Circuit Diagram

Zero beat Metal detector

Published:2012/9/13 21:08:00 Author:Ecco | Keyword: Zero beat, Metal detector

This is the design circuit for a sensing the metal. Metal detectors have two oscillators. One is tunable and the other is Fix with a loop. Both are Tuned at same frequency. Outputs from this two oscillators are then mixed in a mixer which produces only the difference. Means, if both oscillators are at the same frequency, there is nothing heard in the speaker. This is the figure of the circuit. Source: NEXT.GR   (View)

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Beat Balance Metal Detector

Published:2012/9/13 21:07:00 Author:Ecco | Keyword: Beat Balance, Metal Detector

Various embodiments of the BB metal detector have been published, and it has been widely described in the press as a new genre. Instead of using a search and a reference oscillator as with BFO, or Tx and Rx coils as with IB, it uses two transmitters or search oscillators with IB-style coil overlap. The frequencies of the two oscillators are then mixed in similar fashion to BFO, to produce an audible heterodyne. On the surface of it, this design would seem to represent little more than a twinned BFO metal detector. Source: NEXT.GR   (View)

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Small Metal detector schematic circuit

Published:2012/9/13 21:07:00 Author:Ecco | Keyword: Small Metal detector

This metal detector circuit needs to be powered using a 9 volts power supply ( DC) or a 9 volts battery . The C1 capacitor is a variable capacitor with a value of 365 pF , C2 is a 100pF silver mica capacitor , C3 is a 0.05 uF disc capacitor and the C4 is a 4.7 uF capacitor . The Q1 transistor can be RCA SK3011 npn transistor or equivalent type and all resistors need to be ? watts. Source: NEXT.GR   (View)

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BFO metal Detector Circuit

Published:2012/9/13 21:07:00 Author:Ecco | Keyword: BFO, metal Detector

By adjusting the oscillators so their frequencies are very nearly the same, the difference between them is made audible as a beat note, this beat note changes slightly when the search loop is moved over or near to a piece of metal. It has been found in practice best to make the search oscillator fixed say at 100khz and to arrange for the reference oscillator to be adjustable 100khz plus or minus 250hz. This gives a beat note of 250hz to 0 to 250hz. The beat note disappears or nulls when the two oscillators are about equal. This type of detector is most sensitive when the beat note is close to zero, about 5hz ( motor boating ) any slight change being noticeable. Source: NEXT.GR   (View)

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BFO metal Detector Circuit with IC 4093

Published:2012/9/13 21:06:00 Author:Ecco | Keyword: BFO, metal Detector, IC

The circuit incorporates two oscillators, both operating at about 40kHz. The first, IC1a, is a standard CMOS oscillator with its frequency adjustable via VR1. The frequency of the second, IC1b, is highly dependent on the inductance of coil L1, so that its frequency shifts in the presence of metal. L1 is 70 turns of 0.315mm enamelled copper wire wound on a 120mm diameter former. Source: NEXT.GR   (View)

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Bifilar oscillator metal detector

Published:2012/9/13 21:05:00 Author:Ecco | Keyword: Bifilar oscillator, metal detector

Its performance is not comparable to more advanced commercial products, of course, but it still works. Anyway, during WWII metal detectors based on the same principle were utilized my combat engineers of many armies to clear mines. The main idea is really quite simple: build two identical oscillators and adjust them to the same frequency. One of the oscillators uses the search coil while the second one incorporates a variable inductor. When both are operating at the same frequency, the output is zero. If the search coil moves near any metal, however, frequency of the first oscillator shifts and an audible tone is heard in the headphones. Source: NEXT.GR   (View)

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Mini metal detecror (colpitts oscillator)

Published:2012/9/13 21:04:00 Author:Ecco | Keyword: Mini, metal detecror, colpitts oscillator

The circuit uses two CMOS IC’s IC1 uses inverters connected as a Colpitts oscillator of 100KHz; the LC frequency determining elements being the search coil and parallel resonating capacitor. An 80 turn close wound 30swg 100mm diameter coil will fit inside the CD case. I will leave the choice of the IC to the reader: this can be any of the well known CMOS inverters or NAND, NOR gates etc configured as an inverters. The choice is yours, use whatever you have on hand. IC2 can be either 74C00 or 4011 quad NAND gates. Source: NEXT.GR   (View)

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Simple Metal Detector

Published:2012/9/13 21:04:00 Author:Ecco | Keyword: Simple , Metal Detector

The Meter and other small circuit differences, gives better performance. On the Schematic, I show Two Possible Coils. 1) The Ferrite Rod, creates an Accurate Pin Point. But it also has a Very Narrow Detection Field. 2) The Dual Wound Tesla Coil Creates a Wide Field of Detection. With Maximum Sensitivity at the Center of the coil. Detection of metal is with a Meter and LED. The Meter Gives a Much Better Sensitivity. Source: NEXT.GR   (View)

