Top Circuits Page 187
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Small simple audio mixer with a few components around one FET transistor (2N3819)....
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the gate terminals sensitivity to changes in voltage. The gate terminal here is left open circuit, connected only to the "probe" this being just a few inches of bare copper wire. With no fixed DC biasing, the gate terminal will respond to micro changes in....
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Using a thermistor in the position shown makes a heat activated sensor. A change in temperature will alter the output of the opamp and energize the relay and light the LED. Swapping the position of the< thermistor and 47k resistor makes a cold or frost alarm...
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The simple conjuring trick in Figure 1 is intended to provide some enjoyment for the beginner in electronics or conjuring, and should take only an hour or two to build. The trick works as follows: a wand (with a magnet mounted in one end) must pass in a....
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This circuits allows you to use a cheap loudspeaker as a microphone. Sound waves reaching the speaker cone cause fluctuations in the voice coil. The voice coil moving in the speakers magnetic field will produce a small electrical signal. The circuit is....
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This nifty sound level meter is a perfect one chip replacement for the standard analog meters. It is completely solid state and will never wear out. The whole circuit is based on the LM3915 audio level IC and uses only a few external components....
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Many commercial pest repellers operate in the range of 30 to 50 kHz. My aim was, however, to design a slightly different and somewhat more powerful audio frequency/ultrasonic sound generator that could be used to train dogs. Just imagine the possibilities -....
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This circuit consists of two identical intercom units. Each unit contains a power supply, microphone preamplifier, audio amplifier and a Push To Talk (PTT) relay circuit. Only 2 wires are required to connect the units together. Due to the low output....
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This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone....
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Low distortion bass and treble control for amplifier. Circuit diagram. Electronics projectt....
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This is a very simple, low cost, Hi-Fi quality power amplifier. You can build it 5 ways, like it?s shown in the table (from 20 W to 80 W RMS)....
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Small and interesting circuit that flashes your head lights. Automotive, head lights, circuit diagram. Built around famous NE555 timer circuit....
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This simple circuit can be wired into your headlight switch to provide automatic switching between high and low beam headlights when there is oncoming traffic. Simple electronics project with circuit diagram....
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This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. Electronics project....
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This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with no spikes on the regulated supply.....
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This circuit runs a fast battery test without the need of power supply or expensive moving-coil voltmeters. It has two ranges: when SW1 is set as shown in the circuit diagram, the device can test 3V to 15V batteries. When SW1 is switched to the other....
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The circuit is a microphone amplifier for use with low impedance (~200 ohm) microphones. It will work with stabilized voltages between 6-30VDC. If you don`t build the impedance adapter part with T1, you get a micamp for higher impedance microphones. In this....
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This circuit was designed on request, to remotely monitor when a couple of electric heaters have been left on. Its sensor must be placed in contact with the feeder to be able to monitor when the power cable is drawing current, thus causing the circuit to....
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This circuit was created for digital cameras. It`s known the digital cameras have considerable power consumption. For example my camera Minolta E223 requires approximately 800 mA. In practice a mains power supply or high capacity NiMH accumulators....
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Before you begin a project like this remember: mains voltage is dangerous so if you are not 100% sure of what you ’re doing consult a friend who has the skills or, don ’t do it at all ! If you own a motorcycle, a motor home, a caravan, a lawn mover, a day....
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This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The....
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Information about building a small radio transmitter, which has a PCB 1. 75" x 2. 5" (45mm x 68 mm) and has a range of about 30 yards or so. The documentation with the circuit says the freq range is 100-108 MHz, but I have found it to be more like 85-100....
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This is a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now no longer available. The design is simple and sensitivity and selectivity of the receiver are good. All general....
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The preamplifier offers 20dB in all the region of VHF and it still can reach also their 500MHZ. The amplifier is a circuit of high frequency RF with distinguishable materials. The amplifier as circuit strengthens the tendency of signal with concrete aid,....
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This circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres. I have used a pair of BC548 transistors in this circuit. Although not strictly RF transistors, they still give good results. I have used an ECM Mic insert from....
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This is the schematic for an FM transmitter with 3 to 3. 5 W output power that can be used between 90 and 110 MHz. Although the stability isn`t so bad, a PLL can be used on this circuit. This is a circuit that I`ve build a few years ago for a friend, who....
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The normal telephone bell, at times (specially during night when one does not want to be disturbed), appears to be quite irritating. The circuit shown here converts the loud sounding bell into a soft and pleasing musical tone. The incoming ring is detected....
