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The Super Universal Battery Charger Circuit Diagram output voltage is adjustable and regulated, and has an adjustable constant-current charging circuit that makes it easy to use with most NiCad batteries. The charger can charge a single cell or a number of series-conoected cells up to a maximum of 18 V. 

Power transistors Ql and Q2 are conoected as series regulators to control the battery charger`s output voltage and charge-current rate. An LM317 adjustable voltage regulator supplies the drive signal to the bases of power transistors Ql and Q2. Potentiometer R9 sets the output-voltage level. A current-sampling resistor, R8 (a 0.1-!J, 5-W unit), is conoected between the negative output lead and circuit ground. For each amp of charging that flows through R8, a 100 mV output is developed across it. 

The voltage developed across RS is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor RIO. As the charging voltage across the battery begins to drop, the current through RS decreases. Then the voltage feeding pin 5 of U3 decreases, and the comparator output follows, turning Q3 back off, which completes the signal`s circular path to regulate the battery`s charging current. The charging current can be set by adjusting RlO for the desired current. The circuit`s output voltage is set by R9. 

 

Charging of the cell phone battery is a big problem while touring as energy provide supply is now not on a standard basis on hand. In case you keep your mobile phone switched on repeatedly, its battery will go flat within to 6 hours, making the mobile phone useless. A absolutely charged battery grow to bes necessary when your distance from the closest relay station increases. Here is an easy costr that replenishes the mobile phone battery inside to hours. Fundamentally, the costr is a current-limited voltage supply. Usually, mobile phone battery packs want three.6-6V DC & one hundred eighty-200mA present for charging. These frequently include NiCd cells, every having one.2V ranking. Current of 100mA is for charging the cell phone battery at a gradual fee. A 12V battery incorporateing eight pen cells provides adequate present (one.8A) to cost the battery related across the output terminals.

Diagram  of cellphone costr

The circuit additionally monitors the voltage stage of the battery. It robotically lowers off the charging device when its output terminal voltage will increase above the predetermined voltage level. Timer IC NE555 is used to charge & monitor the voltage stage within the battery. Control voltage pin five of IC1 is supplied with a reference voltage of five.6V with the help of zen-er diode ZD1. Threshold pin 6 is provided with a voltage set via VR1 & trigger pin two is equipped with a voltage set by using VR2. When the discharged mobile phone battery is connected to the circuit, the voltage given to trigger pin two of IC1 is beneath 1/3Vcc & therefore the flip-flop within the IC is switched on to take output pin three excessive.

When the battery is fully charged, the output terminal voltage will increase the voltage at pin two of IC1 above the trigger level threshold. This switches off the flip-flop & the output goes low to terminate the charging means. Threshold pin 6 of IC1 is referenced at 2/3Vcc set with the help of VR1. Transistor T1 is used to reinforce the charging current. Value of R3 is very important in offering the vital present for charging. With the given price of 39-ohm the charging present is round one hundred eighty mA.

The circuit can be built on a tiny general-purpose PCB. For calibration of cut-off voltage stage, use a variable DC energy source. Connect the output terminals of the circuit to the variable energy supply set at 7V. Fine-tune VR1 within the center place & gradually fine-tune VR2 unless LED1 goes off, indicating low output. LED1 should activate when the voltage of the variable energy supply scale backs under 5V. Enclose the circuit in a tiny plastic case & use suitable connector for connecting to the cellphone battery.