i'm making the LED dice with schematic on internet but i don't know this

Thread Starter

indusk9912

Joined May 15, 2022
10
1653197609998.png
Hi, I'm making dice with schematic that i found on internet.
I know how 555timer and CD4017 works.. but i don't know why 1N4148 is connected between resister and CD4017's output terminals.
 

Ya’akov

Joined Jan 27, 2019
5,659
Welcome to AAC.

If the diodes weren't present it would be possible for one pin going high to send that power to the other, commoned pins on the 4017. Follow the current flow in the circuit for any pin.
 

bertus

Joined Apr 5, 2008
21,896
Hello,

Also the diodes make a matrix to determine wich leds are to go on.
Led 7 ( the middle one ) will be much brighter as there is only one led in the line.
The others all have two leds in the line.

Bertus
 

demonstraten

Joined May 24, 2022
1
In this case, you need to very carefully monitor the flow of current in this circuit. Especially if LED lamps are connected in it. However, an unpleasant surprise may be waiting for you here: the declared power may not correspond to the actual one, and the lamp will shine weaker than expected. In addition, the brightness of the LEDs decreases over time. It is possible that the bulb will have to be changed long before the expiration of its service life due to the fact that it began to shine too weakly. (Links was deleted)
 

Thread Starter

indusk9912

Joined May 15, 2022
10
i have another question... i modified the circuit(1st picture below) and see it works well in Multisim.
So implemented it on the breadboard but it doesn't work as i simulate. 1653485430280.png
i search another circuit on the internet and change/add some elements. (marked green below)
1653485846131.png
it works well but i don't know why. how they work?
 

dl324

Joined Mar 30, 2015
14,458
it works well but i don't know why. how they work?
It would seem that the output of the timer isn't able to clock the counter (mixing and matching TTL and CMOS isn't for beginners). The 10k pullup resistor fixes that problem. The 0.1uF capacitor shouldn't be required.
 

Thread Starter

indusk9912

Joined May 15, 2022
10
It would seem that the output of the timer isn't able to clock the counter (mixing and matching TTL and CMOS isn't for beginners). The 10k pullup resistor fixes that problem. The 0.1uF capacitor shouldn't be required.
But if I remove it, it shows an error message in multisim
 

Thread Starter

indusk9912

Joined May 15, 2022
10
As a test, remove the buzzer and C2.
i removed it both, but error still occured. i did it on the breadboard too, but LED lights up sequentially whether switch is on or not. (4017 keeps counting when switch is off) I think capacitor seems to be needed.
 

Thread Starter

indusk9912

Joined May 15, 2022
10
Is the pullup resistor still installed?

The capacitor isn't needed.
Sorry for the late comment. i installed the pull-up resistor but still error occurs on multisim.
so i build the circuit on the breadboard, it worked. but i want to install the buzzer so it can make sounds when it's working. what should i do?
 
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