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This tiny conductivity tester works with LM 3909. The tester makes a beeping sound if the resistance between the test probes between 0 and 100 O lies. Due to the volume of the beep, the resistance between the test probes can be determined. Audio Lm 3909 IC-conduction tester Circuit Diagram Parts List      R1 = 1 k      C1 = 10 uF      C2 = 100 nF      LS = Loudspeaker 12 to 16 Ω      IC1 = LM 3909

Detecting Sound Students often want to use ‘sound’ as an input within electronic projects. Unfortunately sound is not as easy to use as light and temperature, as there is not an instant ‘single component’ solution, as is the case with, for example, an LDR for light or a thermistor for temperature. The main problems with detecting sound are: 1) electret microphone inserts are low cost, but only produce a very small signal, which requires amplification 2) the background noise level can vary considerably, and so some form of calibration is required 3) some noises, such as a hand-clap, are very quick and so can be ‘missed’ with some electronic circuits (e.g. when using a microcontroller) Fortunately these problems can all be overcome at low-cost, by using an electret microphone with three common transistors. The circuit shown in Figure 1 will produce an analogue signal between 0 and 3V that can be detected, for instance, with the analogue input pin of a PIC microcontroller (e.g. 16F876). T...

As electrolytic capacitors age, their internal resistance, also known as "equivalent series resistance" (ESR), gradually increases. This can eventually lead to equipment failure. Using this design, you can measure the ESR of suspect capacitors as well as other small resistances. Basically, the circuit generates a low-voltage 100kHz test signal, which is applied to the capacitor via a pair of probes. An op amp then amplifies the voltage dropped across the capacitor’s series resistance and this can be displayed on a standard multimeter. In more detail, inverter IC1d is configured as a 200kHz oscillator. Its output drives a 4027 J-K flipflop, which divides the oscillator signal in half to ensure an equal mark/space ratio. Two elements of a 4066 quad bilateral switch (IC3c & IC3d) are alternately switched on by the complementary outputs of the J-K flipflop. One switch input (pin 11) is connected to +5V, whereas the other (pin 8) is connected to -5V. The outputs (pins 9 & ...

Attention: This Circuit is using high voltage that is lethal. Please take appropriate precautions This circuit you can convert the 12VDC into 220VAC. The 4047 IC is use to generate the square wave of 50hz. Circuit diagram   How to calculate transformer rating The basic formula is P=VI and between input output of the transformer we have Power input = Power output. For example if we want a 220W output at 220V then we need 1A at the output. Then at the input we must have at least 18.3A at 12V because: 12V*18.3A = 220V*1A, when P1 is 12V*18.3A and P2 is 220V*1A. So  if you have to wind the step up transformer 12V to 220v but input winding must be capable to bear 20A. For this project to produce 220VAC with 500W, we find. Output power is P2 = Output voltage x output current         Output current = 500W/220V                        ...

Nowadays you can buy white LEDs, which emit quite a bit of light. They are so bright that you shouldn’t look directly at them. They are still expensive, but that is bound to change. You can make a very good solid-state pocket torch using a few of these white LEDs. The simplest approach is naturally to use a separate series resistor for each LED, which has an operating voltage of around 3.5 V at 20 mA. Depending on the value of the supply voltage, quite a bit of power will be lost in the resistors. The converter shown here generates a voltage that is high enough to allow ten LEDs to be connected in series. In addition, this converter supplies a constant current instead of a constant voltage. A resistor in series with the LEDs produces a voltage drop that depends on the current through the LEDs. This voltage is compared inside the IC to a 1.25-V reference value, and the current is held constant at 18.4 mA (1.25 V ÷ 68 Ω). The IC used here is one of a series of National Semiconductor ‘sim...

Simple Water Alarm Circuit Schematic .The LM1830 fluid detector IC from National Semiconduc tor is designed to be able to detect the presence of fluids using a probe. This chip requires a relatively high supply voltage and is not the most frugal power consumer. It is also quite specialised so unless you are buying in bulk the one-off price is not cheap.  An alternative circuit show n her e uses a standard CMOS IC type 74HC14. It has the advantage of operating with a 3 V supply and consumes less than 1 µA when the alarm is not sounding, this makes it ideal for use with batteries.  Water Alarm Schematic Circuit Diagram The 74HC14 has six inverters with hysteresis on their input switching thresholds. A capacitor (C1) and a feedback resistor (R1) is all that’s necessary to make an inverter into a square wave signal generator.  In the water alarm circuit the feedback resistor consists of R1 and the water sensor in series. R1 prevents any possibility of short-circuit between t...

