Need very time to see wave shape on oscilloscope

[Jasonbit]

Hello folks,

I have this Picasso  https://snag.gy/hme2xG.jpg

The purpose of capacitor it reduce or eliminate bouncing the switch end the user wide button. On my oscilloscope I can see the effects of the capacitor but I don't know well I should parameter the equipment. On this print screens, https://snag.gy/KIcTe6.jpg and https://snag.gy/5ApnSw.jpg you can see  the wave signal with capacitor 10uF and without capacitor. But to achieve this signal wave I need parameter time/div in 1 second per time. I need wait a second to can see have shape each time the button is pressed.

I am configuration the equipment well?

[JS]

What are you reading the switch with? Are you working with a low power device?

The values seems off, 10k and 10µF is slow, what you are seeing is a fast discharge (charge actually, the cap is discharged when going high and charged once the switch is released) till you are under the LED conduction voltage and then it keeps discharging with the 10k alone, that's why the shape isn't a simple time constant exponential discharge.

You can get away using a smaller cap, or a smaller resistor, but that resistor will chew more energy while the button is pressed, so if you are working with a low power device a smaller cap is better, but the LED could charge it too fast. You want the charge to be slow enough so the bouncing is faster than the discharge of the cap. I've got away with 4.7nF last week but it only connected a reset pin on a µC, with the LED that's likely to be too small.

Get a closer picture from your scope without the cap so you see the actual bouncing times, to get an idea, the longer one we call 'bounce time'. Then choose a time constant, 5 times longer than the 'bounce time' could be a ball park. Then choose a cap so your LED resistor/cap time constant match that. To finis the design pick a resistor that ends that discharge fast enough so you are happy with it, say 10 times the other resistor so you get 50 'bounce times' to 99% discharge.

JS

[alsetalokin4017]

Hello folks,

I have this Picasso  https://snag.gy/hme2xG.jpg

The purpose of capacitor it reduce or eliminate bouncing the switch end the user wide button. On my oscilloscope I can see the effects of the capacitor but I don't know well I should parameter the equipment. On this print screens, https://snag.gy/KIcTe6.jpg and https://snag.gy/5ApnSw.jpg you can see  the wave signal with capacitor 10uF and without capacitor. But to achieve this signal wave I need parameter time/div in 1 second per time. I need wait a second to can see have shape each time the button is pressed.

I am configuration the equipment well?

Use the Horizontal Position control to move the trigger point over to the left edge of the screen trace area. Use Trigger Level control to set trigger level a little higher than 0.

Also try using the Single Shot sweep mode. Get ready, push SINGLE button on scope top right, then push your "user wide" button. Sweep should start and run one screen then stop.