this post was submitted on 20 Jun 2023
13 points (100.0% liked)
Ask Electronics
3173 readers
2 users here now
For questions about component-level electronic circuits, tools and equipment.
Rules
1: Be nice.
2: Be on-topic (eg: Electronic, not electrical).
3: No commercial stuff, buying, selling or valuations.
4: Be safe.
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Every material has resistance.
You can calculate a materials resistance using its resistivity and dimensions. For a simple wire, the formula is R = p*l/A, where p is resistivity, l is length, and A is area (cross sectional. Imagine cutting the wire, you'd see a circular cross section).
Some materials like copper have very low resistance.
Some materials like oil have a very high resistance.
Some materials like carbon have a resistance somewhere in between, but generally fairly high.
Resistors use a strip of carbon to make a high resistance path.
Resistance in a switch is typically minimized by design, so introducing a switch or button should not introduce a lot of resistance. It is tyically better not to use switches of this type in signal critical or high power applications (e.g. sound or battery charging), but charging up a small capacitor or powering a small dc circuit should be fine
To measure resistance, one can use a multimeter. This makes use of Ohm's law. Ohms law shows that
V=I*R
Where V is voltage, R is resistance, and I is current. When a small voltage is applied across your component, the current is measured. Then using the current and voltage, it can figure out what the resistance is. It shows it to you on a display so all you have to do is touch the probe tips to the two legs of the switch.
For a switch this will typically be less than 1 ohm. If you buy from a reputable distributor (e.g. digikey, mouser, arrow, farnell, even LCSC) you can get the "datasheet" and look for the constact resistance. This might be a bit harder with ebay/amazon/aliexpress parts, so just stick with a multimeter.
A cheap handheld one is fine, but I'd say prob look for an EEVBlog or other video looking at good cheap meters; you can get pretty good stuff without breaking the bank. Don't stress over it though; any multimeter is better than no multimeter
Awesomesauce! This is exactly the clarification I needed as I unfortunately got my part from a less "reputable", that being Temu, source.
What are you switching? There’sa good chance (but no guarantee) even an ultra-cheap switch is fine.
A 12 volt battery w/ a pot and a few other components. The plan is it wont be running more than 5 milliamps through it. I ended up getting this so not exactly a conventional momentary switch.
That is pretty much exactly a conventional momentary switch. It just happens to be packaged for use controlling something a little different.
It should be fine for your application.
One thing to note - the contacts will probably "bounce" as the switch is closed. Produce a string of momentary connections and disconnections for, oh, say the first few thousandths of a second. That's perfectly normal for a mechanical switch.
That won't matter in its intended application. But if you are using it with electronics, say counting the number of times the switch is operated - the results can be unexpected.
You can look up "debounce" to see how this can be worked-around.
Thanks, I appreciate the clarification on the switch just having a different housing. I'll have to do some further research on "bouncing", interesting stuff.