The circuit was designed to create a spare and reserve power source with the use of batteries during the absence of power from the mains. BD139 – NPN power transistor used for driver stages in hi-fi amplifiers and television circuits because of its low voltage at 80 V maximum and high current at 1.5 A maximum. Bridge Rectifier – also known as bridge rectifier which has four diodes arranged in a bridge configuration where the output voltage has the same polarity with either polarity of the input voltage.     1N4002 – a 1.0 Amp Silicon rectifier with voltage range of 50 to 1000 Volts and possessing features such as guaranteed high temperature soldering, high current capability, diffused junction, low reverse leakage, utilizes void-free molded plastic technique for low cost construction, and carries Underwriters Laboratory Flammability Classification of 94V-0 by its plastic package. One of the main components in the construction of this circuit is the transformer which ...

Looking for an efficient USB charger that can operate from a 12V car battery? This unit functions at up to 89% efficiency and can charge USB devices at currents up to 525mA. Best of all, it won’t flatten the battery if it's left permanently connected, as long as you remember to unplug the USB device. There are lots of USB chargers on the market but this device has two stand-out features: high efficiency and low standby current. In fact, its standby current is just 160µA, a figure that’s well below the self-discharge current of most lead-acid batteries. This means that you can leave the device permanently connected and it will not cause that battery to go flat (or at least, not much faster than it would of its own accord). Picture of the project: Why is this useful? Well, in September 2009’s “Ask SILICON CHIP” section, D. E. of Ainslie, ACT asked if it was possible to connect a 12V-to-5V USB charger directly to the battery on a motorbike. His reason for wanting to do this is that ...

This is a simple Pre-Amplifier Circuit Diagram . This simple circuit contribute best gain to weak audio signals. use it in front of an RF oscillator to make an RF transmitter that is very sensitive to sound. Best Pre-Amplifier Circuit Diagram

TPA3122D2 Class D Audio Amplifier TPA3122D2 IC is used as a class D audio amplifier and can deliver up to 15W of power at 10% distortions. The real advantage of using a class D amp, especially TPA3122 is the fact that this IC doesn’t need a heatsink because it has a high efficiency. Another great thing about it is that you can buy a $20 built-it-yourself kit or even cheaper from ebay but you need to be careful not to buy a fake one. TPA3122D2 Class D Audio Amplifier I discovered this IC while searching for an audio amplifier circuit that I need for the 2 x 10W/4Ω speakers received from my brother-in-law. I think that TPA3122 can provide enough power for what I need even though it can output only 8W with 1% distortions on a 4Ω speaker (something that some of you might find too low). The main reason I would choose this instead of a class A or B IC is the fact it doesn’t need a heatsink, so the whole amplifier will be lighter in weight and cheaper.

Samsung UN60ES8000 possibly will survive a combination of the penetrating image quality and too the fine box tools.  The Samsung UN60ES8000 permits you a millions of good options with the purpose of you precisely couldn’t carry out or else: Voice Navigation and Gesture management permits you say commands and management tube functions along with your hands, where look Recognition without doubt logs you against your Samsung Apps bill. Samsung UN60ES8000 - 3D Slim LED HDTV Spanking element is with the intention of you just long for watch your favorite films where you browse the muddle otherwise avail yourself of the good center. you’ll be situated able to notice content you like by cataloging on sale shows, movies, and videos across vudu, Hulu Plus, YouTube, and alternative digital content suppliers. Movies are handpicked on behalf of you thru recommendations primarily based on your viewing history and ratings. Access all of your apps and download new to the job ones like Netflix, Fac...

