Hi:

I have breadboarded a 0 to 9 counter using the CD4033. It doesn't work. I have confirmed
that the connections are as shown in the attached schematic. Can someone please tell me
if this is correct as I have seen several conflicting schematics.

Also, I saw somewhere that the CD4033 cannot drive even small 7-segment displays. Is that
true? If so, What would a driver circuit look like? The datasheet is rather confusing to a newbie.
The displays are common cathode 7.6mm in size but I have no further specs on them.

Thanks,
M

 

Is this schoolwork?

Post a schematic for those of us who don't care to use LTspice.

Also, I saw somewhere that the CD4033 cannot drive even small 7-segment displays. Is that
true? If so, What would a driver circuit look like?

From RCA datasheet:

 

Also, I saw somewhere that the CD4033 cannot drive even small 7-segment displays. Is that
true?

A long time ago it was almost true. 4000 series CMOS has a fairly limited output current, and when 7-segment displays needed 20mA they could get perhaps 5mA, so they would be rather dim.
Now 5mA is plenty of current for a 7-segment display as LEDs have improved, and 1mA should do for the high-brightness types.

If nothing is lighting up, make sure you have a common cathode display and that the cathode is connected to the negative supply.

 

Is this schoolwork?

Post a schematic for those of us who don't care to use LTspice.


From RCA datasheet:
View attachment 314332

Hi Dennis:

I am many decades past "homework"!

Thanks,
E

A long time ago it was almost true. 4000 series CMOS has a fairly limited output current, and when 7-segment displays needed 20mA they could get perhaps 5mA, so they would be rather dim.
Now 5mA is plenty of current for a 7-segment display as LEDs have improved, and 1mA should do for the high-brightness types.

If nothing is lighting up, make sure you have a common cathode display and that the cathode is connected to the negative supply.

Hi Ian:

Definitely common cathode. I thought that perhaps I misunderstood the data sheet wiring instructions.

M.

 

Hi Dennis:

I am many decades past "homework"!

Thanks,
E

Hi Ian:

Definitely common cathode. I thought that perhaps I misunderstood the data sheet wiring instructions with
regard to lamp test, reset etc.
Thanks.
M.

 

Hi maker,
Where did you get your CD4033 LTSpice model.

E

 

If you want further replies on your circuit design, you need to post your schematic in a common readable format.

 

I am many decades past "homework"!

Me too... Post your schematic.

 

Hi maker,
Where did you get your CD4033 LTSpice model.

E

Hi E:
I got it from Bordodynov. I am not simulating the circuit. I just used the Spice
model to illustrate how I connected the device. I actually have no schematic as
I just wired it up based on various multi-digit counter circuits that I found on
the internet. I am going to draw a schematic and post it shortly.
M

 

Me too... Post your schematic.

Schematic

 

Schematic

As you mentioned earlier, the counter can't drive displays directly. For a common cathode display, you'll the emitter follower driver shown in the datasheet. The datasheet references an integrated transistor array, but you can use any general purpose NPN transistor.

To verify whether or not the counter is working, disconnect the display and measure the voltage on the segment outputs.

Schematics are easier to read if the symbols have inputs primarily on the left and outputs on the right to facilitate the preferred left-to-right flow, and pin function is shown:

 

View attachment 314358
View attachment 314360
As you mentioned earlier, the counter can't drive displays directly. For a common cathode display, you'll the emitter follower driver shown in the datasheet. The datasheet references an integrated transistor array, but you can use any general purpose NPN transistor.

To verify whether or not the counter is working, disconnect the display and measure the voltage on the segment outputs.

Schematics are easier to read if the symbols have inputs primarily on the left and outputs on the right to facilitate the preferred left-to-right flow, and pin function is shown:
View attachment 314361

That's a good idea to have inputs on the left and outputs on the right. Thanks.
This also means that every schematic on the internet is incorrect.
Do I need to put a driver transistor on each segment meaning 7 drivers per digit
or does the driver on connect to the 2 cathode pins?

M

 

This also means that every schematic on the internet is incorrect.

I wouldn't say every schematic is in that style. The ones that don't conform were drawn by people who didn't know what they were doing. If you see more using pin order style, ignore them. They were likely drawn by novices.

Do I need to put a driver transistor on each segment meaning 7 drivers per digit
or does the driver on connect to the 2 cathode pins?

7 drivers per digit.

There are parts that can drive displays directly, but it'll take 2 chips.

 

I wouldn't say every schematic is in that style. The ones that don't conform were drawn by people who didn't know what they were doing. If you see more using pin order style, ignore them. They were likely drawn by novices.
7 drivers per digit.

There are parts that can drive displays directly, but it'll take 2 chips.

Oh man. Well that isn't going to happen. I have some CD4510s and CD4511s is a driver
necessary for those? If I would have to use two chips per digit anyway.

 

hi maker,
The earlier CD4033 source/sink currents are for the Old 'A' version.

The version 'B' which was released many years ago has much higher output currents, and should drive a modern
LED.
E

 

hi maker,
The earlier CD4033 source/sink currents are for the Old 'A' version.

The version 'B' which was released many years ago has much higher output currents, and should drive a modern
LED.
E
View attachment 314364

Hi E:

My devices are CD4033BE.

M

 

Hi E:

My devices are CD4033BE.

M

I have the counter working now but the digits are so dim that they are
hard to read. I guess that I need drivers. Perhaps LCD displays would work better.

 

Hi maker,
Are you using at 5V or 15v.?
The CD4033 is not suitable for LCD.
E

 

I have the counter working now but the digits are so dim that they are
hard to read. I guess that I need drivers. Perhaps LCD displays would work better.

You could try finding UDN2981 or UDN2982's. Mouser still had some the last time I looked, although they're not cheap!

 

Hi maker,
Are you using at 5V or 15v.?
The CD4033 is not suitable for LCD.
E

I am using 5 volts.