Mains relay help please :D

[6L6]

Hello all!

I have a chassis that I salvaged, it's quite nice, and it has a small front-mounted power switch and LED. It was originally for a relay on a 100W SMPS or something of that ilk.

Anyway, what I would like to do is use the small momentary switch to trigger a relay on the primary side of the mains transformer.

I have no idea where to start, and there may be a very simple answer to this, I am just ignorant of it -- I have only ever used big beefy switches on the mains.

Any info, part numbers, links, etc.. will be very welcome!

[imix500]

I am using a tiny little board from Sparkfun to control an SSR from a momentary pushbutton in the F5T I'm building. Maybe worth checking out the board.

[6L6]

Do you have a produce name or a link?

I looked at the Sparkfun website, but nothing is jumping out at me...

[imix500]

Sure,
There are two versions. Here's one.

Pushbutton Power Switch LV - SparkFun Electronics

The only cavat with it is the switch terminals cannot be tied to the supply terminals i.e. a three terminal illuminated switch.

[6L6]

So one of those would be used to control the coil on a relay? Is that the basic idea?

[AndrewT]

Use a latching relay in the primary circuit.
There are various ways to implement latching using an ordinary non-latching relay.
Some use one or two extra low current, low voltage relays to control the main Power high voltage relay to allow for latching and unlatching using a momentary Make switch controlling a low voltage current.

[imix500]

Yup, the board turns a momentary switch into a latching output to drive your choice of relay. It also has some de-bouncing built in and has a garunteed output state on power up.

Andrewt's method works well too. I have also done it with more relays.

[6L6]

Andrew - I understand what you are saying, but if you have any schematic or links to the general idea (or specifics) of what you are talking about it would be greatly appreciated.

imix - So the sparkfun module turns into a 'latch' for a standard relay. Momentary switch -->sparkfun board --> relay coil. Right? Do you have any examples of what would be a suitable relay?

[imix500]

Yes, it's the same as building a simple two transistor latching circuit or using a couple relays, except this is already done in a tiny little board that seems well suited to the purpose of using a momentary switch to act like a push-on, push-off switch.

The two versions are two ranges of operating voltages. The supply voltage is the output voltage.
I am driving a 30 amp SSR with 12v and it works great at such a low current, but it will switch unto 10A according to the data sheet. So, it should be able to drive most mechanical relays as well.

[AndrewT]

Momentary Switch
On/Off Switch

This last could be done with low voltage and the output could then drive a mains relay.
On/Off Switch