Description This is a portable battery powered USB charger circuit. This circuit is able to charge your PDAs, Ipods, Mp3 players and any device that plug in to a computer USB to charge. If you fit this circuit in a small box with a 9V battery then it will become a portable emergency USB charger. The schematic is so simple using only few components so you can make this circuit in some minutes if all parts available with you. The circuit is using low dropout regulator IC LM7805 which is easily available in the market and it is also very cheap. The circuit takes voltage from 9V battery and step down the voltage in to a DC 5V output.  Circuit Diagram  Source- http://circuitdiagram.org/usb-charger.html

How to Build a 3000W Stereo Power Amplifier Circuit Diagram? Lets start first we define 3000wstereo power amplifier circuit diagram this circuit has a power output of up to 1500W RMS power amplifier circuit is often used to power sound systems spelunker for outdor. In the final image can be seen a series of power amplifiers using 10 sets of power transistors for the ending. This power amplifier circuit using a transistor amplifier from the front, signal splitter, driver and power amplifier. Current consumption required is quite large power amplifier that is 15-20 A 1500W power amplifier circuits for this. Supply voltage needed by the power of this amplifier is the optimal working order symmetrical 130VDC (130VDC-130VDC ground). 1500W amplifier circuit below is a picture series of mono, stereo if you want to make it necessary to make two copies of the circuit. For more details can be viewed directly image the following 1500W power amplifier circuit. The series of High Power Amplifier 15...

Because I’m old school, I wanted to build a Garage Door Closing circuit without relying on integrated configurations (555 timer etc) to keep it simplistic. The circuit closes the garage door after two minutes with C3 and four minutes with the addition of C2. The timer relay is surprisingly accurate (+/- five seconds). Another feature is to ensure that the garage door actually did close, such as if it’s stopped mid-operation by the user. Description: S3 (magnetic N.C.) is located at the garage door and activates the circuit when the garage door opens. RL1 is the reset timer. It’s maintained in the “on” position for two minutes by C3 while the trigger capacitor, C4, is charged. RL2 is the conduit, directing C4 to either RL3 or R1 to ground when off. Purpose of R1 is to prevent arching across contacts and a fast discharge. RL3’s contacts are connected to the Garage Door’s Momentary Switch and is sustained “on”  for a half second by C5. When C3 discharges to the cutoff voltage of RL1, ...

The AT89C51 from ATMEL is the most commonly used variation of the 8051 microcontroller because of the built-in Flash which makes programming / burning very easy. The 8051 has a total of 4 ports for input / output operations which means you can transfer data in or out of the microcontroller through these ports. Let's have a brief introduction to these ports. UPDATE: You can also click this link for an updated version of this post. READ MORE

Build a Square A to Sine Wave Converter Circuit Diagram. This is a simple circuit diagram in this circuit using Two pairs of MOSFETs form a bridge that alternately switches current in opposite directions. Two parallel-resonant LC circuits complete the converter. The Ll/C1 combination is resonant at the fundamental frequency; the L2/C2 combination is resonant at the clock frequency`s third harmonic and acts as a trap.  Square A to Sine Wave Converter Circuit Diagram Tl and C3 ensure that both halves of the MOSFET bridge are never on at the same time by providing a common delay to the gate drive of each half. Select the values of R1 and C3 to yield a time constant that`s less than 5% of the clock`s period. You can add an output amplifier for additional buffering and conditioning of the circuit`s sine-wave output.

Apple has just released a fun commercial to showcase its new line of iPod players and the various colours they come in. The TV spot titled ‘Bounce’, has a bunch of colourful iPod touch, iPod nano and iPod shuffles er…bouncing to music. With all that colour and dancing and bouncing, you may forget that Apple’s latest gen line of iPods has some other awesome features. For instance, the fifth gen iPod touch comes with Siri, 4-inch retina display and an A5 chipset. Maybe the next ad will showcase some of these features with less bouncing.link

Dual Power Supply Circuit For Amplifiers . A power supply suitable for use with the 60W amplifier presented in the predefining project is perfectly simple, and no great skill is required to build (or design) one.  There are a few things one should be careful with, such as the routing of high current leads, but these are easily accomplished. The first thing to choose is a suitable transformer.  I suggest toroidal transformers rather than the traditional "EI" laminated types because they radiate less magnetic flux and are flatter, allowing them to be installed in slimmer cases.  They do have some problems, such as higher inrush current at switch on, which means that slow blow fuses must be used. For the 60W amplifier, a nominal (full load) supply of +/- 35V is required, so a 25-0-25 secondary is ideal - however, see Updates, below.  The circuit for the supply is shown below, and uses separate rectifiers, capacitors and fuses for each channel.  Only the transformer...

