What relay?

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
Am I missing something here or what! Doesn't the schematic do that posted in #18 except now for 240vac?
SG
Thanks for your help sghioto the schematic seems to work; but Yes you are missing something here ;). We first discussed using the gateway and a relay because power delivered straight from the gateway may effect the running of the fan, so that remains as per the scheme. We next discussed what exactly to use and where to source it from so what gateway and what relay and where to buy them. Any ideas? Thanks again
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
Thanks for your help sghioto the schematic seems to work; but Yes you are missing something here ;). We first discussed using the gateway and a relay because power delivered straight from the gateway may effect the running of the fan, so that remains as per the scheme. We next discussed what exactly to use and where to source it from so what gateway and what relay and where to buy them. Any ideas? Thanks again
Actually looking at I think that there is a slight error in schematic. I think the hot supply before the dimmer should supply into the TRIAC rather than the really and the TRIAC should supply the relay when triggered? I also don’t think a TRIAC carries a neutral ?
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
Where are you located and what electronic suppliers do you use?
Thanks so much for your advice on this very excited about putting this together. I looked up TRIAC and found someone who supplies loads of types. Here is the link what do you think might work?

https://uk.rs-online.com/mobile/c/semiconductors/discrete-semiconductors/triacs/?pn=2

We are running on 240v don’t know if u need more info that that?

this may be a dumb question but just so I am getting this right. Based on the diagram below.

Pin G is the gateway wired from the switched live.

A1 can be a permeant live / hot feed from before the dimmer switch

A2 would feed to the re

7C881BF7-25AB-4C91-9C43-C7C88F8C2E46.png
thanks in advance
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
What gateway? Is that the dimmer? This is the first I've heard of a gateway.
SG

Wrong! Can be wired either way.
The TIRAC gateway...

Actually not wrong in this case if I’m not mistaken. The TIRAC has 3 pins perhaps they can be wired to neutral but in this case I don’t think neutral is required.

One pin is the gateway controlled by the switched live after the dimmer.

One pin is the hot feed in from before the dimmer and

one pin is the voltage out to power the relay.
?
Im new to this so I’m not sure but I think that is how this is working in this set up?
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
In my post #31 MT1=A1 MT2 = A2, G= Gate, only three connections.
SG
Got it I think. As per your diagram The hot live feed goes to the relay - then to the TRIAC - the neutral is wired to the TRIAC - the gate when triggered by the switched live allows the flow of current through the TRIAC completing the circuit and activating the relay ?
 

sghioto

Joined Dec 31, 2017
1,313
the gate when triggered by the switched live allows the flow of current through the TRIAC completing the circuit and activating the relay ?
Correct, but can't help thinking there's no need for the triac if there is what you call a "switched live". Again what is this "switched live" and why it cannot be connected directly to the relay coil?
SG
 

crutschow

Joined Mar 14, 2008
25,247
I just realized there's a fly in the ointment.
The TRIAC won't trigger until the dimmer triggers, which means the TRIAC output will be essentially the same as the dimmer output. :oops:

Back to the drawing board.
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
Correct, but can't help thinking there's no need for the triac if there is what you call a "switched live". Again what is this "switched live" and why it cannot be connected directly to the relay coil?
SG
So switched live is a live that runs to an appliance in this case lights to a switch then to the lights allowing the switch to control the lights. Hope that makes sense. The relay can’t be connected directly because before the switch the wire is hot and the relay would be on all the time so the fan would be on all the time after the switch the voltage varies and effects the fan.

so the problem is to control the fan on and off from the dimmer switch without the the dimmer effecting the fan. At present if u dim the lights the fan drops in power as the dimmer drops the voltage. I hope this is clear?
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
I just realized there's a fly in the ointment.
The TRIAC won't trigger until the dimmer triggers, which means the TRIAC output will be essentially the same as the dimmer output. :oops:

Back to the drawing board.
Humm, I think it will work no? The dimmer just provides voltage to open the gate. This only needs to be a low minimum voltage say 1.5v so the dimmer would hold the TRIAC open when on no matter if dimmer or not. A hot feed to the Relay / TRIAC can be taken from the switched live before the dimmer or if this is a problem from a permeant live somewhere else. Would it not work?
 

Tonyr1084

Joined Sep 24, 2015
4,889
Devil's advocate here - - - why does a fan need a continuous 120VAC and a switched 120VAC? I'm thinking something is fundamentally wrong with the premises of using a control voltage to control a live voltage. It (assumably) would work just to switch the main power to the fan. But from all the posts I've read so far - it sounds like you want to control a simple fan from a dimmer switch, but the dimmer switch is not rated to control the fan. Hence, the fan's operation is not normal. My neighbor tried that and asked me why his fan was making a funny noise.

