Connect to make a mod 6 counter Connect all unused inputs to

Connect to make a mod 6 counter. Connect all unused inputs to V_CC or GND as appropriate. Connect to make a mod 100 counter. Connect all unused inputs to V_CC or GND as appropriate.

Solution

Insert the 7490 into the breadboard. The notch on the chip should be at the top and the chip should straddle the blank line that divides the rows. Pin 1 of the 7490 is the first pin to the left of the notch.

Locate the 7490 pins labeled \"VCC\" and \"GND.\" Refer to the 7490 datasheet for the pin description. Connect VCC to breadboard power and connect GND to breadboard ground. Use jumper wires for the connections.

Locate the 7490 pins labeled \"R9(1)\" and \"R9(2).\" Use jumpers to connect both pins to breadboard ground.

Locate the 7490 pin labeled \"CKA\" or \"Input A.\" Leave the CKA pin open for now. A frequency generator, clock pulse or another counter will be connected to this pin. An alternating (+5V to 0V) signal at the CKA pin causes the 7490 to sequence through the numbers. The speed of that signal determines how fast the numbers will be appear at the 7490 output pins.

Locate the four output pins of the 7490.They are labeled \"QD,\" \"QC,\" \"QB\" and \"QA.\" Connect a jumper to each output and leave the other end free.

Turn the breadboard counter-clockwise so that the 7490 is horizontal. Insert the free end of each output jumper into adjacent breadboard rows. Follow the left-to-right order of the outputs, which is: QD, QC, QB, QA. The jumper ends will form a horizontal line which will be parallel to the 7490. This is where to connect the indicators, such as LEDs.

Locate the 7490 pin labeled \"CKB\" or \"Input B.\" Connect QA to CKB with a jumper. This connection sets the counter to BCD-output mode.

Locate the 7490 pins labeled \"RO(1)\" and \"RO(2).\" Connect QB to RO(1) with a jumper and connect QC to RO(2) with a jumper. This sets the Modulus to six. In BCD, six takes the following form: QD=0 QC=1 QB=1 QA=0. The 7490 will reset to BCD 0000 when both RO(1) and RO(2) receive a \"1\" from QC and QB. The MOD-6 output sequence is as follows, from zero to five: 0000, 0001, 0010, 0011, 0100, 0101.