Simple Wifi switch

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Re: Simple Wifi switch

By trackerj
- Thu Feb 26, 2015 8:27 am #10792
spy king wrote:The need is based on the fact that I am to lazy to turn on my Hifi setup and sometimes forget to turn it off which isn't to good for my tube amp.
The switch idea isn't something radically new, but I would like to make this a little more self contained.

Tentative parts list.
I would like to go all out and design a board, but this would probably be cheaper as it's only one off.

I would like to plug all these together, and stuff it into an power switch

Looking forward to inputs on what you guys think!


First a WARNING!! You will play with LIVE MAINS!! Deadly zone!!

Easiest way to do it, is to use a MOC optocoupler + Triac combination.
Usually for ON-OFF only jobs (no dimming required) I use MOC3041 for optocoupler (Zero voltage crossing one) and a good quality Triac, sized by the power needs or as big as available. 25A one usually fits mostly of the needs in such a project like yours, with decent power disipation. For standard lighting, 8A is 99% of the times enough.

BT1XX class from NXP never dissapointed. Be sure they are genuine, from a trustable source. LIVE MAINS Switching!!
http://www.nxp.com/documents/data_sheet/BT137-600.pdf
https://www.fairchildsemi.com/datasheets/MO/MOC3043M.pdf

Don't know how to directly upload a picture here (or if is possible), to show you such a module. Found it, was confused by the new Forum look&feel :). Just see below a quick one:
CBDB_Board_Mains_Switching - optocoupled Triac.jpg

BT137-600 - Triac.jpg


Be carefully also to the PCB if you design it yourself. LIVE MAINS Switching!!

If is interesest on the subject I can elaborate more :)[/quote]
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Re: Simple Wifi switch

By trackerj
- Fri Feb 27, 2015 4:03 am #10862 If somebody want also to see how is working, I've done a quick CBDB style setup for a short video:

http://youtu.be/mfYOBolDxJU
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Re: Simple Wifi switch

By trackerj
- Fri Feb 27, 2015 11:55 am #10899
spy king wrote:That does indeed look good.

What is the advantages/disadvantages of a triac vs a relay in this case?


Honestly I don't see any disadvantages of using a Triac or SSR. Any. First of all Triacs are solid-state devices, whereas relays are electromechanical devices. Electromechanical device, means a coil and some moving parts. And a mechanical contact. For more details I'm sure you can find tons in information on Internet.

To sumarize, and is not necessary an exhaustive list:

Advantages of the triac:
- No mechanical wear-out
- Easier to switch on zero-crossing. (Can also be done with a relay, but less accurate due to the switch-on delay)
- Can be used in dangerous environment, particularly in explosive sensitive environments where sparking relay contacts are absolutely out
- No EMI due to switching sparks/arcs
- No contacts which can weld
- Often more compact
- No magnetic interaction with nearby inductors

Advantages of the relay:
- Can handle DC (not your case)
- Can handle any signal: low and high current, low and high frequency, low and high voltage
- Insulation between control and switched sides (done for Triac by the Optocoupler )
- No leakage when off
- Very low voltage drop when on
- high currents possible without cooling
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