibrators on one PC board with six LEDís. See and understand exactly how each works. This is a very educational kit and an excellent introduction to electronics. Operates on 9V battery.

Touch or Contact Switch Kit 
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Both a touch and a contact switch are built onto one PC board so that the builder can see how each works. A battery can power the contact switch but youíll need an AC power supply for the touch switch to work well (use No. 80-040) for reasons explained with the kit. (The circuit is triggered by AC "hum" , so use a wall wart power supply for best result.) The circuit switches a relay with a 3 amp, 110 volt rating. Use to switch lamps, other appliances.

Home/Car Alarm  
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This circuit is an alarm for the home or car door, and a lot more. It employs a magnet and reed switch to trigger the circuit; when the magnet is moved away from the reed switch, the alarm is triggered.  An integral piezo sounder produces the alarm sound (100dB). And a PLUS, a relay capable of handling up to 10 amps AC is included and  may be connected to turn on or off an appliance, light or external alarm sounder etc. Therefore the circuit could be used to turn on a light whenever a basement or garage door is opened.

Universal Timer 
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Set timer for anywhere from a few seconds to about 15 minutes, control AC appliances; it will beep and trigger a relay when it has timed down. May be used for darkroom or PC board exposure timer, exit room timer etc.. Turn anything on or off. The ten amp relay can switch some larger  loads such as bright lights, small AC motors etc. The circuit operates from 9 volt transistor battery.

Photo Sensor with Control Relay 
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The most popular usage for this kit is to make your own nightlight; and you won't be limited to one of those dinky seven watt bulbs. You could also switch just about any appliance, either on or off, with either darkness or daylight. Light sensitivity is adjustable over quite a range. The relay can handle up to 10 amps AC. You need to add a nine volt transistor battery or a nine volt, 25 mA supply

Stereo Preamplifier 
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Amplify any tiny audio signals about fifty times, and deliver them to a power amplifier cleanly and undistorted. An AGC (automatic gain control) eliminates pops or distortion. This circuit will be useful in boosting the output from tape heads, microphones or a magnetic phono cartridge etc.. The fidelity is very good; use for input to an audio amplifier. Requires a 12V DC power supply at about 100 mA peak.

Voice Changer 
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Your voice can be changed to add a vibration, like those used to disguise secret witnesses. Or, you may change your voice tone upward or downward; women sound like men and vice versa. Includes a very ROBOTIC voice as well. A microphone and speaker are included on the PC board, all that you need to add is a nine volt, transistor battery. This is a very novel and entertaining circuit.

Sound Effects Generator 
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Another novel circuit, that might be useful for special theatrical effects. Or, if you are simply a practical joker. The circuit can produce sounds such as the tick-tock of a grand fatherís clock, a heart monitor (as in the hospital), water on a tin roof, a motor boat, cricket, etc.. Requires a 9 volt battery. Includes its own speaker.

Unipolar Stepper Motor Driver 

A stepper may be used to orient a video camera, antenna, spotlight etc.. or used for table position in production. This driver will control a 5, 6 or 8 lead unipolar stepper motor (often available from surplus dealers). The circuit permits fast or slow run rate and even single stepping into final position; uses the UCN5804B IC. Four LEDís indicate movement if motor is remotely controlled (input from 6 to 35 volts). The kit is supplied with quite a bit of good information, how to identify motor connections, spec sheets and a list of references for reading about steppers etc.

Sound Activated Switch for Tape Recorder 
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Turn on any tape recorder that has a remote on/off jack (most cassettes). The circuit has a feed back and delay circuit for robust operation. You could add a relay for switching heavy loads; and tape recorders are not the limit. How about turning on lights via voice or a whistle? Circuit switches off after six seconds of silence.

FM Telephone Transmitter 
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Miniature transmitter attaches to the phone line and transmits the conversation. Transmits 200 yards and more in most installations. Tunable to clear spot on the FM band of your radio. Completely parasitic; i.e. uses the power from the telephone line and needs no battery. The circuit might be used to share or record conversations, but please do not use illegally.

Xenon Tube Flasher (6 volt) 
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Bright, variable flash rate strobe light can serve as a beacon, signal etc.. A small circuit, easily transported for camping. Uses could include photography, spooky fun house etc.. (Try turning it on with the VOX switch No. 80-130). Flash rate may be varied to between 1 and four flashes per second.

Ultrasonic Movement Detector  
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The circuit uses a matched pair of 40Khz transducer elements to detect movement out to about 22 feet. You may add a relay (not included) to switch a heavy appliance etc.; the unit switches just an LED as supplied. The circuit can be switched to latch "on". An ideal alarm circuit that cannot  be easily fooled.

OpAmp Function Generator 
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A very low cost and simple circuit to generate square, pseudo-sine wave and triangular waveforms in the audio frequency range. Uses a quad OpAmp type LM384. This is an educational kit and recommended to instructors and to the person wanting to understand electronics more thoroughly.

One Watt Audio Amplifier (monaural) 
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While one watt is plenty for personal use (most small radios that have speakers produce less than1/4 watt) the size is quite small and easy to fit into a case with other projects. Battery operated from 3 to 15 volts, six volts is optimum.  You can amplify your other kits, a radio etc. Output into an eight ohm speaker. The PC board is just 1-13/16" square; tallest component about 5/8" tall.

