Can someone explain the schematic of this circuit and the IC?

Question

Heres the link http://www.escol.com.my/kits/ES-030.html please explain in detail about the pins of the IC in a simple manner

Answer 1

Get a copy of the data sheet online, it describes the function. This is a 5 bit divide by 10 counter with decoded outputs. The two transistors and associated parts form a clock generator to drive the counter.

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Answer 2

Q1 and Q2 and their associated passives generate a pulse stream. This goes into the clock input of the IC. Each time the clock pulses, the IC changes state.

The IC is a decade counter. This means a pulse stream on the clock input pin makes it repeatedly count in binary from 0 to 9, then goes back to 0, continuing to count again to 9, etc. It's outputs are decoded; this means that instead of outputting a binary number, it puts exactly 1 output high. So, for 0, output number 0 (Q0) is high, all the other outputs (Q's) are low. When it is clocked, Q1 goes high, all other outputs low. When clocked again, Q2 goes high, all other outputs low. This continues... Note the Q's on the IC (outputs) are different from the Q1 and Q2 transistors on the schematic.

The LED's are arranged in two rows; when counting from 0 to 4, one row lights sequentially; from 5 to 9 the other row lights going the other way. By interleaving the LED's in a single row, half light going one way, every other one lights as the light goes back the other way.

Answer 3

The "simplest manner" to explain what each pin does is still a diagram.

Have a look at the timing diagram (page 4) of this data sheet:

http://www.datasheetcatalog.org/datashee...

But I wonder whether you actually get any decent brightness on those LEDs....? The high-level outputs of the CD4017 are rated at 0.8mA @ Vdd = 9V which must be limited by the resistor R5  ~ 12kΩ.  If R5 is significantly lower than that, the IC may end up in silicon heaven.....

0.8mA is quite a low current for "normal" LEDs. Usually, there should be (10) driver transistors bringing the LED current to something like 10mA (with a 1kΩ resistor).....