The Internet caught the eye diagram of the automatic charger Ni-Cd batteries developed by Yuri Bashkatov. Assembled the circuit on the breadboard — not working. Modeled it on the computer using the program Work Bench. The result is what is shown in the diagram. The device operates as follows. The transistor VT1 (p-n-p) is open if at its base there is a negative potential, which may appear when the VT2 transistor (NPN) open — this, in turn, occurs if the potential at its base is installed with the variable resistor R4 will be 0.3 — 0.4 V higher than on its emitter.
The emitter of the transistor VT2 is connected to the cathode of the thyristor VS1 and rechargeable battery. As soon as the voltage across it reaches a threshold, transistor VT2 is closed. Behind him is closed and the transistor VT1. The thyristor will turn off, the charge will stop. Thus overcharging the Ni-Cd battery.
Resistor R4 is the threshold of the automatic device. Informative the magnitude of the voltage on the base (boundary value of the charging voltage) it would be possible for the database to connect the voltmeter. However, the authors felt that the better connected a voltmeter to the emitter of the transistor VT2. Thus, immediately upon connecting the battery see what voltage. When the button is pressed, controlling the voltage on the voltmeter, set the voltage on the emitter with a resistor R7 then without releasing the button ЅА1, set the threshold device resistor R4, by controlling the activation of the ignition ballast bulbs ЕL1. Button release, the light should illuminate, the batteries began to recharge once the voltage on the battery reaches the threshold mode, the light goes out, the charge will end.
Circuit diagram of automatic battery chargers for Ni-Cd battery
Circuit Board automatic charger
Practice charge Ni-Cd batteries have shown that the ultimate tension recommended in the instructions, not 1.2 V, and not even 1.5 V, and 1.7 V, so for two batteries I set the threshold to 3.4 V.
And finally, knowing that Ni-Cd batteries have a “memory” before charging, they should be discharge current of 150mA, and to do this exercise (discharge/charge) is recommended 3 to 4 times.
A. PARTIN, L. MARTINA, Ekaterinburg
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