Switch Debouncing

[@skunkybuilds]

The white board analogy is MONEY! good stuff man! keep it up! Your way of explanation is very easy to understand practical! LOVE IT

[@0033mer]

Thanks for the feedback

[@Александр-р3э3м]

From the first two minutes, we can see that the video of really helpful and useful. Thanks!

[@noweare1]

Very good info. I am also a fan of debouncing via hardware.

[@naveengupta5588]

Extremly useful video.... Explained very nicely thank you so so much 😇

[@0033mer]

You're welcome!

[@edgeeffect]

I'm here trying to learn how to denounce my (vintage) contacts without killing them... Great stuff here. :) It's nice to see FORTH making a comeback... I was really into FORTH back in the 1980s...

[@0033mer]

Check out my channel for more projects coded in FORTH.

[@serpih]

Very nice explanation. I use an Arduino to open a door, and I have some problems with electrical noise, the door open alone every 2 days or something. Your software solution will help me with the next project, to finish with electrical noise and bouncing.

[@0033mer]

Glad it helped

[@perseverance8]

Interestingly “switch bounce” isn’t ONLY a physical “bouncing” derived issue, some of the “bounce” is caused when the switch contacts get close enough together to allow even low voltages to jump across the gap through air when the contacts are close enough to reach the respective breakdown point of air to jump the gap, this can be seen on an oscilloscope when the initial “bounce” shows up then you’ll notice when the first contact of the switches metal contact surfaces conduct through the much lower resistance of its metal contacts.

[@beaconing7689]

nice explanation, easy to understand 👍

[@0033mer]

Glad it was helpful!

[@t1d100]

Great video!

[@0033mer]

Thanks for the visit

[@4623620]

Is it the Motorola version MC14490 that is available and pricey ? Because there is also a DIP16 version made by ON, maybe better available and not so expensive (year 2020).

[@talash1751]

is it possible that denounce time change over time for a switch. Let's say if I eliminate debounce in SW then should I have to add some factor of time in it ?

[@thromboid]

I'm trying to use an MC14490 for debouncing a rotary encoder, but can't get the built-in oscillator to start up. It's an SMD part (soldered onto a DIP breakout board), but the datasheet says these have the same pinout as the DIP version. The datasheet says the inputs have pull-up resistors, but also to connect any unused inputs to Vdd or Vss, which seems odd. It's also not clear about the need for decoupling (I've tried with and without). I have two chips and neither one seems to be working. Any suggestions? Thanks!

[@0033mer]

First check the obvious. Proper supply voltage from pin8 to pin16. A .1 uf decoupling cap across supply pins. The value of the external capacitor across pins7 and 9 should be larger than 100pf. What value are you using? I usually use a .001 uf cap. After power up you should see a clock signal on pin9.

[@thromboid]

Thank you for the quick reply! 5 V at pin 16 wrt pin 8, and I've reinstalled the supply decoupling. I've tested with a couple of 0.0015 uF caps for Cext (that's "152" marking, right?), both film and MLCC, leads as short as I can go for breadboard use. Eventually I noticed strange resistance readings across the breadboard - tens or occasionally hundreds of ohms where there should be continuity! I think the board had some flux spill on it, and maybe that soaked up the backing adhesive or something. Pretty weird. :) I tried again with a good breadboard but still no clock signal, with just over 0 V on pin 9, and about 1.5 V on pin 7. However, I did successfully test it using an external clock (1 kHz from my scope) into pin 7 (and I could see a lower-voltage copy of the signal on pin 9). I had to lower Vdd to about 4 V to match the scope's clock signal level. What would you normally expect to see on pins 7 and 9 with no capacitor installed?

[@thromboid]

Just an update: I didn't manage to get either of those SMD 14490 chips to work...maybe ESD or thermal damage while soldering onto the breakout board, I don't know. But I did get some NOS DIP 14990s on eBay and the circuit worked with one of those. I made a little stripboard module and installed it into my Marshall JMP-1 guitar preamp to help with the jittery encoder (a common problem). While testing I discovered that the encoder wasn't switching reliably, but some contact cleaner sorted that out. :)

[@貓頭鷹-j8l]

his explanation makes me feel sleepy

[@70925007]

At 6:10 do i connect both ends of the schmidt trigger to the input?

[@0033mer]

The switch is connected to the input of the schmitt trigger and the output will be bounce free driving other circuitry.

[@70925007]

@@0033mer no I meant both inputs connected together

[@0033mer]

Yes ...If you are using a NAND gate, tying the inputs together will make it an inverter.