If your inputs is the scan signal then you can use uln2003 or uln2803, 2003 is less one channel than 2803, cd4511 is right.The 74HC/HCT4511 work in 5V and i will be using above it with uln2803.
The ULn2803 will convert the input 5V to GND
http://thetechnicalbrain.com/electronics/images_stepper/uln2803.jpg
If the CD4511 is not using scan signal to drive then you don't need the uln2003/ul2803, only you want to using scan signal and used the common cathode led then you will need the uln2003/2803 to drive the leds, the uln2003/2803 is a Darlington drivers, so you can treat them as a inverter has big current, when the input is high(1) then the output will be low(0).The 4511 takes 0000 and give 1111110 //0
and the ULN2003/8 will convert 1(high input) to 0(low output) and 0(low input will be give what) will convert x??
I am using decoder individual no scanning just driving!If the CD4511 is not using scan signal to drive then you don't need the uln2003/ul2803,
a 7.5k ohm resistor will give you 1.6mA to drive your 7 segment device.First, the base transistor between the 4511 outputs and the ULN2003 inputs depends on the current requirement of your 7 segment.
A quick calculation shows that with a 120 ohm resistor, the transistor is being driven with 100ma. Certainly that is too large. (Current=12V / 120 ohm = 0.1A or 100mA)
Using the rule of thumb of one tenth the load current, a 7.5k ohm resistor will give you 16mA to drive your 7 segment device.
The common pin was used for the inductive components as relay or motor to protect the bjt from back emf, so you can ignore it here.OK, I have connected the CD4511 with ULN2003.
The pin 8 E to GND and pin 9 COM to Vcc 12V.
and CD4511 120Ohm in between of ULn2003 is this correct, or should the output segment pin drive the ULN2003 with series resistance!
The 7.5k ohm resistor is a base resistor feeding a transistor in the ULN2003 array. The transistor then switches ~ 16ma to the LED. I'm on my phone; this thread is screaming for a schematic!a 7.5k ohm resistor will give you 1.6mA to drive your 7 segment device.
Normally, I used 4511 and the 7-seg led with common cathode, and connected the common cathode to ground.Hello,
I have just connected the C4511 with 12V, an the common cathode led segments.
4511 is working normally the oval led segment also bright in few mA.
I have kept the circuit on power for whole night chip was not fry .
so, should i use directly 4511 with common cathode ?
as ul2003 is not function at 12V.
by Jeff Child
by Jake Hertz
by Jake Hertz
by Jake Hertz