Backyard Aquaponics
A place to discuss aquaponics

I was thinking of this while I had lunch, and I think a 12v version should be easy to make. This has a couple of advantages, the main one being there in no 240v power being played with and the second is price.

As I have it in my head at the moment, I will use a 12v plugpack (aka wallwart) and then use this to trigger the relay. I think I will also need a normally open (NO) relay rather than a NC one like I said earlier. The plugpack will run the relay, holding it open, so that if the power fails, the relay closes and the battery operated 12v pump kicks in. When the power returns, the relay will open again, switching off the pump. Only need to add a trickle charger to keep the battery charged.

The only problem is switching the pump off before the battery goes completely flat (or buy a deep cycle battery).

Murray, how does your gadget work? Similarly to what I described? It sounds interesting.

Nova

The 240 volt holds the relay open , when the 240 volt dies the relay closes sending the 12 volt from battery to small bilge pump that pumps a waterfall onto the surface of the tank. Yes the size of the battery is important. I do not see the gadget doing anything except to hold the system for an hour or two anyway, as a safety device if power went out due to a storm or a car hitting a power pole etc., during the night or while you are at work.
If there was a long term power outage due to a cyclone or similar that would have the power out for a day or more then you would only expect this device to aerate the fish tank until one could get a 240 volt gen set into place. To run a small 12 volt bilge pump, say 500 gph, a battery costing around 100.00 would run such a pump for 5 or 6 hours, more battery = more running time.

I will price the gadget tonight and put a photo up on the forum for those who are interested.

Muzza

Nova and all,

Just buy an industrial "contactor" i think they are about $20 - $30 and have interchangable "coils" meaning that you can make it a 24V drive or 240V drive, what ever turns you on and makes you feel safe. They are 3 phase in that they have 3 seperate switched contacts, i think each are capable of carrying 32A. Generally they are NO contacts (you need NC) but you can buy various "snap on" terminals that will accomodate any variation you need. Any electrical wholesaler will have one of these.

The one pictured has 3x main NO contacts, with 2x auxillary NC and 2x auxillary NO contacts as standard.

Ask for any questions or diagrams, as ill be back on later, but for now, i'm tired and have a headache have had a long day, half of it spent with only one contact lense in

that's not too good to hear - go and look after yourself mate

No idea what you are talking about Steve. I am retarded when it comes to these types of things. When other kids in primary school were putting together Tandy electronics kits, I was brewing my own cider in my bedroom cupboard (never threw an apple in the bin) and making my own alcohol still.

Steve - Remote reiki on its way.
Threads of gold and silver.
Healing green light.

HAHA, who's laughing now? (well, both of us, you can get pissed for free!)

and you can tell me what the f you are talking about in that earlier thread. Does this substitute for a power fail switch and what exactly do you need to do to turn it into one (including housing it)?

GF- Good basic ingredient for grog though.

me too please, can you give us a quick run down in English LOL

OK, I'm going to spell it out so nothing is assumed, so dont think i'm "talking down"

A relay: A device that contains a coil of wire around a soft iron core and a set of contacts. When power is applied to the coil (Voltage is dependant on design) the soft iron core becomes magnetized, and pulls the contacts in to bridge them.

The contacts in the above description are called NO (normally open) becasue, well, they are normally open when there is no power to the relay. These are the most commonly used contacts. Relyas are generally used to switch heavy current loads that would normally burn out a switch.

For example if you ran your starter motor trough your ignition barrel contacts you might get your car started before your steering column caught fire....maybe. But the way it is done is that the small contacts that are closed when you turn your key supplys power to the COIL of the relay (not much power needed here.) The relay energises (Normally open contacts close) and supplys circa 300 amps to the starter motor.

(The relay in the starter motor is actually housed INSIDE the starter motor assembly, but its still a relay no less.)

OK, so now you know what a relay is and does, and how it works.

Normally CLOSED contacts are ones that are "bridged" when there is no power to the relay. Forming a picture? When power is applied to a relay it pulls the N.O. contacts together..........by virtue of this happening the N.C. cotacts are pulled open.

N.O. = Normally open = they form a circuit when when power is applied to the relay

N.C. = Normally closed = They break a circuit when power is applied to the relay.

Contactors are just BAD ASS relays, like monster trucks to minis

AS mentioned they have interchangeable coils (the voltage required to activate them) So within 1 minute you can change a contactor that is "activated from the output of a battery charger or car batery, to one that is activated directly from the wall socket. (I know there are 240V and 24V coils available, just gotta check on the 12V)

SO,

A power fail relay is nothing more than a N.C. (you all know what that stands for now) contact on a relay!

For example: power straight from a 3 pin plug is wired to the coil terminals of the relay. A 9 volt battery (same as in a smoke alarm) is wired through the N.C. contacts of the same relay and to one of those ear pearcing buzzer you can buy. Thast it, job done. whack it all into a $2 box.
When you plug it in, the relay will activate and break the buzzer circuit. When your power goes out (or you unplug it ) the relay will deactivate, which menas the N.C. contacts will complete the buzzer circuit, and you have audible warning of a power outage.

You could substitute the 9V battery and buzzer for a car battery and a 12V pump. WHen the power goes out the battery becomes connected to the pump and hey-presto you have automatic back up bubbles

The circuit can be made more advanced from here to contain auto charging for the battery and so on an so forth, but thats beyond the scope of this post (I've ALWAYS wanted to use that line!)

Any questions?

Thanks Steve. Funny how when I rang Jaycar and Dick Smiths today, neither had any idea how you would do it. I still can't say I would be able to set one of these up, but at least I have a bit of a grip now.

Fools that they are, almost every relay you buy from dickies or jaycar has both NO and NC contacts

The guy at Dicks said "I'm sure we would have the bits, but you would need an exact list, none of us have got a clue"

That's what happens when Woolies owns everything - or is it Coles that owns Dick Smith and Tandy?