So I'm thinking you want to be able to control the lights without affecting the fan. When the lights are on at any level, the fan still operates at the normal voltage. Is that true? If so, can you share with us what dimmer you're trying to use and what fan you are talking about. Honestly, I've never heard of a fan with power but only switched on when it's powered. I think we've gone 54 posts into this thread without having the correct details.
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
Devil's advocate here - - - why does a fan need a continuous 120VAC and a switched 120VAC? I'm thinking something is fundamentally wrong with the premises of using a control voltage to control a live voltage. It (assumably) would work just to switch the main power to the fan. But from all the posts I've read so far - it sounds like you want to control a simple fan from a dimmer switch, but the dimmer switch is not rated to control the fan. Hence, the fan's operation is not normal. My neighbor tried that and asked me why his fan was making a funny noise.

So I'm thinking you want to be able to control the lights without affecting the fan. When the lights are on at any level, the fan still operates at the normal voltage. Is that true? If so, can you share with us what dimmer you're trying to use and what fan you are talking about. Honestly, I've never heard of a fan with power but only switched on when it's powered. I think we've gone 54 posts into this thread without having the correct details.
hi so the fan is an in line extractor with a timer it’s not uncommon. It has a permeant live and a switched live. The switched live turns it on and powers it while the switch is turned on (assuming this). When the switch is turned off a timer kicks in and the fan is powered from the permeant live (assuming this). In any case no need to worry about the permeant live to the fan because this is not a problem. The problem is the switched in relation to the dimmer.
 
So then, to recap your fan: Has power. When started it runs. When the need for it to stop is switched off the fan still runs for a set period of time.

A relay might find a use in your project, but you may need to build some other sort of controlling system. You're working with mains voltages, which is dangerous to human health and life. It's also a possibility the thread may be outside guidelines of this website. It's not my decision to make and I wouldn't want to.

You might need to build some sort of voltage detector that can detect the presence of line voltage (full OR dimmed) and activate a control circuit. I'm just guessing now - but I'm thinking that when you set your dimmer to anything less than full on the fan's behavior becomes unreliable. So the question is how to build a detector. Another part of that question is what to put it in or where to mount it.

Since there's a constant 120VAC source at the fan, you could use that as your "Trigger" source. Located at the fan you can put a box containing circuitry that is wired into the lighting system and detect the presence of 50/60Hz AC. When detected, the circuit activates a relay (we're back to a relay but can be other devices as well). When activated the fan sees the 120VAC control and turns the fan on. When the 50/60Hz AC is gone, the relay (for now) drops out and the fan times out at whatever extended time period is set.

A better understanding of the device and functionality is helpful. I think we can probably come up with a better solution than trying to solve the problem as you presented it. I'm not saying your question is a bad one, just thinking that there's a better way to solve the problem than the approach you had in mind.
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
So then, to recap your fan: Has power. When started it runs. When the need for it to stop is switched off the fan still runs for a set period of time.

A relay might find a use in your project, but you may need to build some other sort of controlling system. You're working with mains voltages, which is dangerous to human health and life. It's also a possibility the thread may be outside guidelines of this website. It's not my decision to make and I wouldn't want to.

You might need to build some sort of voltage detector that can detect the presence of line voltage (full OR dimmed) and activate a control circuit. I'm just guessing now - but I'm thinking that when you set your dimmer to anything less than full on the fan's behavior becomes unreliable. So the question is how to build a detector. Another part of that question is what to put it in or where to mount it.

Since there's a constant 120VAC source at the fan, you could use that as your "Trigger" source. Located at the fan you can put a box containing circuitry that is wired into the lighting system and detect the presence of 50/60Hz AC. When detected, the circuit activates a relay (we're back to a relay but can be other devices as well). When activated the fan sees the 120VAC control and turns the fan on. When the 50/60Hz AC is gone, the relay (for now) drops out and the fan times out at whatever extended time period is set.

A better understanding of the device and functionality is helpful. I think we can probably come up with a better solution than trying to solve the problem as you presented it. I'm not saying your question is a bad one, just thinking that there's a better way to solve the problem than the approach you had in mind.
Yes understood. I would absolutely be up for exploring the possibilities of the above. To add a trigger to the switched live or the lights that triggered a suply form an permeant source is what I am trying to do. Any ideas? What about TRIAC for this in this ? Just to add it’s the UK so we are 240v all over including lighting circuits.
 

sghioto

Joined Dec 31, 2017
1,313
This detector might work using a sensitive gate triac. It all depends on the voltage available when the dimmer switch is at minimum brightness. Basically rectifying the ac across the lights to a DC voltage to trigger the triac.
SG
EEE Fan control.png
 

Thread Starter

StuManFlu

Joined Sep 15, 2020
39
This detector might work using a sensitive gate triac. It all depends on the voltage available when the dimmer switch is at minimum brightness. Basically rectifying the ac across the lights to a DC voltage to trigger the triac.
SG
View attachment 217450
this looks good thank you. Can you talk me through it? Sorry to ask, if I’m going to put it together I need to understand.

R1 is a 20k resistor
D1 is a diode
C1 is a capacitor
R2 is a 100k resistor

Can you tell me what they all do?

I think the voltage from the dimmer will be pretty high. We work at 240v maximum and I believe a TRIAC can work at a trigger voltage of 1.5v so seems very likely to me that the dimmer would hit the 1.5v trigger voltage fairly quickly and kick on the fan. I’m assuming this, what do you think?
 
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