Super Ni Cd Battery Charger 12 18V Circuit Diagram

A clever charger circuit that safely can charge any Ni-Cd battery. Offers charge current sellection, polarization detection and protection and the ability to connect many batterys in siries. Ni-Cd bateries can be recharged more than 1000 times before become useless. the charging current shoud be the 1/10 of the (Ah) of the battery. The bateries need 14 hours to be fully charged.Swhitch S2 is the current selection as folows: 50mA, 200mA and 400mA. LED D10 is the indicator for proper batery connection and/or wrong polarity checking. LED D9 is the charging indicator. The transformer is a 220V/2x12V 0.5A. 

Super Ni-Cd Battery Charger 12-18V Circuit Diagram

 PARTS LIST

R1,R4,R5=10K 

R2,R3=100K 

R6,R8,R10=1K 

R7=820 

R9=100 

R11=15 

R12=3,9 

R13=1,8 

C1=1000uF/40v 

C2=470pf 

D1-D4,D6=1n4001-7 D7,D8=1n4148 

D9,D10=LED IC=741 

TR1=BC548 

TR2=BD137 

TR3=2N3055

Datasheet file1: Click here to download LM741.pdf datasheet.

Datasheet file2: Click here to download BC548.pdf datasheet.

Datasheet file3: Click here to download BD137.pdf datasheet.

Datasheet file4: Click here to download 2N3055.pdf datasheet.

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6 12 Volt audio amplifier

The above is an amplifier circuit using supply voltages from 6 volts DC to 12 Volt DC. Power output of the amplifier is quite low with only 1 Watt 8 ohm impedance. You can apply this to the audio signal amplifiers that require strengthening are not so large as in the pocket radio.

Part List :
R1 =  100K
R2 = 39R
R3 = 100R
C1 = 100nF
C2 = 100uF
C3 = 100uF
C4 = 100uF
C5 = 470uF
C6 = 100nF
C7 = 68pF
C8 = 1nF
C9 = 47uF
IC = SFC2790C

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12 V Bidirectional Motor Control Circuit

This simple circuit drives DC motors with a maximum current of 1 A and can be built with readily available components.The output voltage is adjustable between 0 and 14 V and the polarity can be changed so that not only motor speed but also rotation direction can be adjusted by turning a knob. 

The circuit is also ideal as a controller for a DC model railway or small low voltage hobby tool. Power for the circuit is supplied by a 18 V mains transformer rated at 1.5 A. Diodes D1to D4 rectify the supply and capacitor C1 provides smoothing to give a DC output voltage of around 24 V. A classic ‘H’ bridge configuration is made up with transistors T1/T3 and T2/T4. Transistors T5 and T6 together with resistors R7 and R8 provide the current sense and limiting mechanism. The maximum output current limit can be changed from 1 A by using different value resistors for R7 and R8: IOUT = 0.6 V / R where R gives the value for R7 and R8. For increased current limit the mains transformer and diodes will need to be changed to cope with the extra current as well as the four transistors used in the bridge configuration. 

Circuit diagram:

  12 V Bidirectional Motor Control Circuit Diagram

 

Motor speed control and direction is controlled by a twin-ganged linear pot (P1). The two tracks of P1 together with R1/R2 and R3/R4 form two adjustable potential divider networks. Wiring to the track ends are reversed so that as the pot is turned the output voltage of one potential divider increases while the other decreases and vice versa. 

In the midway position both dividers are at the same voltage so there is no potential difference and the motor is stationary. As the pot is rotated the potential difference across the motor increases and it runs faster. The voltage drop across D5 and D6 is equal to the forward voltage drop VBE of the bridge transistors and ensures that the motor does not oscillate in the off position with the pot at its mid point.

http://www.ecircuitslab.com/2011/07/12-v-bidirectional-motor-control.html

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