Author Topic: Small Switch - Current Handling?  (Read 323 times)

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Offline LeoTech

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Small Switch - Current Handling?
« on: March 19, 2018, 01:20:48 am »
Hey everyone,

Quick question about small switches:

I am looking for a switch for my next project, and as I have almost zero experience with switches and current handling, I thought to ask here.

The switch in question is this one:


(Source: Muekra.de)

For several reasons, which are to complicated and unnecessary to explain here, I can only use this supplier and I am not able to find a datasheet for this switch.

So for my question: Will this switch be able to control/handle a current of max. 20 mA at 12 Volts?

Thanks in advance,

Leo

High School student with a passion and interest in electronics, both analog and digital!
 

Online Hero999

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Re: Small Switch - Current Handling?
« Reply #1 on: March 19, 2018, 01:44:08 am »
Impossible to know without the data sheet.

One of the problems with low currents is the oxide layer on the contacts may not be broken, when the contacts close. The current required to ensure the switch works reliably, is known as the wetting current, i.e. the minimum current which can be reliably switched.
 

Offline SeanB

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Re: Small Switch - Current Handling?
« Reply #2 on: March 19, 2018, 02:10:17 am »
That switch 20mA at 12V no problem short term. However long term those switches are not exactly the most reliable type, they, depending on the actual manufacturer, the choice of materials they used that day ( plastics and steel they use is very variable in quality, as it generally is a cheap recycled material with unknown quality control other than meeting some basic specs for dimensions and melting point) and just how worn the actual production tooling was. But, for a switch where under 500 operations is going to be the life, and you are not in any sort of aggressive atmosphere or too humid, it will generally do.
 

Offline LeoTech

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Re: Small Switch - Current Handling?
« Reply #3 on: March 19, 2018, 02:25:00 am »
Thanks for the answers!

Impossible to know without the data sheet.

One of the problems with low currents is the oxide layer on the contacts may not be broken, when the contacts close. The current required to ensure the switch works reliably, is known as the wetting current, i.e. the minimum current which can be reliably switched.


I've never heard of that, but it sounds plausible - although I doubt this will have any effect. If the current turns out to be to low, I can always increase it. I am more worried about the max current.

That switch 20mA at 12V no problem short term. However long term those switches are not exactly the most reliable type, they, depending on the actual manufacturer, the choice of materials they used that day ( plastics and steel they use is very variable in quality, as it generally is a cheap recycled material with unknown quality control other than meeting some basic specs for dimensions and melting point) and just how worn the actual production tooling was. But, for a switch where under 500 operations is going to be the life, and you are not in any sort of aggressive atmosphere or too humid, it will generally do.

500 operations is good enough for me, as this will be a one-off project sitting on my bench, and I can always replace the switch if necessary.
In terms of quality control, you are most likely correct, as this indeed appears to be a cheapo from China.

Thanks again,

Leo
High School student with a passion and interest in electronics, both analog and digital!
 

Offline Gyro

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Re: Small Switch - Current Handling?
« Reply #4 on: March 19, 2018, 04:03:23 am »
That switch should have no difficulty handling your maximum 20mA current, particularly at 12V (very low signal voltage can be more of a problem). It may not be of good quality but slide switches have good contact wiping action.

If in doubt, try it with an LED and series resistor and see if it flickers.
Chris

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Online Hero999

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Re: Small Switch - Current Handling?
« Reply #5 on: March 19, 2018, 04:58:31 am »
Thanks for the answers!

Impossible to know without the data sheet.

One of the problems with low currents is the oxide layer on the contacts may not be broken, when the contacts close. The current required to ensure the switch works reliably, is known as the wetting current, i.e. the minimum current which can be reliably switched.


I've never heard of that, but it sounds plausible - although I doubt this will have any effect. If the current turns out to be to low, I can always increase it. I am more worried about the max current.
https://en.wikipedia.org/wiki/Wetting_current
Looking at it again, you should be fine, with 20mA as it's a small switch.
 


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