PC-controlled semiconductor tester (2):

The circuit diagram of the power supply shows that the semiconductor tester has an on-board step-up voltage converter that is powered from the 12-V supply in the PC. The 5-V supply of the PC is also used to power certain parts of the circuit. The 12-V supply of the PC is connected to a step-up converter via a 4-way connector as used for floppy disks and hard disks. The current requirement of the 12-V input is about 2.2 A. If this current is not available in your PC, it is still possible to use the semiconductor tester with a correspondingly reduced maximum collector current for the device under test. The input current of the voltage doubler in the power supply is about 2.2 times the output current. Hence the 2.2 A input current requirement if a maximum collector current of 1 A is to be achieved. The quiescent current drawn by the power supply is about 150 mA.