Wednesday 4 March 2015

Alarm light circuit for battery charger

This is Alarm light circuit for a general battery charger. It is simplified circuit and cheap, use one transistor BC557 and display with 2 LED.
Battery that use with car, motorcycle or Lamps lighting of fishermen. Always is Lead-acid batteries. Which each cell in the battery will have the voltage per cell is about 2.3 volts.duration of charging depends on current charging. By the currentmuch takes quick charger or less currents charge time is long. Between that charging the current will reduce continuously until the lowest is about 10mA. Which battery is near full charge. But we cannot know that battery full or not. because no signal alarm.
The circuit in Figure 1 is alarm light circuit for battery charger. By while charge battery will has the green light show all time. And will go out when full charged. Which the green LED because the transistors-Q1 works. Since while charge will has current provide Enough to circuit. And has resistors-R1, R2 to set bias to transistors. The Diode-D1 limits the voltage exceeds 0.7 volts.
Alarm-light-circuit-for-battery-charger
Figure 1 The alarm light circuit for battery charger
When battery is fully charged the green LED1 goes off. Because Currents stops flowing or may flow less than 10 milliamperes. But LED1 green may be extinguished, because the wrong battery polarity, short circuit at an output. The LED2-red will glow when the wrong battery polarity.
This circuit can use with the charger that can provide charge current between 1-3 amperes. If provide current charger 1 Amperes then provide use D1-1N4001-Diode, or if is 3 amperes also use diode 1N5401 instead. The resistors-R3 of 470 ohms will be used with the Rechargeable battery of 6 volts, if change as 680 ohms resistors to use for the battery 12 volts
How to builds
This project is not used many components so can assemble on the universal PCB board as Figure 2
In the assembly circuit, Starting equipment lowest first such as Diode and then resistors and sort of high continuously.
For the device has various polarity should be careful in the assembly circuit. Before placing these components will must set the polarity at PCB and the part match together because If you put backward, may cause equipment or circuit damage. How to check polarity and input device.
components-layout-of-this-projects
Figure 2 the components layout of this projects
The soldering iron is less than 40 watts. And Use of lead solder containing lead and tin in the ratio of 60/40. Including the need also to have a flux inside the lead.
The after that put the components and completely solder. to check correctness again But if you enter the wrong position. Should use a desoldering pump or a Desoldering remover To prevent damage to the PCB.
The components List
Resistors size ¼ watts +5%
R1_________56 ohms
R2_________100 ohms
R3_________470 ohm (680 ohm)
Semiconductors
D1_________1N4001 (1N5401)
D2, D3_____1N4148___ 75V 150mA Diodes
LED1______5mm Green LED
LED2______5mm Red LED
Q1________BC557B__ 45V 100mA PNP Transistor
Others components.
The universal PCB board.

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