The circuit is intended for carrying out harmless experiments with high-voltage pulses and functions in a similar way as an electrified fence generator. The p.r.f. (pulse repetition frequency) is determined by the time constant of network R1-C3 in the feedback loop of op amp IC1a: with values as specified, it is about 0.5 Hz. The stage following the op amp, IC1b, converts the rectangular signal into narrow pulses. Differentiating network R2-C4, in conjunction with the switching threshold of the Schmitt trigger inputs of IC1b, determines the pulse period, which here is about 1.5 ms. The output of IC1b is linked directly to the gate of thyristor THR1, so that this device is triggered by the pulses. The requisite high voltage is generated with the aid of a small mains transformer, whose secondary winding is here used as the primary. This winding, in conjunction with C2, forms a resonant circuit. Capacitor C3 is charged to the supply voltage (12 V) via R3.When a pulse output by IC1b trigg...

Fire alarm can be made with a light sensor (LDR) as in the article with the title of Fire Alarm with this LDR sensor. Principles of fire detection Fire Alarm with LDR sensor is to detect the presence of smoke through the LDR. LDR in the series Fire Alarm does not stand alone in detecting a fire, but the LDR in the pair with the light shining on the LDR. Hence, in the detected smoke from the fire then the intensity of light received by the LDR LDR decreases and eventually trigger an alarm system on a series of Fire Alarm with this LDR sensor. Part 2 that in the series of Fire Alarm with Sensor LDR are some of the sensors, tone generator, audio power. Image Series Fire Alarm with Sensor LDR Function Section of the Fire Alarm with Sensor LDR Part of LDR and light sensor facing to fire smoke detection Part trigger using transistors and regulators as a trigger tone generator 7805 Tone generator section with IC UM66 Power audio section uses an audio power IC TDA 2002 which is equipped with v...

This is a simple Project of 12 V AC Dimmer Circuit Diagram. 12-V AC Dimmer Circuit Diagram The circuit described here is derived from a conventional design for a simple lamp dimmer, as you can see if you imagine a diac connected between points A and B. The difference between this circuit and a normal diac circuit is that a diac circuit won’t work at 12 V. This is the fault of the diac. Most diacs have a trigger voltage in the range of 30 to 40V, so they can’t work at 12 V, which means the dimmer also can’t work. 12-V AC Dimmer Circuit Diagram The portion of the circuit between points A and B acts like a diac with a trigger voltage of approximately 5.5 V. The network formed by R1, P1 and C1 generates a phase shift relative to the supply voltage. The ‘diac equivalent’ circuit outputs a phase-shifted trigger pulse to the triac on each positive and negative half-cycle of the sinusoidal AC voltage. This works as follows. First consider the positive half of the sine wave. C1 charges when the...

Here is a very simple high current power supply circuit . High current power supply can be designed using the LMZ13610 switching power supply circuit . This high current switching power supply electronic project circuit diagram can provide a maximum output current of 10 ampere , using few external electronic parts . Output voltage is fixed and can be set using two external resistors . The output voltage can be set from 0.8 volt up to 6 volt , requiring an input voltage range between 6 and 36 volt . High Current Power Supply Circuit Diagram:   Some features of this power supply electronic circuit diagram are: 50W maximum total output power , up to 10A output current , Input voltage range 6V to 36V , Output voltage range 0.8V to 6V , Efficiency up to 90% , fixed switching frequency (350 kHz) , flexible startup sequencing using external soft-start, protection against inrush currents and faults such as input UVLO and output short circuit , – 40°C to 125°C junction temperature range.

The old nut on our Hofner Colorama II was in a terrible state. It was too shallow and had a piece of card underneath it in order to raise it up. Additionally the bottom was not flat. Here it is: I have no reason to trust this nut at all, so I'm not going to use it as a template for the new one. So here I am sanding a new piece of bone down to the right thickness using a piece of coarse sandpaper set on a flat surface: Then cutting the bone to length: Here I’m checking it fits nicely into the nut slot: Before I can continue, I need to make up a new half pencil, since I appear to have misplaced my old one. So we take a normal pencil: Slice it down the middle (watch your fingers): Superglue the lead into place (optional, but I find it a good idea, since there’s nothing really holding the lead in place at this stage): Remove superglued finger from pencil (again, optional): Sand pencil flat: And then I usually put some Sellotape (Scotch tape) along the bottom of the pencil to stop from ...