B3F-4055 switch bounce

[Ioannis]

I suppose you have only a switch and a resistor, right?

Either you got a perfect switch or the scope is slow enough with low memory depth.

I will do a similar test. Maybe you have to use 5ms/div or lower?

Ioannis

[richard]

i would not expect to see any "bouncing" at 50mS per div , @ 0.5mS/div you are more likely to see something

[Demon]

i would not expect to see any "bouncing" at 50mS per div , @ 0.5mS/div you are more likely to see something

I went back and redid the tests. Here's the falling edge of a SR-25 rotary switch on a BK Precision 1560 at 1ms:



(Let me know if there's a better setting for the scope. I just went with trial and error.)


And the rising and falling edges on the DSO-TC3 at 1ms:





It's not even remotely close to similar. I should have started testing with the BK; its buttons aren't making the screen jump around.

The Tektronix 466 was giving mismatched readings; giving a jagged trace, then curves, then just dropping on/off. It would need a serious cleaning, which I can't afford. And that wouldn't repair worn switches and pots, they'd need to be replaced. Let alone if there's fried circuits in there. I figure the old owner got rid of it for a reason.


Here's a pic of the SR25 switch. That wiper seems to bounce a lot as it moves out of one position and into another.

[Ioannis]

Well we expected the BK screenshot response. That is what a good switch bounce should be!

The Fnirsi I guess is either for the recycle bin or has some settings to smooth out the ripple so much that looks like a perfect rect wave.

The SR25 switch, depending on their oxidation state, since the contacts are very much exposed, is normal to have such a behaviour.

Ioannis

[Demon]

...The Fnirsi I guess is either for the recycle bin or has some settings to smooth out the ripple so much that looks like a perfect rect wave....

It's a toy to help teach electronics, nothing more. I'm starting my first return to AliExpress, along with those 3 DMMs that I tried out. I'll see how that goes.

EDIT: I was wrong about this device (next post).

...The SR25 switch, depending on their oxidation state, since the contacts are very much exposed, is normal to have such a behaviour.

Ioannis

This one is brand new though; straight from the manufacturer 2 months ago.

Turns out this was caused by me touching the metal shaft. As soon as I installed a knob, that erratic bounce has mostly gone away. There's still a slight bounce, but nothing so drastic.

It did show to me though that the chinesium scope is useless to analyse signals adequately.

[Ioannis]

If any actuator has metalic case, it is wise that case to be earthed. Metals tend to work like touch sensors or antennas if not properly earthed.

Ioannis

[Demon]

Turns out it helps if you use a device properly, who knew.

The edge can be controlled by the little icon at top left, and SINGLE mode stops updating once triggered (you have to press RUN to reset).

I accelerated the sweep rate, which helped detect some noise but at least it's matching the old scope now.




It does have a few seriously good qualities: it's small, easy to deploy, and not overly complicated. Granted, the screen is small, but at least it can serve as a confirmation of what I see on the BK 1560.

One slight drawback, it seems to lag after a few minutes. It's as if internal storage has a problem managing all the data it accumulates. It gets progressively slower, it's very evident when you press the buttons (the beep gets progressively slower in response).

Still, it's not a bad buy. I'm definitely getting one with a larger display screen later.

[Demon]

If any actuator has metalic case, it is wise that case to be earthed. Metals tend to work like touch sensors or antennas if not properly earthed.

Ioannis

The MR0102 toggle on the right has a support bracket with 4 pins. I can easily ground those.

The SR25 SP4T on the left has no such pins.




I suppose I could pass an eyelet connector over the shaft and fix with a nut and then ground the wire to the PCB mounting screws. I have about 1cm of room under the knob; more than plenty for the plastic enclosure.

That will be a concern on the RV17 rotary pot; the shaft is short and I don't have much thread space. :/

[Demon]

Only the switch, says Omron underneath. Zero resistors or capacitors.

I wanted to do a baseline so I had something to compare any debounce circuitry.

I'm gonna test some other switch types and omron clones.

[Ioannis]

I suppose you have to add the whole circuit. Omron is a good company but in any case, mechanical switch always have a small time of bouncing.

Ioannis