Yet another example of the kind of crap you find on YouTube. CD4026 can't source or sink enough current to drive 7 segment displays directly.

Just looked at the datasheet. You are right. It can sink a few mA (less than 10) and it can source a few mA (less than 10). Since we normally want something like 10-15 mA for each led, the CD4026 does not seem to be a good choice for 7 segment display.

 

Just looked at the datasheet. You are right. It can sink a few mA (less than 10) and it can source a few mA (less than 10). Since we normally want something like 10-15 mA for each led, the CD4026 does not seem to be a good choice for 7 segment display.

IIRC, the outputs are "standard"; only guaranteed to source half a mA @ Vdd=5V, around 1mA typical. To get anywhere near 10mA, Vdd has to be 15V.

 

You have right.
I seen the datasheet and it suggest use of ca3082, but i asked because on web i find a lot circuits without these driver, where the display are supply directly the ic4026.

 

i asked because on web i find a lot circuits without these driver, where the display are supply directly the ic4026.

You can't believe everything you see on the Internet.

 

You have right.
I seen the datasheet and it suggest use of ca3082, but i asked because on web i find a lot circuits without these driver, where the display are supply directly the ic4026.

The simple answer is that a few mA might be enough for small led in 7 segment. Those numbers, 10-15 mA, that I mentioned earlier are usually used for larger 3-5 mm led.

The weird part for me is that 4026 can neither source nor sink enough current. Sourcing current is hard for chips so I am not surprised by that. However, sinking is usually works really well.

Bottom line. kyu, you can build your circuit and see if 7 segment is bright enough and legible enough for your needs. If not, then you 4026 datasheet and its recommendations on how to connect 4026 to 7 segment using additional chips.

 

Ok,
i will made the circuit so i can see how it work

 

MC14553 was designed to drive 3x common anode 7 segment LEDs. But if you want to use CC LEDs, then the digit drive has to be inverted with 40106 to a NPN transistor. Instead of using 4543B, use 4511 for CC.


The digit drive stage was simplified and current limiting resistors on the segments were also removed. The clock signal is generated by 1nF capacitor connected on CIA and CIB.

Data sheet is also attached. See Page 7 for the sample schematic driving 6 digit LED.

Allen

 

Thank you for this schematic.
Unfortunately
I have more than one (two digits) display as that on first post.
I have also more than one (one digit) display.
While i haven't the MC14533 ic.

 

Thank you for this schematic.
Unfortunately
I have more than one (two digits) display as that on first post.
I have also more than one (one digit) display.
While i haven't the MC14533 ic.

You need latches (included in some decoder drivers). Its more common to find latches at the BCD part of the circuit because it only uses 4 and not 7 or 8. If you go for 8 bit latches (then you can also control the DP). Its usual to use the OE control with an inverter between the 2 OE pins so one latch is enabled, and the other tri-stated at any given time. The strobe pin for the digits are controlled by the same pulse train as the OE pins.