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TV and FM jammer schematic

Published:2012/9/13 20:59:00 Author:Ecco | Keyword: TV, FM jammer

The Jammer is a very small circuit and can fit inside a small plastic box with 9V battery inside. It can be very illegal if you attach an external antenna so don't. adjust frequency by turning trimmer. Source: NEXT.GR   (View)

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FM radio with TDA7000

Published:2012/9/13 20:58:00 Author:Ecco | Keyword: FM radio

An FM radio on a single chip requiring only a few simple peripheral components. In particular the ship requires only one simple coil and alignment is very easy. The chip includes an RF input stage, mixer, local oscillator, IF amplifier/limiter, phase demodulator, mute detector and mute switch. The output will directly drive a crystal earpiece or could be used with a TBA820M to form a complete portable radio. Source: NEXT.GR   (View)

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1W Linear FM Booster

Published:2012/9/13 20:55:00 Author:Ecco | Keyword: 1W, Linear FM Booster

That RF Amplifier is for boosting small fm transmitters and bugs. It use two Philips 2N4427 and its power is about 1Watt. At the output you can drive any linear with BGY133 or BLY87 and so on. Its power supply has to give 500mA current at 12 Volts. More voltage can boost the distance but the transistors will be burned much earlier than usual.! In any case do not exceed the 15Volts. Source: NEXT.GR   (View)

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1W stereo Headphone Amp (TDA2822)

Published:2012/9/13 20:54:00 Author:Ecco | Keyword: 1W , stereo Headphone Amp

A stereo power amp designed for use in portable players and radios. A 3V supply can be used to drive headphones providing 20mW in 32 Ohms per channel. Source: NEXT.GR   (View)

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Water Softener Circuit

Published:2012/9/13 20:53:00 Author:Ecco | Keyword: Water Softener

That circuit is based at a technique to remove or neutralize the salt in water, and protect the pipes at home as well as the washing machines or our selves from salt. Its called water softener and its automated circuit using two 555 timers. Source: NEXT.GR   (View)

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2 Watts FM transmitter

Published:2012/9/13 20:52:00 Author:Ecco | Keyword: 2 Watts, FM transmitter

This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter, L2= 1 turn - 10mm diameter. R9 trimmer controls the modulation gain. The tunning is easy by controlling C9 trimmer (88-108 MHz). The RFC J should be the VK220J with ferrite (VK200 is not suitable). Source: NEXT.GR   (View)

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50W Hi-Fi amplifier with TDA7294

Published:2012/9/13 20:51:00 Author:Ecco | Keyword: 50W, Hi-Fi amplifier

The TDA7294 is a Hi-Fi amplifier and can give 100W RMS but with 10% distortion. Supplying 30 Volts you can have 50 Watts RMS with 1% distortion. Frequency range start at 16Hz and can reach 100KHz. Make sure you are using good heatsink. The chip supports mute function as well. Source: NEXT.GR   (View)

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FM surveillance BuG Transmitter

Published:2012/9/13 20:50:00 Author:Ecco | Keyword: FM surveillance BuG , Transmitter

The Circuit shown can transmit voice to exceptionally good range. Tune trimmer to hear the signal to your near radio. Frequency range is 88-108 MHz. Max current consumption is 30mA. You can power the bug with a 9Volt Battery, or you can plug a power supply to feed in 9-12 Volts. Source: NEXT.GR   (View)

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TV and FM jammer schematic

Published:2012/9/13 20:45:00 Author:Ecco | Keyword: TV, FM jammer

The Jammer is a very small circuit and can fit inside a small plastic box with 9V battery inside. It can be very illegal if you attach an external antenna so don't. adjust frequency by turning trimmer. Source: NEXT.GR   (View)

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In-Car lights delay circuit

Published:2012/9/13 20:39:00 Author:Ecco | Keyword: In-Car lights, delay circuit

This circuit switch slowly on and off the internal lights in a car. The delaying time can be adjusted changing the values of the 10k, 4M7 resistors and capacitor. Source: NEXT.GR   (View)

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Amplifier input signal overdrive auto-protection

Published:2012/9/13 20:39:00 Author:Ecco | Keyword: Amplifier input, signal overdrive , auto-protection

That circuit protects the overdriven signals going into an amplifier. Instead of a zener diode we use a transistor. That way we ensure that the above the ordinary input voltages ( 1 volt r.m.s.) can be acheaved without distortion. Also the use of a transistor limits the number of components used in this schematic. Source: NEXT.GR   (View)

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Passive subwoofer filter

Published:2012/9/13 20:38:00 Author:Ecco | Keyword: Passive subwoofer, filter

The schematic shown, does no need any power supply because is a simple low frequency passive filter. It could be usefull if you want to drive an extra subwoofer from your stereo system. Source: NEXT.GR   (View)

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