I need advice on which RELAY to use in my circuit.

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
Im trying to build this lighting circuit for a light feature Iam building. Diagram attached. Let me give a quick overview . There are two circuits . Circuit 1 is led lighting strip circuit and Circuit 2 is a mains light circuit. What I would like to happen is when the wall dimmer switch is turned on in circuit 2, the completed circuit 2 will activate the relay in circuit 1. This will complete circuit 1. When the wall dimmer switch is powered off in circuit 2 . Then circuit 1 will deactivate also as the relay switching leg 3 loses power. See diagram attached.

This is wall dimmer I am using.

ttp://pages.ebay.com/link/?nav=item.view&alt=web&id=251655906936&globalID=EBAY-GB

Can you guys give me any advice on is what type of relay can be used to do this and if my circuit is sound

IMG_1769s.JPG
 

Kermit2

Joined Feb 5, 2010
4,162
the relay will be switched by the output of the dimmer? Do I understand your drawing correctly in this case?
That may be a problem. Relays that work from line voltage are common, but a dimmer can lower thst voltage into a range where relay operation is not possible. You need to insure your relay coil can receive full line voltage when you operate it. Variable voltage is not a proper drive for a relay.
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
you are correct the output of the dimmer in circuit 2 will be the switch for the circuit 1 . Ummmm is the a minmium amount of voltage that the dimmer can be set on to activate the relay to turn on circuit 1. eg 24 volts . would something like this work.

http://www.ebay.co.uk/itm/Latching-relay-board-with-either-1-or-2-pushbutton-inputs/111700865859?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=29973&meid=782ed5ac0bca43e6bacd6f0999b11879&pid=100005&rk=1&rkt=4&sd=121683644380&rt=nc
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
is there something else I could use instead of a relay then . all the componnet needs to do is switch on circuit 2 with current is detected on the 3rd trigger pin.
 

Kermit2

Joined Feb 5, 2010
4,162
if the voltage can vary so widely (24-240 VAC) then I am not sure there is a "simple" solution. Let us wait for more members to view this thread and see what answers they can provide.
 

dl324

Joined Mar 30, 2015
10,985
I'd suggest using an optoisolator to drive the relay and have the relay powered from circuit 1 240VAC. You could use a zener and resistor(s) to limit the maximum voltage across the opto LED.

Don't know if the ToS was changed to allow transformerless line powered posts...
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
Ok I have not heard of an optoisolator or optocoupler. But i found a video On youtube that explained it well.

I think this is heading in the right direction as the optocoupler can trigger circuit 1 powered on 240VAC. But I will need to find a relay with an Optocoupler built in . The one below does what I want for circuit 1 but doesnt take in 240 VAC for circuit 2. It requires a DC .

http://www.ebay.co.uk/itm/1-Channel-Relay-Module-Board-With-Optocoupler-H-L-Level-Triger-30A-5V-12V-24V-/271810754435?pt=LH_DefaultDomain_3&var=&hash=item3f492ef783
 

#12

Joined Nov 30, 2010
18,210
You can't install a mechanical relay rated for (much) less than the full voltage or its coil will overheat quite easily.

I'm thinking about Solid State Relays. They have a wide input voltage range, but I'm only talking about input voltage range because the Thread Starter has said nothing about whether he wants circuit 1 to come on when circuit 2 is barely starting or almost completely on. Next problem: A SSR can be told at what level to come on, but that involves resistors and fingers in the power line circuit. I'm afraid this website forbids that conversation. I will notify a Moderator.

@Ishan Perusinghe
If you're any kind of blue collar circuit board maker, speak up before the Mods lock this thread for being too dangerous.

http://www.mouser.com/Electromechanical/Relays/Solid-State-Relays/Solid-State-Relays-Industrial-Mount/_/N-ay0tw?P=1yvsbasZ1z0z2liZ1z0x39jZ1z0x3t5Z1z0x2pxZ1z0x35lZ1z0x1rsZ1z0x37wZ1z0z812Z1yzsclvZ1z0x15xZ1z0x0n9Z1z0x15vZ1z0x1flZ1z0x37vZ1z0x156Z1yzutolZ1z0x121&Ns=Pricing|0
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
Yeah I'm not looking for anything dangerous . I'm just looking for a simple switch to turn on circuit one when circuit 2 has been turned on . The only difficulty I'm having is circuit 2 has dimmer . Which is making the switching difficult . I don't think anyone has suggested anything dangerous . At what voltage circuit comes on doesn't matter at this point . As long it's above 12 v
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
The led driver in circuit 1 has it own 240v input power as it's wired in Parrell . What Iam looking for is a mechanism to turn this circuit on / off when circuit 2 is on and off .
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
The mechanism to switch on circuit 1 needs a trigger voltage from circuit 2 as long as the trigger voltage is say above 12 v then circuit 1 will come on . If trigger voltages drops below 12 v . Circuit 1 will shut off .
 

MaxHeadRoom

Joined Jul 18, 2013
20,911
As per your post in another site, you have not disclosed all the information necessary to give an accurate opinion, no one is a mind reader here!!.
Max.
 

Thread Starter

Ishan Perusinghe

Joined Jun 24, 2015
19
I have described everything I can . If you have a specific question I will try and give u the Info . But I summary I'm hoping the Ssr will turn on circuit 1 when circuit 2 is turned . Both circuits are in Parrell and have 240 v supply . The only difference is that the circuit 2 has variable pot / switch . That's what I need the keep the circuits separate as u don't want the pot to affect the voltage to the led driver in circuit 1 .
 

dl324

Joined Mar 30, 2015
10,985
I think this ssr with ac-ac will work any thoughts.

http://www.ebay.co.uk/itm/Single-Ph...929?pt=LH_DefaultDomain_3&hash=item3aa1085c91

the amps running through is far less than 20 . so I should be ok .
That relay requires 90-250VAC to turn on.

You should look for an opto SSR that can handle the load for your LED strip (you haven't mentioned load current). You also need to state whether you want to switch both neutral and hot wires or if you only need to switch hot. That will determine if you need DPST or SPST contacts.

Here is an SPST example: http://www.vishay.com/docs/83816/lh1518aa.pdf. It will switch a 240VAC load at 300mA.

With an opto relay, you can put the LED with appropriate current limiting and reverse bias protection in series with your 600W bulb load on circuit 2. When current flows in that circuit, it will trigger the relay and power the circuit 1 load.
 
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