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Showing posts with label battery. Show all posts

Saturday, April 13, 2013

12 Volt Battery Guardian

Dont get caught with a flat battery; this easy-to-build circuit can cut off the energy to a 12V fridge or automotive stereo device if the battery voltages drops beneath critical level. Electric fridges in trucks and 4 wheel drives are a actually perfect idea but if you're not automobileeful, they are able to severely discharge the battery and go away you stranded. Maybe the battery will end up with extreme injury as well. The same downside applies when you have an important stereo gadget and you like to play it without the motor running.

Main characteristics:

Cuts power to load (eg, fridge) when battery voltage drops under a preset stage.
10A rating.
Low energy drain.
Chirping sound throughout cut-out.
Flashing LED indication all through cut-out.
Automatically reconnects energy when battery recharged.

Operation on 12V is fine when the motor is working and battery cost is maintained but if the fridge is allowed to run for too lengthy when the motor is stopped, it could neatly flatten the battery in a slightly short time. This is where the Battery Guardian comes into play. It displays the battery voltage and disconnects energy to the fridge sooner than the battery develop intos too flat to allow the engine to be began again.

Parts layout:

PCB layout:

Circuit diagram:

Source: Silicon Chip 6 May 2002

Battery Discharger Using Discrete Components

The battery discharger revealed on this web site may be greater with the help of including a Schottky diode (D3). This be certains that a NiCd cell is discharged to not 0.6–0.7 V, but to handiest beneath 1 V as really helpful by means of the producers. An additional impact is then that gentle-emitting diode D2 flashes when the battery related to the terminals is ﬂat. The circuit in the diagram is in protecting with an astable multivibrator operating at a frequency of about 25 kHz. When transistor T2 habitss, a present go with the flows by means of inductor L1, whereupon energy is saved in the resulting electromagnetic container. When T2 is cut off, the ﬁeld crumples, whereupon a counter-emf is produced at a level that exceeds the forward voltage (about 1.6 V) of D2.

$\"Battery$

A present then ﬂows throughout the diode in order that this milds. Diode D1 stops the present ﬂowing via R4 and C2. This course of is halted only when the battery voltage not provides a enough base attainable for the transistors. In the original circuit, this came about at about 0.65 V. The addition of the ahead bias of D3 (about 0.3 V), the ﬁnal discharge voltage of the battery is raised to 0.9–1.0 V. Additional resistors R5 and R6 ensure that enough present ﬂows by D3. When the battery is discharged to the recommended degree, it have to be removed from the discharger considering, unlike the original circuit, a small current continues to ﬂow by D3, R2-R3, and R5-R6 until the battery is fullly discharged.

The flashing of D2 when the battery is nearing beneficial discharge is due to the rising interior resistance of the battery decreasing the terminal voltage to beneath the threshold level. If no current ﬂows, the interior resistance is of no final result since the terminal voltage upward pushs to the threshold voltage with the aid of taking some vitality from the battery. When the discharge is complete to the recommended stage, the LED goes out. It will have to subsequently be mentioned that the battery is discharged adequately when the LED commences to ﬂash.

http://www.ecircuitslab.com/

Friday, April 12, 2013

USB Battery Charger Circuit Rise

In recent 12 monthss, the utilization of USB or Universal Serial Bus as a reliable communiques interface in lots of digital instruments have increased because of its increased pace, size and flexibility. It essentially consists of terminals VBUS(+5V provide), GROUND, D+ and D-. As a complete lot of of the devices run on rechargeable battery, it is now the development to design the charging circuit that makes use of the energy supply from the USB port to charge the rechargeable battery. This function will make the instruments more handy to the users as the tools will get their energy from the bus and requires no outside plug or cables.

USB Bus Powered Functions

Theres essentially three lessons of USB performs on power that can be derived from the port.

High-Power Bus The excessive energy bus energyed operates derived all its power from the VBUS and cannt draw over 100mA unless its been configured. One time configured, it would possibly probably draw as a lot as 5 unit loads(500mA) by using asking for it in its descriptor. At full load, it must have the flexibility to work between the VBUS voltage of 4.75V and 5.25V.

Low-Power Bus The low energy bus energyed operates derived all its power from the VBUS and should now not draw over one unit load (100mA) in line with the USB usual. It should even have the flexibility to work between the VBUS voltage of 4.40V and 5.25V.

Self-Power Self power performs can draw up to 100mA from the VBUS and the remaining from its outdoor source. This is the easystst to design.

USB Port Powered Battery Charger

This utility circuit makes use of the MCP73853/MCP73855 linear cost management controllers for value delicate utilitys. They are in particular designed for USB softwares and cling to the entire USB specs governing the USB power bus. The circuit below makes use of the MCP73855 to design a USB energyed Lithium Ion/Lithium Polymer battery costr through deriving the energy from the USB port.

5v Powered Charge Pump Battery Charger

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 2500ma-hour cells in about 36 hours. The circuit uses a single 74HC14 hex Schmitt trigger inverter in conjunction with a voltage doubler charge pump circuit.

Monday, March 25, 2013

Battery powered Headphone Amplifier

Low distortion Class-B circuitry 6V Battery Supply

Some lovers of High Fidelity headphone listening prefer the use of battery powered headphone amplifiers, not only for portable units but also for home "table" applications. This design is intended to fulfil their needs and its topology is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-B arrangement. Output power can reach 100mW RMS into a 16 Ohm load at 6V supply with low standing and mean current consumption, allowing long battery duration. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability.

Battery-powered Headphone Amplifier Circuit diagram

Notes:

For a Stereo version of this circuit, all parts must be doubled except P1, SW1, J2 and B1.
Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to maximum resistance and Trimmer R3 to about the middle of its travel.
Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output.
Switch on the supply and measure the battery voltage with a Multimeter set to about 10Vdc fsd.
Connect the Multimeter across the positive end of C4 and the negative ground.
Rotate R3 in order to read on the Multimeter display exactly half of the battery voltage previously measured.
Switch off the supply, disconnect the Multimeter and reconnect it, set to measure about 10mA fsd, in series to the positive supply of the amplifier.
Switch on the supply and rotate R6 slowly until a reading of about 3mA is displayed.
Check again the voltage at the positive end of C4 and readjust R3 if necessary.
Wait about 15 minutes, watch if the current is varying and readjust if necessary.
Those lucky enough to reach an oscilloscope and a 1KHz sine wave generator, can drive the amplifier to the maximum output power and adjust R3 in order to obtain a symmetrical clipping of the sine wave displayed.

Technical data:
Output power (1KHz sinewave):
    16 Ohm: 100mW RMS
    32 Ohm: 60mW RMS
    64 Ohm: 35mW RMS
    100 Ohm: 22.5mW RMS
    300 Ohm: 8.5mW RMS
Sensitivity:
    160mV input for 1V RMS output into 32 Ohm load (31mW)
    200mV input for 1.27V RMS output into 32 Ohm load (50mW)
Frequency response @ 1V RMS:
    flat from 45Hz to 20KHz, -1dB @ 35Hz, -2dB @ 24Hz
Total harmonic distortion into 16 Ohm load @ 1KHz:
    1V RMS (62mW) 0.015% 1.27V RMS (onset of clipping, 100mW) 0.04%
Total harmonic distortion into 16 Ohm load @ 10KHz:
    1V RMS (62mW) 0.05% 1.27V RMS (onset of clipping, 100mW) 0.1%
Unconditionally stable on capacitive loads

Source : http://www.ecircuitslab.com/2012/04/battery-powered-headphone-amplifier.html