CD4013B: Interfacing CD4010B with CD4013B

Hi Kristofer,

Have you tried the connection with no resistor between the output and CLK input? It would be helpful to have a picture of setup but since you mentioned it's on a breadboard I would suspect breadboard parasitics are the primary cause here.

Best,

Malcolm

This is what the clock looks like with no resistor:

This is the D-FF side with an 80k resistor in series:

This is the buffer side of the 80k resistor in series:

Since this is a breadboard, are you able to connect the clock signal directly to the DFF skipping the buffer? This does look like breadboard parasitics are responsible here. The rise time of the buffer output does not look that bad. The glitching and poor performance after the resistor can probably be explained by breadboard quality and whatever physical connections you are using. Can I get a picture of the actual breadboard?

Best,

Malcolm

Connecting the input directly to the clock does not solve the issue. This may be because of the excessive rise time of the signal, which is why it needed the buffer. Looking at the D-FF output, it is flipping multiple times with each single input during both the rising and falling edges of the clock.

Unfortunately a photograph will not be possible.

Kristofer,

What does the connection from the buffer to the DFF look like? What do connections in general look like? Just jumper wires across the board?

Best,

Malcolm

Yes, standard jumper wires are used for all connections.

Mechanical switches bounce. This is why figure 9 shows a low-pass filter and a Schmitt-trigger buffer.

The R-C filter must be slow enough to filter out any bounces. The only CD4000 buffer with Schmitt-trigger inputs is the CD40106B, an inverter.

I am not using a mechanical switch. This is a user input with a very slow rise time. I am aware of switch bounce. I don't think debouncing will fix this, but I can try the CD40106B.

Kristofer,

How are you power supplies configured and connected? I suspect there are likely some issues with the power supply here. I would not expect the CD4010 buffer to have this slow of a rise time, to be honest. The dip on the input into the CD4013 suggests some sort of power supply leakage to me.

Best,

Malcolm

I am running off of a 9V battery. I have experimented with several bypass capacitors, and they seem to help. Placing 3.2uF as well as .1uF on the D-FF supply shortens the width of the double pulse from 2us to 200ns. However, it is still there and this should be plenty of capacitance to smooth out the power supply.