Author Topic: KCD-11 rocker switch from aliexpress is junk  (Read 2863 times)

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Offline dusanTopic starter

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KCD-11 rocker switch from aliexpress is junk
« on: April 21, 2024, 08:30:02 am »
I recently had troubles with KCD-11 switches I bought on aliexpress (https://www.aliexpress.com/item/1005001513148147.html), they had 100s of ohms ON resistance. I don't think I used them much, maybe few hundred times. I dissasembled it and found that the seat have worn spots in nickel plating where the botom of the plate is touching the center pin. I did paid $1/10pcs free shipping so, I don't know what I expected. Rant over.
 

Offline dusanTopic starter

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Re: KCD-11 rocker switch from aliexpress is junk
« Reply #1 on: April 21, 2024, 09:29:17 am »
Here's frequency measurement before (yellow) and after switch replacement (cyan)
 

Offline BrokenYugo

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Re: KCD-11 rocker switch from aliexpress is junk
« Reply #2 on: April 21, 2024, 01:17:06 pm »
Yeah definitely don't go too cheap on switches, bad contacts, melty cases, etc.
 

Offline thm_w

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Re: KCD-11 rocker switch from aliexpress is junk
« Reply #3 on: April 25, 2024, 09:03:38 pm »
The thing is some suppliers with the exact same looking part might be great. But yeah these look cheap.

LCSC has some from 10c each that I'd probably trust more: https://www.lcsc.com/product-detail/span-style-background-color-ff0-Rocker-span-Switches_SHOU-HAN-KCD11-2P-R_C5884414.html (hundreds of options just picked the first one).
Profile -> Modify profile -> Look and Layout ->  Don't show users' signatures
 

Online Kleinstein

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Re: KCD-11 rocker switch from aliexpress is junk
« Reply #4 on: April 26, 2024, 06:38:27 am »
Mechnical contacts can be tricky with small signals. A good low ohm contact may need a certain minimum current to flow.
The switch could well be OK for other uses (e.g. to switch a light or possibly even mains).

The construction looks cheap, with no extra contact material. The problem may not be the worn spot, but possibly just an oxidized or oily contact surface.
 

Offline Stray Electron

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Re: KCD-11 rocker switch from aliexpress is junk
« Reply #5 on: April 26, 2024, 03:19:47 pm »
Mechnical contacts can be tricky with small signals. A good low ohm contact may need a certain minimum current to flow.
The switch could well be OK for other uses (e.g. to switch a light or possibly even mains).


  X2.  The OP should look up the term "sealing current" or "wetting current".   I found out about this early in my career when I tried to use a normal AC switch in a low current digital circuit.  A digital rated switch was about 3x the price but it worked and a standard switch simply wouldn't, even when brand new.

   Also on those Chinese made switches it very likely that the contacts were made of steel and had a very thin layer of tin on them and that the plating wore through very quickly. I've found that to be VERY common in cheaply made wire, bulbs, sockets, switches, etc. 
 


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