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While talking to a distant subscriber on telephone, quite often we feel frustrated when the voice of the distant subscriber is so faint that it is barely intelligible. To overcome the problem, circuit of an inexpensive amplifier is presented here. It can be....
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This project is a 3 or more lines mixer. For more than 3 inputs you can repeat the input parts (P=10K R=22K). It powered with 9Vdc....
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If you feel that somebody is tampering with your telephone line you might find this little circuit useful. It detects if there is another telephone connected to the line, if there is a short or an open line. Sound and a flashing light will tell you which is....
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Small telephone bug. Listen telephone line on your FM receiver. It is self powered. Small part count. Circuit diagram, schematics, electronics project....
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It signals that the phone is in use by lighting a red LED. When the phone is not in use, a green LED is lit. It needs no external power and can be connected anywhere on the phone line, even mounted inside the phone. 4. The ring voltage on a phone line is....
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This nifty little circuit lets you record your phone conversations automatically. The device connects to the phone line, your tape recorder`s microphone input, and the recorder`s remote control jack. It senses the voltage in the phone line and begins....
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This version of the Link is for those who really need a good cheap intercom that will work reliably, but without access to an outside Telco line. This could be in a pre school, a hobby farm or a small workshop or factory, where external phone traffic needs....
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Burr-Brown DRV134 AUDIO BALANCED LINE Receiver schematic PCB/Kit anybody? I want to make a Balanced Line RECEIVER using the DRV134. Could anybody....
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Can a 555 negative supply circuit, like the one below I pulled from another schematic, supply enough negative voltage to a LM324 and a AD736JN? I`m....
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This might seem like a dumb question, but I`m a total newb in electronics. I built this preamp to amplify the signal from a small speaker that i use....
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Originally Posted by Pano Like putting milk and sugar in your coffee. Next time by, your Turkish coffee comes with no sugar dave....
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The only downside to a single opamp stage is that it inverts the signal so needs another inverting buffer to put it back again (if absolute phase is important to you). I have seen bunch of schematics with both configurations but I don`t know which one would....
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Hi all, I am very new to this forum as well as DIY electronic circuits. I am not an electrical engineering student nor I have sufficient background (I ....
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So I needed a circuit to act as a bass boost. I ended up adapting this circuit (by ESP Sound) by excluding everything but the 35-150hz part. This....
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Those who`ve scrutinised my PC-board layout very closely, will see that I`ve changed the design slightly from the circuit which I posted a while back. ....
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Originally posted by Justinasia What is the likely cost of the Aleph Ono, all the parts I mean? Anyone know? If it is the same as the Pearl but better ....
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A community dedicated to helping everyone learn the art of audio. Projects by fanatics, for fanatics!....
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Hi to all I`m new in the forum or better I have used it some ago to make a diy projector!I do not know electronics so much (I`m reading books and....
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I done some more playing with the LTspice simulation of Dxvideo`s preamp-with-DC-Servo circuit. I have been using the .four command to have spice....
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Hi all, I am planning to make another LM4702 amp with SAP15 devices (which is published in another topic in this forum). The amp will be in non....
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this LM4702 has found a new home in a Crown DC150 -- for some reason the driver board in the crown was fried but the power supply in good shape:....
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Any thoughts as to how to remove RF from a point-to-point chip amp? I suddenly seem to be picking up a RF signal. It is ever so slight that one must....
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Originally Posted by Neil Davis It`s not a sim. It`s a real measurement from a circuit that has basically the same topology as the Tripath data sheet. ....
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Does anyone know where I can get a schematic for a USB to SPDIF converter, like the ones from empirical audio. Thanks!!! I like their concept but $500 ....
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Can someone enlighten me as to why there is a LC filter on the op amp circuit. And can I do anything to it to improve the sound....
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even if I didn`t read thoroughly nice one almost enough xformers , but certainly not enough shunt regs....
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The Elector Crescendo was my first DIY amp that wasn`t a kit. I borrowed the Elector magasins at our local library and had some `amateur` make the....
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First of all, the circuit is ok, but it`s rather unstable. It varies with temperature, and, for eg, I turned it on and I tune it. Them I switch it..
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Hello, I`m a noob to this forum, and also to circuit design. I`m also interested in a specific project and I thought I`d try to glean a bit of....
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Hi! I have a 4x10"" Ashdown ABM bass cab driven by a Hughes&Kettner bass top. I just had the idea of modifying the bass top to act as a....
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Originally Posted by dscottguitars A rotary 3 position 3 pole switch. In one pole, through a cap out the other pole, no bleeding from one cap to the....