Sound Activated FM Transmitter  
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Sound turns on the transmitter, which might be a good way to hear a baby waking up. The transmitter can be monitored with any FM radio, Walkman etc. Simply tune the receiver to a clear spot on the FM band (between 88 and 108 MHz) and then tune in the transmitter.  A neat way to catch a thief in another room or garage. The volume of sound needed to trigger the circuit is adjustable; can be set to very sensitive pickup.. The two stage transmitter has good range and the circuit powers down unless it "hears" sounds; reactivates with a sound.

Electronic Combination Lock 
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This really is an excellent introduction to electronic security systems. Set your own four digit code, a wrong sequence simply resets the lock. The correct code will activate a relay that can handle up to 240 volts AC. The nine digit key-pad is on a separate board connected to the circuit via a ribbon cable (30"), so a variety of mounting ideas is possible. Requires a 9 or 12 volt battery or supply.

9 Volt Siren 
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A simple circuit with a lot of output. Uses a voltage controlled oscillator; and includes a half watt speaker. Connect it to an alarm system, sound switch or whatever you dream up. Produces the loud rise-and-fall of typical siren.

9 volt battery operation.

Two-Stage FM Transmitter, or wireless Microphone 
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A powerful little circuit with surprisingly good audio quality. Can transmit up to about 1/2 mile in open country. This is probably the most powerful FM transmitter that you can legally purchase. An electret microphone is used to add sensitivity. The circuit can run on six volts, greatest output is at 12 volts, but use 9 volts and short antenna wire to stay legal.

5 LED Multi-Sequential Flasher 
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Flashes five, very bright LEDís in any one of seven,  user selectable, patterns. A COB (chip-on board) IC  makes assembly very easy; the chip is supplied pre-mounted on its own board and a motherboard contains the entire circuit. Operates on 3 volts DC, battery holder is included. Continuously repeats a sequence when power is applied.

8 Watt Audio Amplifier 
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Low voltage operation does not mean low-power. This amplifier can produce  a full eight watts into a standard four or eight ohm "load", such as a speaker. Actually, it can deliver up to 11 watts if you use a 16 volt supply. You may use this amplifier with a wide range of power supplies, from 5 volts to 20 volts. The IC has built-in current limiting and over-heating protection. An ideal building block for use with many other projects. The audio quality is excellent.

5 LED Sequential Flasher 
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 The circuit flashes five LEDís in sequence repeatedly until you turn it off. Flash rate is user adjustable. The circuit uses an IC chip-onboard which you will then mount on the included motherboard; battery holder is included. Powered by a 3 Volt supply or battery; good for a childís toy or for those "high-tech" looking special effects for stage plays etc.

ION Generator 
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Are there some healthful positive benefits caused by being in an environment that contains negative or positive ions? Some reports suggest a wide range of benefits. This generator can be set up to generate either negative or positive ions; the builderís choice. Operation is from 117 Volts AC power line. You will need to find a case or box for the final assembly, about 2" x 4-1/4" and an inch depth; and an AC power cord from an old lamp (or buy new). You can actually feel the flow of ions from the unit.

One Chip AM Radio 
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This is a complete AM radio for the standard broadcast band, most of which is on a single IC. Other components, such as the coils and variable capacitor to make a finished radio, are included. The IC is the RF amp, detector and AGC circuitry. The ICís output drives a two stage, transistor audio amplifier and 3" speaker. Operates from 9 volt battery. A good kit for beginners to see and build.

DC Motor Speed Controller 
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 Vary the speed of DC motors the very best way with this kit. Gear boxes can be costly and series resistors may cause stalling. This circuit delivers the voltage to the motor with pulses and the speed is controlled via pulse width modulation (PWM). The speed control is a potentiometer, for DC motors up to 100 Volts at a maximum of five amps.

Variable Power Supply 
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A very basic power supply that can be adjusted over a range of about 1.5 to 35 volts DC. If you add a heat sink (included), you can run it as "hot" as 2 amps output; otherwise about 60mA @12 volts. This is a text book circuit using an LM317, which is a 3 terminal regulator in a TO-220 package. Input can be either AC or DC; DC input must be at least 2.5V above the required voltage output. You could use a surplus transformer from 12 volts up for input

PIC (programmable IC) PROGRAMMER 
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An entry level programmer and terrific educational aid. The 16C84 micro-controller from Microchip Technologies has become very popular with hobbyists and beginners. Does not require U/V light to erase programs; programs are erased electrically and the chip used repeatedly. This kit includes all software and hardware needed to begin programming; a full manual is on disk. Connects to an IBM-PC parallel port, connector included. Nine volt transistor battery operation.

Four Train Sound Effect 
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Ideal for model railroads; produces the whistle, train chugging sound, crossing bell and the Ďclickety-clack of crossing a bridge.

Ambulance, Fire and Police Sounds 
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Sirens and machine guns and more; great for kids toy!

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Our audio amplifier kit works very well, but if your input is a tape head, magnetic phono cartridge or electric mike, the input level may be too low to do the job. This small preamp can be used in these applications; plus, we have included a mike that may be used with the circuit. Power at 6V to 12V (current at 12V is 3mA, only 2mA at 9V). The gain is more than 40 dB.



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