Question about power rating clickie.

I have a host with a clicky rated at 1.5A 220V. Does it mean I can't go higher than 1.5A current even at 4-8V ?
The clickie looks heavy duty, nothing like the pen laser clickie or the C6 clicky.

I dont think its an issue. I was under the impression that its the power that counts ie 330 W so you should be able to go higher without probs. :beer:

Edit: wasnt quite right there DC is different to AC for switches have a read here: http://www.electro-tech-online.com/general-electronics-chat/33332-dc-switch-ratings.html and here: http://www.kpsec.freeuk.com/components/switch.htm

For low voltage electronics projects the voltage rating will not matter, but you may need to check the current rating. The maximum current is less for inductive loads (coils and motors) because they cause more sparking at the contacts when switched off.

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Having said that Ive used 3 A 240 V switches for 6-8 A 12 V systems before and havent had any issues....

People use the C6 switch with a 1.8A linear driver all the time. I suppose this twice a big switch should handle several amps without problem at 4V.
Is there a way to test it with a bench psu ? My psu can go to 5A.
Connect both lead of the switch to the PSU and click 100 times fast ?

A 1.5 amp switch can only handle 1.5 amps. It doesn't matter what the voltage is It's the resistance of the switch contacts.

Current is how fast power flows through the switch. The voltage is just how much pressure is pushing it through.

The switch is rated at 1.5 amps, it doesn't matter how much voltage is needed to "push" this 1.5 amps through the switch, the power heating the switch up ("I squared R" loss) is the same!

If the resistance of the switch is 1 ohm then:
1.5 amps will cause (1.5x1.5)x1 = 2.25 watts of heat.
3 amps will cause (3x3)x1 = 9 watts of heat.

piferal is correct, DC doesn't switch off 50 times a second, so a swich rated for 220V AC may only be rated for 60V DC. But with only 4-8 volts it's not a problem.

Buy a new switch, or don't use it to switch the power.

The switch is brand new in the host. I want to deliver 1.9A to a H1600 diode. The power will be provided by two Ben Boost driver with 3x 18650 in parallel. That means the current at the switch will be approximately 2.5-3A ! I suppose it will work fine.

The smaller switch is from a pen laser.

Don't replace it unless it's giving you problems. You'd cry if you saw the switches that come in many cheap hosts. I bought a cheapo baggie of replacements, the leads break if you bend them twice, i.e. if you bend them, and then bend them back to where they were, they snap. That one you have, by comparison, looks pretty beefy. A low resistance switch such as a mcclicky costs about $7 (dunno its specs, but I hear it can do 3A just fine), and is the go-to choice for a standard clicky. A FETtie costs a bit more, but handles at least 25A in its current revision. McClicky, if it fits, might be an option if this switch has too much resistance.

Of course it depends on how safe the manufacturer was in rating the switch.

Do they rate for 1/2 the current it fails at, 1/4 the current it fails at, 1/10 the current it fails at?

All I can say is it will be 100% safe at 1.5A. It may or may not be safe at 2.5-3A. I would say it probably would be, but the manufacturer won't gaurente it at more than 1.5A.

AUS said:

A 1.5 amp switch can only handle 1.5 amps. It doesn't matter what the voltage is

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That simply isn't true. Try switching a 30kV 30mA circuit with that thing and let me know how it goes.

Cyparagon said:

That simply isn't true. Try switching a 30kV 30mA circuit with that thing and let me know how it goes.

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Yes, that statement taken on its own is incorrect. However I did qualify that by saying:
"piferal is correct, DC doesn't switch off 50 times a second, so a swich rated for 220V AC may only be rated for 60V DC. But with only 4-8 volts it's not a problem. ".

The question was in relation to current rating at lower voltage.

However for the sake of being thorough, let me restate it thus:
"A switch's AC voltage rating must be de-rated to a lower DC voltage because of the higher danger of arcing at DC, and the current rating cannot be safely exceeded no matter how low the voltage"

I just had a look through my switches and relays. Many of them have ratings for 250VAC, 125VAC, and 30VDC. The ratio tends to fall somewhere around 1:1.7:1. A couple had ratings for all of the above and 100VDC, and the 100VDC current rating was less than 1/8th that of the 30VCD rating. I would assume you can interpolate this to mean the rating at 8V is higher than the rating at 30V.

Therefore, I would guess your switch would be good for at least 1.5A at 30VDC and even more at 8V. Realistically, you can exceed the rating anyway. That just means it fails at half a million clicks instead of 5 million or whatever. And in a pointer where you over-drive the piss out of it where it only lasts a hundred hours - who cares? The diode will fail before the switch.

Worst case scenario is it melts. So what? Just replace it - no harm done. I'd try it. It'd be a bad idea to exceed ratings at line voltage because it can cause damage/fires/death/warts/diabeetus, but low voltage like this isn't critical.

There was a thread here where a guy was using a dip switch (rated for ~50mA?) to switch his 1A lm317 and it worked fine

Cyparagon is right.

You best look at the total apparent power being passed by the switch as a guide.

230V x 1.5= 345W

Now its not going to handle 3.45V @ 100A and its not going to handle 34.5kV @ 10mA, there are factors of insulation resistance, arc gap between switch contacts, switch resistance & cross sectional area of the switch contacts to consider.

Id put it in and forget about it.

While there are "rules of thumb" such as "the DC amp rating of an AC switch should be valid up to 30VDC" it will depend a lot on the switch itself. Some switches have orders of magnitude worse DC amp ratings than AC amp ratings. Whereas AC cycles through zero 120/s, DC is always on. Switches made for DC usually have many smaller contacts in order to reduce the time that arcing occurs, and therefore reduce the amount of heating that can damage the switch contacts. You're actually using quite a bit of current in your builds, so if you can maybe seek out a switch with an actual VDC rating.

You'll also encounter anecdotes about switches working fine using the rule of thumb. They probably do, but the switch's contacts are still being degraded by the stress caused by the VDC. We have our own "rules of thumb" for exceeding our laser diode specifications too.

Bionic-Badger said:

Some switches have orders of magnitude worse DC amp ratings than AC amp ratings.

Click to expand...

Really? Link?

Cyparagon said:

Really? Link?

Click to expand...

Here are some NKK switch electrical derating calculations. Here's also an article. It depends on the type of load and voltage. So if you're going to use a Flexdrive you don't even need to worry about any of the derating because it has a soft-start; a lamp load acts like a short when it's first on, so the switch has to deal with a huge surge, etc. So when you're derating... well, it depends on what you're doing.

HAH!, my favorite part is when they have values for driving capacitive and inductive loads with DC. Good luck with that. :crackup:They have a fundamental misunderstanding of most of the AC load types, too.

Lamps aren't shorts. Go measure the resistance of a light bulb - it's not zero. Sure, the inrush current can be a few times steady-state, but it's for a measly few milliseconds.

All DC loads are resistive. If you put an inductor on a DC source, either the source or the inductor blows up. If you put a capacitor on a DC source, either nothing happens, or the DC source blows from the inrush current if the cap is particularly large.