Automatic 9-Volt Ni-Cad Battery Charger

Circuit Diagram

Good care of nickel-cadmium batteries for long life. However, they must be handled and loaded with special care. It is therefore important to start downloading Ni-Cad to 1 volt per cell, make sure the battery is empty, and then start charging. Manufacturers recommend a charging current of the capacity of 1:10 for a period of approximately 15 hours without interruption. In fact, learning hard lessons when we switch to the charger for 15 hours and one or more cells within the battery, see forgotten, no longer accept a charge. This is the reason that the circuit is fully automated above.

All you have to do is connect the battery and press "Start". When the flush cycle is completed the latch circuit load for 15 hours. After 15 hours, keep the circuitry of a battery trickle charge "top-up". Before schematic details, I would explain part of the description of the components in the diagram. The descriptions are basis on European grades 120E, 150E, etc. The 'E' is so ohms 120 ohms, 150 ohms. The main circuit HEF specifies the type CMOS integrated circuit which is not easily most of Canada. So easy to make any type of few CMOS chip like the MC4020, MC4011, MC4047, and Motorola. The BC548B irreplaceable with a NTE123AP (PLEASE NOTE: make sure it is the type of "AP" is a completely different NTE123A normal transistor) and works with ECG123AP 2N3904 also. Use correct pin locations from the ECB to the European type can be reversed with ECG956. The type of IC LM317T is TO-220-type and interchangeable or NTE956 with the LM339N by a NTE834 or ECG834 version.

Although this charging circuit looks very impressive and can be a bit tricky, as it certainly is not hard to catch on. The circuit connected to provide DC power source 16.5 to 17.5 volts voltage maximum when the CMOS integrated circuit is defective. Because they want to develop a separate power supply to drive this circuit. I mean dynamic supply is fully adjustable. First connect a (to-be dependent) 9 volt nickel cadmium batteries for proper connections. Then connect it to the mains. During connection of the capacitor 1nFstarts both RS flip-flop of IC1D, IC1C, IC1B, IC1A formed and pulls the pins 3 and 10 "high" and pin 11 and 4 "low". The pulses are given by the free running adjustable multivibrator IC4. Frequency IC4 10uF capacitor, resistor potentiometer 220K and 100K determined. The clock is ticking, but continually behind the counter IC5 mention yet because it is pin 11 (this pin is called master reset) remains high.

If the "START" button is squeezed, the pin 4 high IC1Aand examined TR4, made visible with the red color LED (D9) which remains fixed. NC now discharges through the transistor and resistors 100 ohms. The potentiometer 10 K (right in the figure) is set so that when the actual battery voltage is under recesses 7 volts, the output voltage of the IC3 become low and output Pin 11 is HIGH of IC1A. At this moment also the output pin 10 goes LOW of IC1D, and the red color LED is off. Since 11-pin output raised green color LED (D8) lights at the same time increases the voltage to the battery needs recharging. The load current is decided by the 120 ohms, 150 ohms, 1K potentiometer on the right side of the IC2. In fact, one could use a resistor, but the actual output voltage can distinguish between various brands for the IC2 to about 1.25 volts. Because the load current is divided by the value of resistors, potentiometers can flow to the exact value of one 9 volt nickel-cadmium be adjusted. (In my experiment the type of the battery is 300 mA, so that the charging current is 30 mA (C/0.1) must be adjusted. Simultaneously, the lower the output pin 10 of counter IC1D start the clock. Pin 9 IC5 arrive pulses red color LED lights. This is performance for two reasons; the clock can be adjusted by potentiometer 100K, the correct value and then the red color LED and for the same period last OFF for 6.59 seconds , except for the fact that the green LED shows the charging current can verify that all the time is accurate. When the pulse count (8192 x 6.59 = 53985.28 sec x 60 x60 = 14.99 hours), output pin 3 goes IC5 reached again, turns the transistor TR1 and continues the two counter start position. Charging stops and looks at the trickle charge resistor and diode D2 10K and maintains the battery charge.

The project adjustments are very simple and it nothing to worry about this. Turn potentiometer 10K walker in the direction of resistance, 12K field terminal 10K resistor or the diode D2, like as the adjustment pin of the IC2, a voltage of 7 volts at the terminals of the battery, turn the camera off and now slowly turn the pot backward til the green color LED light comes on. Turn off the device and remove the connections made to fit. Place an ammeter between the output terminal and the battery and insert the new drive. Battery if it is completely empty completely unloaded (at a safe level) and from the edge of 7 volts is reached for the charging cycle. The charging current is set through 1K Potentiometer (connected in series with the resistor in parallel with 150 ohm resistor 120) precisely to the longing value. Addendum: It is highly recommended to keep small 100nF ceramic capacitors in the power supply lines for each IC power CMOS are possible disturbance trivial.