Input and output (I/O) on the Arduino web server using the SD card. Arduino inputs (analogue inputs, switches) are displayed on a web page. Arduino outputs (LEDs) are controlled from a web page. Uses Ajax for flicker free loading....

This is a Very Simple circuit for Lead Acid Battery Charger using PB137 Regulator. The PB137 is used for lead acid battery charger circuit because it can give....

This stroboscope circuit uses 16 high-brightness white LEDs in a torch housing and it provides a signal output to a frequency counter to provide a rev counter display. IC1 is 555 astable multivibrator and it provides a signal to IC2, a 4046 phase lock loop.....

The following diagram is the battery charger schematic for 6V Gel Cell battery type. Component Parts List: R1 = 22 ohm, 1W R2 = 270 ohm R3 = 220 ohm *R4 = 715 ohm, 1% *R5 = 3. 57K, 1% *R6 = 1. 40K, 1% *R7 = 1. 47K, 1% C1 = 0. 1 F, ceramic C2 = 0. 1 F,....

The circuit below will trickle charge a four cell pack of AA or AAA NiMH batteries. The circuit draws current from the +5v available a USB connection and pumps about 70ma of current into the battery. This should be enough current to fully charge a pack of....

Operating a stepper motor using a fixed (constant) voltage supply results in poor torque at high speeds. In fact, stepper motors tend to stall at fairly low speeds under such conditions. Several approaches can be used to overcome this problem, one of which....

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This stereo FM wireless microphone also makes a great quality audio link. We tested it to beyond 50 meters and it was rock solid. It`s certainly not the first wireless microphone we`ve ever published but this one is a little different. It`s stereo, providing....

Most off-the-shelf car battery chargers cannot not be left connected to the battery for long periods of time as over-charging and consequent battery damage will occur. This add-on circuit is placed in series with the battery being charged and is powered by....

Powering the system is required by many applications while charging the battery simultaneously. Interaction between the system and charger may result in a....

Processor based systems usually require a voltage supervisor chip to produce a clean reset pulse to the processor whenever a brown-out` condition of the power supply is detected. More complex designs employing multiple power supplies can be unreliable if....

This circuit charges two NiCad cells with a constant current and features dual charging rates, voltage cutoff and an audible alarm. The circuit is powered....

48 V phantom` powering has become the standard for professional condenser microphones. The supply (or rather bias) voltage is applied over both wires of the balanced screened cable via two 6k8 resistors (see reference [1]) the absolute value is not critical,....

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In this tutorial you will build a wailing siren that plays a tone that increases and decreases in pitch. The circuit uses two 555 ICs and a loudspeaker....

Most LED driver circuits use a series resistor to control the current through the LED. For applications needing a few LEDs, this is optimal. However, for applications needing many LEDs, this becomes extravagantly inefficient and it is tempting to keep the....

An old Nokia phone charger with 5. 6 V output, so I tried to adjust it to 12 V. By changing the Zener diode though I manged to do that, but I can`t understand its circuit (I replaced the 9v1 with 16v Zener). I would really appreciate any help to understand....

This circuit requires a regulated 10V-DC front end capable of supplying 2 Amps. Begins the charge period at 240mA and at full charge switches automatically to a float condition (trickle charge) of 12mA. The capacitors should be the ceramic 50V (or greater)....

This circuit was intended to be used as a separate, portable unit, to signal by means of a LED when the output wave form of a particular audio stage is "clipping" i. e. is reaching the onset of its maximum permitted peak-to-peak voltage value before an....

The above circuit will charge any 2-cell * Li-Ion battery pack. Maximum current is about 650 milliamps. The circuit is designed for batteries of 900mah or higher. Note this circuit is NOT for Li-Metal batts (i. e. Duralites). Power source can be a 12v Gell....

Regardless of whether you want to effectively imitate a house fire, a campfire, or light from welding, the circuit described here fills the bill without using a microcontroller, although it does use a larger number of components (including some truly....

The circuit uses ACpositive half cycle charge. Charging speed is fast and it can extend battery life. People use the charger on ordinary motorcycle. It has an excellent performance and saves 5% fuel. It is a practical charging circuit. Working principle:....

A oscilloscope would be useful in analyzing the waveforms produced by this circuit, but it is not essential. An audio detector is a very useful piece of test equipment for this experiment, especially if you don`t have an oscilloscope. The "555" integrated....

This circuit could be used (depending on your circumstances) by a gentleman to summon his butler, a manager his secretary or as in the author`s case to call the kids down to dinner without having to shout above the level of the CD player/TV/games console in....

If you forget to switch off the light after leaving a seldom used room (such as the loft), there`s a strong likelihood that it could remain lit for months, running up an expensive power bill in the process. How can we prevent this waste It`s not hard for....

A simple NiCd charger can be built using junk box` components and an inexpensive LM317 or 78xx voltage regulator. Using a current limiter composed of R3 and a transistor, it can charge as many cells as desired until a fully charged` voltage determined by the....

First off I should mention that this is supplemental Instructable to the countless others that show you how to build a USB charger. I am assuming you....

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....

As suggested before, it is beneficial to be able to adjust the gain of the amplifier circuit without having to change more than one resistor value, as is necessary with the previous design of differential amplifier. The so-called instrumentation builds on....

L200 Power Supply Regulator There are applications in which it is important for the supply voltage to be largely independent of the level of the....