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The schematic here is of the original Music Man Stingray bass guitar preamp. It runs off 9VDC and I have left off the voltage divider part of the....
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There is considerable hiss brought on by the circuit. Cutting the treble knob helps greatly (but no fun with treble cut!). When the vibrato circuit is active, the his is worse. Following these discoveries, I re-capped the board given the schematic values as....
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Hi again, I`ve got a `72 twin reverb on the bench and I`m looking for advice. I`ve never worked with a twin before. This model is silverface, pots and ....
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Hi, can anyone explain what the four transistors on the right hand side of each of McBride`s schematics are doing?....
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Wow. System 7 thankyou so very much for your appreciative response to my Humble creation. My wife would not say i was gifted but Anal to the ooint....
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Tone controls are something of a no-no in high-price audio. But what is a high-price audio cable but a high-price tone control? Now, you can buy or....
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Hello I was, since few months, looking for an easy to build PWM inverter, and without any PIC programing. Looking at a 555 PWM amp circuit, I have an....
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Ohh ok cool, I have forgotten about the -12 supply because my 555 Oscillator doesn?t use a -12 supply, it only uses a +12 and a Ground. You see on my....
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I have designed a simple Electric Guitar SPICE Subcircuit that includes a Signal Generator 440Hz Sine Wave Output at 100mv. The Parameter ""440&quo....
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Hi, I`m working towards an hybrid amplifier where the VAS will be the Aikido, where the OPS is some Emitter-Follower variation. Unfortunately my....
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Originally Posted by tiefbassuebertr Unfortunately I find only RF amplifier devices there (lowest frequency: 10 KHz). It would take the colloquial....
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Originally Posted by shaan Increasing Iq will result in more 4ohm power? Ya I think I understand now. Ya, once I decreased the supply voltage and....
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Apex seems i begin to love this amp the corrected clear schematic is this with different R14 values(tried 22k,30k,56k) and different supply....
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Hi All, I have been trying to come up with a simple soft start circuit that routes power initially through a resistor or thermistor and then activates ....
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I don`t like motor potentiometers, especially if there are cheap and small attenuators but big motors. But big blue alps like ebay item No....
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Hi all, I completed my first amp a few months ago. It was more a test than really something to listen to. It used the 9240/240 Mosfets. Now I want to....
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I used some schematics from Elliot sound products to help with this circuit. L-In and R-In come straight from the speaker terminals, +ve and -ve are +25 and -25 volts from the power supply. When the circuit detects DC, transistor 2 is turned on and the 25....
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Hello, I am new to electronics. It has recently become a hobby. I have built a few guitar pedals and small amps. My project I`m working on now is an....
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Because i cant get help with this in tubes/valves section, i`m opening thread here with HOPE , that SOMEONE whould be able to HELP ME. I need help....
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Dear Susan, your amp is similar to this one which has even a lower parts number. It deserves to be built!....
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Classic 6-Transistor circuit (many variations of this where around in the 1960`s & 70`s), NPN only output devices, fairly high level of Bias, single rail, input and output coupled via a capacitors (electrolytics - no less), clever feedback loop, bootstrapped....
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The amp appears to be unused, still has the plastic film stuck to it. One of the 211`s has a loose component rattling around inside so we will need to get one of those. As I said in my earlier post, it is the possitioning of the 6 smaller valves that we are....
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So there I was, ripping out a solo during a practice on my ""new"" Hammond C2 organ and the sound falls away and gets soft to the point of no....
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Ty- Regarding your updated drawing of the AF/PI stage: - I don`t think R45 exists? - The disk cap bypassng R44 is labeled 68NF750 10% which I assume....
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This is a very nice amplifier design and it is very difficult to improve it. I am glad about the results because that's a very good way to verify my 6DJ8 and 6L6GC Spice models, like I tell you before, the 6L6GC and 807 have very close caracteristics and....
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After much reading and discussion, I think I`ve settled on the plans for an upcoming build for a single-ended 300B integrated amplifier. The circuit....
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Build a preamp that I want to use to take a 1/4" keyboard line level signal and drive a Leslie 147 amplifier with it. I want to build the preamp using a 12AX7 and 12BH7 based on the design of a Hammond Organ preamp. Here is the schematic to the Hammond AO-28....
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Hi everyone, just wondering as I am about to build my first tube amplifier is the attached design o.k. and also does anyone know a suitable....
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I could use some help analysing a circuit. Specifically the frequency cut-off between the bass and treble channels. Is it 500Hz, 1KHz or 5Khz. I`m....