7 segment decoders

ScottWang

Joined Aug 23, 2012
7,397
24V → 12K(up)+10K(down) → CD4511 → (another pin 0f 10K to GND) common pin of voltage divider output 10.9V

> an if we are operating 4511 at 12V an 5v as input will this not work??

Yes, it won't work.
 

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Vin = 24V
R1 = 10K
R2 = 4.7K
Vo = 24V*(4.7K/(10K+4.7K)) = 8V.

Will 8V is enough??
C4511 is at 12V from Transformer external source not from PLC!

and Both PLC and led should be gnd for reference??
 

ScottWang

Joined Aug 23, 2012
7,397
Calculating the percentage of Vih and Vdd.
Vdd = 15V
Vih = 11V
P% = 11V/15V = 73%

The Vih of CD4511BE is 73% of Vdd, so the Vih = 12V* 73% = 8.76V.
It means that the mini input voltage of "high" level is 8.76V.

If you calculate the percentage of Vih and Vdd when the Vdd is 10V then the P% will be 70%, maybe you could adding them and divide them as 71.5%.
 

ScottWang

Joined Aug 23, 2012
7,397
The brilliance and brightness are quite strong.
Vout dc = 9Vac*1.414 =12.7V
How is the current limited resistor and how much current do you respect?
 

ScottWang

Joined Aug 23, 2012
7,397
Have you measure the I and Vf of led, and the 12Vdc real voltage?
Assuming that Vcc is 12V, 5 leds and the Vf of led is 2V, (12V-(2V*5))/120 ohm=2V/120 ohm = 16.667mA
Is that what you arrange the led display that you used 5 leds to be a segment?
 

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Hello,
The Vcc is 12.42 right now is adapter SMPS after that there will be transformer!
total current is 222mA for 0 in 4 digits!
the voltage across string is 9.96V, Vf of led is 1.92V, current per segment is 8.89mA and voltage across resistance is 1.8V.
 

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Here is the circuit only Vcc at 12V, and input with pull down of 10k and input of 9.4K same!
One thing more the input wire i have is cable of 5 wires. in circular color coded (I don't know the Name)
what will be the maximum length of input wire to work on it?
 

Attachments

SgtWookie

Joined Jul 17, 2007
22,230
You may want to do a Google search for "multiplexing 7-segment displays". This technique allows you to use 7 (or 8 if you are using the decimal points) data lines common to all of the digits, plus one select line for each digit.
 

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Hello,
There is some problem as THE PLC work in 24V and this circuit at 12V.
The Input are connected to Gnd with pull down of 10K, when the inputis connected to 12V it work as BCD 8421 on display.
But when i use external 24V the Gnd of both are common and the 24 to input the signal does not work well.
how to connect both of PLC 24 nad internal 12V led display together
 

ScottWang

Joined Aug 23, 2012
7,397
The below was what suggested in #41.

24V → 12K(up)+10K(down) → CD4511 → (another pin 0f 10K to GND) common pin of voltage divider output 10.9V

Your values of resistor has a little higher than the Vdd.
 

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
So, you mean to say 24V to 12K(up)+10K(down) ?
and is there any pull down or input requirement of another input resistance to CD4511 ??
 
Top