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/diy/ - Do It Yourself


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1185123 No.1185123 [Reply] [Original]

Do you trust Chinese relays?

>> No.1185129

For wall voltage? Nope.

>> No.1185132

it all comes from china now. you dont got much choice. Just need find good quality is all.

>> No.1185133

sure, why not. the relay is a solved problem, it's 180 year old technology, it's impossible to fuck up.

what i don't trust is chinese power ratings. one horsepower my ASS.

>> No.1185140

Why do I hear a relay actuate when I visit wellsfargo.com

>> No.1185144

>>1185133
Relay for an electric motor rated at 1hp?

>> No.1185192

>>1185132
I meant Chinese-designed relays, not relays from established manufacturers like Omron or Crydom that happen to be manufactured in China.

>> No.1185243

>>1185192
>Chinese-designed

No such thing.

>> No.1185256

>>1185123
>using relays in 2k17

>> No.1185257

>>1185256
you shouldn't relay on them?

>> No.1185259

>>1185257
SSRs and MOSFETs in general are the superior option in 99% of diy use cases
>quiet
>fast switching
>less power consumption
>mechanically robust, not sensitive to vibration
>longer life time

>> No.1185261
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1185261

Originally? No. Now I'm not so sure.

>have 120/240 relay for use on my sous vide
>turned it I and let it come up to temperature from cold tap water, around 15 gallons of water
>set it at 80deg C and walked away
>come back and all the wires are hot, burning plastic and electronics smell coming from relay, the relay label is melted and the potting compound melting out of it, and it's locked in the "on" position
>water is at 90deg C
>unplug everything!
>let cool down
>attach 2 huge heat sinks to the relay
>turn back on after 5 minutes
>good as new
>MFW

All in all, happy.

>> No.1185275

>>1185261
>Relay is misbehaving and damaged
>Stick a heatsink on it

>> No.1185288

>>1185259
Except that making a solid state switching device with comparable ratings is more expensive, you can't just put a mosfet instead a relay most of the time, power ratings, and cost effectiveness and all that.

>> No.1185293

>>1185257
Fucking hell carlos

>> No.1185294

>>1185288
but this price difference only matters when you are going to massproduce whatever you're building
a SSR that is designed for 20+A mains AC costs about $15 from a reputable local supplier or $3 from china
a comparable mechanical relay will be about $3 locally or $1 from china
so while the cost difference is significant relatively, absolutely it doesn't really matter on one-off projects
and when you switch DC, which is much more common on diy projects
you can use MOSFETs directly and they are even cheaper than traditional relays

>> No.1185295
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1185295

>>1185144
yeah that's what i'm saying, the 'motor horsepower rating' the chinks print on relays is pure fantasy.

if a relay's going to survive switching a 1hp induction motor, it needs to be the size of a flip phone, not a sugarcube.

>> No.1185300

>>1185294
>cost difference is significant relatively, absolutely it doesn't really matter on one-off projects
You're on a board where some people pull resistors from old junk to save money.
And if you're going to run your 20A SSR anywhere near its maximum rating, you'll need a heatsink, which not only costs more, but also takes space.

>> No.1185335

>>1185300
>You're on a board where some people pull resistors from old junk to save money.
those people won't be playing with kilowatts of AC
so they can use mosfets for their small DC projects and even save money compared to relays

>And if you're going to run your 20A SSR anywhere near its maximum rating, you'll need a heatsink, which not only costs more, but also takes space.
But it won't be on any diy project
domestic circuits over here are fused at 16A that gives you about 3.5kW (or 11kW on three phase) to play with
what project do you have in mind that draws this much power but doesn't have space for a 100x50x50mm heatsink
and at such a low budget that $15 for the ssr and a $5 heat sink have a significant impact?

for example I'm using that mentioned ssr on the heat bed of a 3d printer at 450W and about 2A no heatsink is required
and $15 compared to $250+50 for the chink printer plus bed itself is negligible

>> No.1185344

>>1185261
>>1185275
You're supposed to cool relays you knuckleheads

>> No.1185422
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1185422

>>1185335
Are you joking or something? Well, I'll bite.

>those people won't be playing with kilowatts of AC
Kilowatts or not, they need something for switching. And mechanical relays are cheaper.
>But it won't be on any diy project
It was you who wanted to use a 20A relay as an example.
Not that the situation is much different when a Burger wants to control his coffee maker or do something like >>1185261.
>what project do you have in mind that draws this much power but doesn't have space for a 100x50x50mm heatsink
>and at such a low budget that $15 for the ssr and a $5 heat sink have a significant impact?
Pic related or any variation of it, for example. Or anything requiring multiple outputs, capable of switching higher currents if needed. There are plenty of applications where SSRs are just bigger, more expensive, produce more heat and are more vulnerable to random surges without offering any practical benefits.
>for example I'm using that mentioned ssr on the heat bed of a 3d printer at 450W
20A SSR for a 2A load? Yeah, no wonder it doesn't need a heat sink.
Well, that's a reasonable application for an SSR. I wouldn't use a mechanical relay for a small heating controller either. Point being, SSRs have their own advantages and mechanical relays have their own. It is retarded to religiously stick to one or another.

>> No.1185467

>>1185422
I'm with you buddy, any home appliance or project can use relays by using a 10$ transformer (if required) and a 10$ relay.

>> No.1185492

>>1185344
>damaged
>stick a heatsink on it

Is there anything else a heatsink can magically fix? Leaking pipes? Bones? Poor soil quality?

>> No.1185894

I find them very relaying