Electrical Gurus. AC/DC LED question

skull, Dec 21, 6:21am
Your step down transformer will convert to DC if you get the right one anyway.

stevo2, Dec 21, 6:22am
I have a few trannys but they all step down in AC. Was hoping to use one.

cammey, Dec 21, 6:28am
LED will run on AC. While they don't really expect to enjoy reverse polarity, they will cope.

It will survive. Just hook it up, as its only working on half the cycle, it will be a bit dimmer than on DC.

A cellphone charger by the way is DC. Easy to buy a DC power supply, just go to jaycar or similar.

gsimpson, Dec 21, 6:34am
or run through a small rectifier or make one up with some diodes.

http://www.sicom.co.nz/bridge-rectifiers-xidg6372.html

medcare, Dec 21, 6:41am
The LED's you linked to are VERY bright, line of sight you can probably see it from a 500m away.

Either run it on lower voltage, say 6-9v or paint over it.

A flashing light on an outside alarm box is not normal, (drive around and see how many you can spot) so putting one outside the house is more like saying " hey thief, look over here, this is a fake alarm"

intrade, Dec 21, 7:08am
transformer has to be for l-e-d. light-emitting-diode
or it be getting hot and melts down like one of my bulbs did before i got a correct led transformer for a few $

clark20, Dec 21, 7:16am
Blue LEDs need around 3.5V, however this fitting is for 12V so the DC 12V transformers are OK

intrade, Dec 21, 7:32am
transformer is inside that light its ultra tini for 8 bux cable in is 240 mains wire
http://www.iforce.co.nz/View.aspx?i=0kzp3nwj.q4b.jpg

donz01, Dec 21, 7:43am
Ask the seller if the led will light up using a 9 volt battery. It says prewired with dropping resistor for 9-14V operation. I have been running 4.2m of 12v led strip lighting for over a year using a 9 volt battery. My leds have gone on and off over 1000 times and they still seem as bright as they did when we first wired them up to a $2 9 volt battery

m16d, Dec 21, 7:43am
This. I'm sure you've got one lying round somewhere.

stevo2, Dec 21, 8:16am
Yeah, got heaps of them but they are only 3 or 4 volts but are DC
Cant find a red or blue pre-wired LED at that voltage, flashing or not.

tony9, Dec 21, 8:46am
LEDs are current sensitive and need a constant current power supply to drive them. Without that they will be unreliable and performance will be unpredictable. Worst case you will get a fire.

Ebay have suitable drivers for low prices, or talk to Jaycar or SICOM.

matarautrader, Dec 21, 10:31am

pauldw, Dec 21, 8:56pm
Isn't a flashing light evidence that the alarm has been triggered but not reset? The siren is supposed to stop after a short period rather than piss everyone off.

m16d, Dec 21, 11:05pm

elect70, Dec 22, 2:14am
Ive put up dummy cameras wit flashing led /sensor . They just take 2 AA batteries & last about 12 months

matarautrader, Dec 22, 5:07am
When I had a security company years ago and had a stand alone double garage about 50 meters from the house I fitted a Micron external siren that flashed about once every 15 seconds when it was armed. Was never burgled with that .

lookoutas, Dec 22, 5:28am
Anyone who's sold you something will have your address.
Best you put up real camera's like I have.

stevo2, May 17, 3:15am
I've got one of those around the back. Batteries last about 1 to 2 months if I use good batteries. 2 weeks if I use cheapies