Slow rise time on switch

[Guitar760]

I'm feeding the clock input of a D-Type Positive edge triggered flip flop with a momentary switch on a 5v rail, using 100k ohm for debounce. For the most part, the flip flop won't change states - every now and then it will actually switch but for the most part, nothing.

I hooked it up to my DSO and measured my rise time to be 700 microseconds, so I'm thinkinging it's just too slow for the flip flip to register as a clock input.

Is there a way to speed up the rise time, maybe with a transistor fed from the switch? I'm very limited on space, working a 15mmx18mm board

[T3sl4co1l]

Add a Schmidt trigger (e.g. 74HC1G14) in front.

What do you mean "100k debounce"?  A resistor alone does not provide this function.  Typically a switch or pushbutton is debounced by placing a large capacitor in parallel with the switch (0.1uF is typical), and using a large pull-down resistor (like 100k) so the voltage takes a long time (~10ms) to return to zero after the last contact bounce occurred.

Tim

[merlinb]

If you can replace the IC then you could substitute a D-type variant with built-in Schmitt triggers, such as:
http://www.farnell.com/datasheets/1724714.pdf