Sunday, September 29, 2013

Battery Equality Monitor

Almost all 24V power systems in trucks, 4WDs, RVs, boats, etc, employ two series-connected 12V lead-acid batteries. The charging system can only maintain the sum of the individual battery voltages. If one battery is failing, this circuit will light a LED. Hence impending battery problems can be forecast. The circuit works by detecting a voltage difference between the two series connected 12V batteries. Idle current is low enough to allow the unit to be permanently left across the batteries.

Circuit diagram:


Battery Equality Monitor Circuit Diagram


R1 = 2.K
R2 = 4.7K
R3 = 39K
R4 = 39K
R5 = 1.5K
R6 = 1.5K
Q1 = BC547
Q2 = BC547
Q3 = BC557
D1 = 3mm Red LED
D2 = 3mm GreenLED
B1 = DC 12 Volt
B2 = DC 12 Volt

Source :

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Friday, September 27, 2013

Drinking Water Alarm

The State Jal Boards supply water for limited duration in a day. Time of water supply is decided by the management and the public does not know the same. In such a situation, this water alarm circuit will save the people from long wait as it will inform them as soon as the water supply starts.

At the heart of this circuit is a small water sensor. For fabricating this water sensor, you need two foils—an aluminium foil and a plastic foil. You can assemble the sensor by rolling aluminium and plastic foils in the shape of a concentric cylinder. Connect one end of the insulated flexible wire on the aluminium foil and the other end to resistor R2. Now mount this sensor inside the water tap such that water can flow through it uninterrupted. To complete the circuit, connect another wire from the junction of pins 2 and 6 of IC1 to the water pipeline or the water tap itself.

The working of the circuit is simple.

Drinking Water Alarm

Timer 555 is wired as an astable multivibrator. The multivibrator will work only when water flows through the water tap and completes the circuit connection. It oscillates at about 1 kHz. The output of the timer at pin 3 is connected to loudspeaker LS1 via capacitor C3. As soon as water starts flowing through the tap, the speaker starts sounding, which indicates resumption of water supply. It remains ‘on’ until you switch off the circuit with switch S1 or remove the sensor from the tap. The circuit works off a 9V battery supply. Assemble the circuit on any general-purpose PCB and house in a suitable cabinet. The water sensor is inserted into the water tap. Connect the lead coming out from the junction of 555 pins 2 and 6 to the body of the water tap. Use on/off switch S1 to power the circuit with the 9V PP3 battery.

Source:w w w. e f y m a g . c o m

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Wednesday, September 25, 2013

Ampere or Current Booster

Small and very useful circuit, Can be built on a veroboard

Volt regulators such as the LM708, and LM317 series (and others) sometimes need to provide a little bit more current then they actually can handle. If that is the case, this little circuit can help out. A power transistor such as the 2N3772 or similar can be used.

The power transistor is used to boost the extra needed current above the maximum allowable current provided via the regulator.
Current up to 1500mA(1.5amp) will flow through the regulator, anything above that makes the regulator conduct and adding the extra needed current to the output load. It is no problem stacking power transistors for even more current. (see diagram). Both regulator and power transistor must be mounted on an adequate heatsink.

Circuit diagram:


R1 = 1R-2W
R2 = 10R-2W
C1 = 35v-470uF
C2 = 35v-470uF
Q1 = TIP2955
IC1 = 78xx Regulator

Source :
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Monday, September 23, 2013

3 3 V or 5 V Direct from the Mains

The SR03x range of voltage regulator chips from Supertex ( connects directly to the rectified mains supply and provides a low-current 3.3 V or 5.0 V output without the need for any step-down transformer or inductor. The circuit requires a full-wave rectified mains voltage input (waveform a). A built-in comparator controls a series-pass configured MOSFET. The MOSFET is only switched on whenever the input voltage is below an 18 V threshold. A 220µF capacitor is used to smooth out fluctuations so that the resultant voltage has a sawtooth waveform (waveform b) with a peak value of 18 V.

3.3 V or 5 V Direct from the Mains circuit schematic

This unregulated voltage is connected to the source input of the chip (pin 7) and an internal voltage regulator produces a regulated output (waveform c) of 3.3 V for the type SR036 or 5.0 V for the SR037. Normally you would expect to see a reservoir capacitor fitted across the output of a full wave rectifier in a power supply circuit but in this case it is important to note that one is not fitted. For correct operation it is necessary for the input voltage to fall close to zero during each half wave.

3.3 V or 5 V Direct from the Mains circuit schematic

This circuit must only be used in a fully encapsulated enclosure with no direct connections to any external circuit. It is important to be aware that the circuit is connected to the mains and the chip has lethal voltages on its pins! All appropriate safety guidelines must be adhered to.
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Saturday, September 21, 2013

1997 Chevy 2500 Pick Up 5 7l engin Wiring Diagram

1997 chevy 2500 pick up 5.7l engin Wiring Diagram

The Part of 1997 chevy 2500 pick up 5.7l engin Wiring Diagram: fuel pump oil pressure switch, fuel
pump prime connector, power distribution cell, fuel pump and sender, dual tanks, fuel pump balance relay, vahicle control module, underhood fuse relay, ECM fuse.
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Tuesday, September 10, 2013

Dual Output DC DC Power Supply for AMOLED Displays

This is a dual-output switch mode power supply reference design based on the MAX17116. The part and reference circuit can provide both negative and positive supplies to AMOLED displays. [via]

Dual-Output DC/DC Power Supply for AMOLED Displays
The MAX17116 includes two current-mode 1.4MHz switch mode power-supply (SMPS) regulators for active-matrix organic light-emitting diode (AMOLED) displays. The positive supply is provided by a step-up regulator with a synchronous rectifier. The negative supply is provided by an inverting regulator with a synchronous rectifier.
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