Part Number: CD4027B
I attached my schematic with CD4027B. I have connected toggle button on P2 and when press the button the 14V comes to K1, J1 and through R10 10Ohm C8 100n to CLK1 but the Q1 is always 12V and Q1_n always 0V
please can you help?
What is the purpose of the circuit? What do you expect to happen?
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In reply to Clemens Ladisch:
When I press the button I want to toggle the output Q on the rising edge of the CLK.
Upon press the J and K are 1 and the CLK is rising.
is it possible that the RC circuit are the problem?
In reply to ZeroD:
Just connect J and K directly to VDD; their state is relevant only during a rising edge.
i connected the J and K direct to VDD=12V, and now when i press the button the Q output changes but when i release the button then it changes back to previous state?
J=1, K=1 -> button press CLK from 0->1 -> Q from 1->0, release the button Q from 0->1
i also removed C7 and C8 but i get the same thing.
( one observation when i unplug the board, the capacitors have some charge left, and then when i press the button the Q changes and stays in the state to another button press ??)
I'd guess that the RC filter is too weak, and the button is still bouncing. Check with an oscilloscope.
Could you provide some scope shots of the operation with the issue you are experiencing. Also make sure to zoom in on the button press to verify if the button is still bouncing. The RC may be too small.
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In reply to Dylan Hubbard:
for some season after the CLK input goes from high to low the Q,Q_N changes again
a) regarding button press denouncing RC
I have first RC then the buffer CD4050BE and then the button press signal goes to CD4027BE JK bistabil CLK input.
I don't see any bouncing of the button:
Blue button signal
Yellow after the RC
Green on the CD4050BE = CLK in of the CD4027BE
b) when i release the button the clk goes from high to low and then the output changes ??
Could you zoom in on the falling edge green signal. As much as you can while keeping the whole edge on screen. I think I might know whats going on here.
i will do that but currently i don't have the oscilloscope by hand. i will do it ASAP
please can you explain what do you think that is going on?
here are the oscilloscope shots:
blue: after RC button -> buffer input
purple: buffer output -> J-K CLK input
green: j-k output Q and QN
zoomed rising edge
zoomed falling edge
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