ok i give in where do i find a 12v ac relay?

[pcorpe]

Can you help me solve this one?

I have an existing doorbell with 2 ringers (3 storey house), that is mains powered (12v ac transformer)

i want to add a second ringer, only i want it to be wireless for in the garden, so i've got a wireless push and cordless ringer, and disassembled the push, soldering on 2 wires either side of the switch.

in a vague attempt to get something to work i tried a 12v dc relay, which kinda works (makes a light flicker), however the relay switch isn't long enough to mimic the doorbell push.

so any ideas? suggestions?

 

[RF Lighting]

Are you handy with a soldering iron? You could make a little rectifier out of some diodes so the DC relay will operate on AC

 

[Fuseblower]

Your half way there already.
Try this....
Feed the relay coil via a small bridge rectifier..
Across the coil connect a suitable capacitor (about 100mfd) that will hold the relay on for half a second or so to allow the wireless system to work.

sounds more complicated than it is but It's all I can think of.

Regards FB

 

[securespark]

http://www.willow.co.uk/

Fantastic! I've had three relays off them & they are still working reliably several years down the line...

 

[breezer]

maplin

OR you could get a 4001 diode and put it in series with the rlay you have (maplin sell those too)

 

[Taylortwocities]

I reckon one diode in series and a cap across the relay would be the minimum for a dc relay . Doesnt really need a full wave rectifier.

 

[Lectrician]

Or just get an AC relay


Even my wholesaler stocks them - The type that plugs into a din-rail mount base....

 

[ebee]

If memory serves correct I do remember 12V AC were not common at electrical wholesalers but electronics ones gen stocked them.
If you do use the DC one with diodes(s) you will either get a reduced or higher DC voltage, if higher and it`s past the coil spec voltage then calculating a series resistor should protect the coil, a cap accross the coil will help smooth the voltage too

 

[breezer]

with just one diode the differeance is neither here or there.

with 4 diodes (bridge rectifier) the voltage drops slightly. if you then put a smooothing capacitor on it the voltage is multiplied by around 1.5 times.

put 1 diode on it will be the best option

the octal base relays are not good idea in this case, they tend to draw a lot of current (for what they are) which most door bell transformers can not supply.

 

[pcorpe]

Gents, many many thanks, there's a wealth of knowledge far greater than my own!.

I'm very happy with a soldering iron, however i confess talk of capacitors, rectifiers and the like sounds complicated to me, i've been searching high and low for a suitable ac relay, which is what led me to post here, an ac relay would be my favoured solution as i think i can suss that out.

so on the basis that i can't find an ac relay it seems diodes and a cap are required, so for the pure layman, does anyone feel inclined to give me a detailed shopping list and perhaps a diagram?

Many thanks

Pete

 

[breezer]

IN4001 diode in series with the relay you have. done cost 12p

see the link i posted earlier

(maplin part number QL73Q)

 

[RF Lighting]

 

[ban-all-sheds]

so on the basis that i can't find an ac relay

Errr....

http://www.willow.co.uk/

 

[pcorpe]

Folks thank to one and all, the diodes as a bridge rectifier thingy did the trick, chuffed to bits, thanks again


regards
Pete

 

[roberta1000]

You don't even need the relay. I've had a setup similar to this for several years. Short out the switch on the wireless pushbutton and feed its power supply from the voltage across the mains-powered bell via a diode, resistor, zener and capacitor. No relay needed and no battery to go flat in the wireless sender.