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Electronics Circuit Application

Cell Phone Travel Charger Circuit Diagram >>

Charge Your Mobile Phone While Enjoying

Here is an ideal Mobile charger using 1.5 volt pen cells to charge mobile phone while traveling. It can replenish cell phone battery three or four times in places where AC power is not available. Most of the Mobile phone batteries are rated at 3.6 V/500 mA. A single pen torch cell can provide 1.5 volts and 1.5 Amps current. So if four pen cells are connected serially, it will form a battery pack with 6 volt and 1.5 Amps current. When power is applied to the circuit through S1, transistor Q1 conducts and Green LED lights.

When Q1 conducts Q2 also conducts since its base becomes negative. Charging current flows from the collector of Q1. To reduce the charging voltage to 4.7 volts, Zener diode D2 is used. The output gives 20 mA current for slow charging. If more current is required for fast charging, reduce the value of R4 to 47 ohms so that 80 mA current will be available. Output points are used to connect the charger with the mobile phone. Use suitable pins for this and connect with correct polarity..... Electronics Circuit Application

R1 = 1K
R2 = 470R
R3 = 4.7K
R4 = 270R
R5 = 27R
C1 = 100uF-25V
D1 = Green LED
D2 = 4.7V/1W Zener
B1 = 1.5Vx4 Cells
S1 = On/Off Switch
Q1 = BC548
Q2 = SK100

Electronics Circuit Application

Alkaline battery new charging circuit >>

Here is a low current charger I designed in an attempt to extend the life / recharge regular non rechargeable alkaline batteries. The trick to doing this is three things.

• Use a low current over a longer period
• Charge before they become too drained
• Charge to no more than 110% of the cells capacity (eg 1.5v charge to 1.65v and stop)

The nice thing about using alkaline batteries is that they have no internal discharge unlike Ni-Cd and Ni-Mh rechargeable’s, and are therefore suited to low current drain applications such as remote controls, clocks or things you don’t use often such as torches.In my tests I have found the lower charge rate, the better the charge and the less chance of a cell leaking electrolyte. Also, if a cell becomes too flat or completely flat, it will not take a good charge and will also probably leak electrolyte and possibly even pop open. The idea here is to keep them topped up. Lets say you have fresh batteries in a torch and you used it for a while. The cells have drained to around 1.3v for example. Put them on gentle charge with this circuit, monitor the voltage and stop when it reaches 110%. That would be 1.65v for one cell or 3.3v for two cells in series. Do not charge beyond 110% or there is a risk of cell leaking or even popping open / exploding. Its also advisable not to try to charge an alkaline battery that is completely flat. They don’t absorb a charge and just leak in my experience. Some of my tests I done outside in the winter (around 2°c) and I found the cells hit 1.65v quite fast but didn’t absorb much of it due to high internal resistance at cold temperatures. Charging should be carried out at room temperature, around 20°c.

Here is a constant current supply circuit schematic diagram using the LM317 variable voltage regulator. It is a very simple circuit for charging alkaline batteries. It will provide a stable constant current which is adjustable by switching different values of resistors. The input voltage must be at least 6v higher than the battery(s) you wish to charge. The LED, BC548 and 470Ω resistor provide an indication of current flow to show that your battery connections are good. They can be omitted if you wish to make the circuit simpler. I used a 12 way rotary switch set to 5 way to select different resistors to give output currents of around 5, 10, 20, 30 and 40mA. The idea being for 9v PP3 types I would use 5mA. For AAA’s 10mA. AA’s 20mA, C’s 30mA and D’s 40mA. This is just my guideline, you can try what you like! Just remember more current is not good for charging alkaline non-rechargeable batteries.
Electronics Circuit Application

low power Fluorescent Lamps >>

Electronics Circuit Application

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build Midnight Security Light Circuit >>

Description

Most thefts happen after midnight hours when people enter the second phase of sleep called ‘paradoxical’ sleep. Here is an energy-saving circuit that causes the thieves to abort the theft attempt by lighting up the possible sites of intrusion (such as kitchen or backyard of your house) at around 1:00 am. It automatically resets in the morning. The circuit is fully automatic and uses a CMOS IC CD 4060 to get the desired time delay. Light-dependent resistor LDR1 controls reset pin 12 of IC1 for its automatic action. During day time, the low resistance of LDR1 makes pin 12 of IC1 ‘high,’ so it doesn’t oscillate.

After sunset, the high resistance of LDR1 makes pin 12 of IC1 ‘low’ and it starts oscillating, which is indicated by the fashing of LED2 connected to pin 7 of IC1. The values of oscillator components (resistors R1 and R2 and capacitor C4) are chosen such that output pin 3 of IC1 goes ‘high’ after seven hours, i.e., around 1 am. This high output drives triac 1 (BT136) through D5 and R3. Bulb L1 connected between the phase line and M2 terminal of triac 1 turns on when the gate of triac 1 gets the trigger voltage from pin 3 of IC1. It remains ‘on’ until pin 12 of IC1 becomes high again in the morning. Capacitors C1 and C3 act as power reserves, so IC1 keeps oscillating even if there is power interruption for a few seconds. Capacitor C2 keeps trigger pin 12 of IC1 high during day time, so slight changes in light intensity don’t affect the circuit.

Using preset P1 you can adjust the sensitivity of LDR1. Power supply to the circuit is derived from a step-down transformer T1 (230V AC primary to 0-9V, 300mA secondary), rectifed by a full-wave rectifer comprising diodes D1 through D4 and fltered by capacitor C1. Assemble the circuit on a general-purpose PCB with adequate spacing between the components. Sleeve the exposed leads of the components. Using switch S1 you can turn on the lamp manually. Enclose the unit in a plastic case and mount at a location that allows adequate daylight.

         parts list

• P1 = 100K
• R1 = 120K
• R2 = 1M
• R3 = 100R
• R4 = 100R
• C1 = 1000uF-25V
• C2 = 100uF-25v
• C3 = 100nF-63V
• C4 = 1uF-25V
• D1 = 1N4001
• D2 = 1N4001
• D3 = 1N4001
• D4 = 1N4001
• D5 = Red LED
• D6 = Green LED
• IC = CD4060
• TR = BT136
• T1 = 9v 300mA Transformer
• L1 = 230V-60W Bulb
• SW = On/Off Switch 

Caution

Since the circuit uses 230V AC, many of its points are at AC mains voltage. It could give you lethal shock if you are not careful. So if you don’t know much about working with line voltages, do not attempt to construct this circuit. We will not be responsible for any kind of resulting loss or damage.

Removing Nokia 6555b Logic Board >>

 

Electronics Circuit Application

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