dummy flashing led

mondeo

Hey,

Anyone know where you can get one of these? Cannot afford a decent alarm right now so want to stick a dummy red led on the dash for the next 3 weeks until I have my cash for my cobra system.
Somewhere use to sell them a couple years ago. I could probably rig somthing
up myself here with abit of DIY but anyways.

Thanking you

crosstownk

Here's a seller with 20 available....

Volvoboy

mondeo wrote: »

Hey,

Anyone know where you can get one of these? Cannot afford a decent alarm right now so want to stick a dummy red led on the dash for the next 3 weeks until I have my cash for my cobra system.
Somewhere use to sell them a couple years ago. I could probably rig somthing
up myself here with abit of DIY but anyways.

Thanking you

The best anti theft system is a chain wrapped around the steering wheel a few times, and chained around the bottom of the seat;)

mondeo

Volvoboy wrote: »

The best anti theft system is a chain wrapped around the steering wheel a few times, and chained around the bottom of the seat;)

I have a 12mm hex motorcycle chain wrapped around the wheel already, I'm confidant enough that the car will still be at the side of the road in the morning but I still like to have a hint of an alarm system. A chain will not keep my stereo in there hehe:rolleyes:

mondeo

crosstownk wrote: »

Here's a seller with 20 available....

Thanks lad, I'm not a fan of ebay though

crosstownk

mondeo wrote: »

A chain will not keep my stereo in there hehe:rolleyes:

Nor will a flashing LED or an alarm. If someone wants the stereo they'll take it. If your that concerned, remove the stereo every night - most are easy enough to remove.

mondeo

crosstownk wrote: »

Nor will a flashing LED or an alarm. If someone wants the stereo they'll take it. If your that concerned, remove the stereo every night - most are easy enough to remove.

Your probably right dude....

Maplins in the UK sell these dummy units, I wonder will maplins in ireland sell them also? I'll give them a ching in the morning and find out..

http://www.maplin.co.uk/Module.aspx?ModuleNo=30379&doy=12m9&C=SO&U=strat15

DublinDilbert

Maplin will do the dummy flashing 12V LED's for a couple of Euro. Lots of car shops do them too.

The best way to connect them is to connect the + connection to a permanent 12V supply, and the - connection to a circuit which is switched to 12V when you turn the key on. This means the LED will flash only when the key is out of the ignition.

colm_mcm

DublinDilbert wrote: »

The best way to connect them is to connect the + connection to a permanent 12V supply, and the - connection to a circuit which is switched to 12V when you turn the key on. This means the LED will flash only when the key is out of the ignition.

this looks wrong to me.

eringobragh

Where are u based OP?? If your in North Dublin I've a couple of spare green or blue flashing LEDs wired that i intended on replacing my red one with.

Max_Damage

I got one for my car in Halfords.

mondeo

eringobragh wrote: »

Where are u based OP?? If your in North Dublin I've a couple of spare green or blue flashing LEDs wired that i intended on replacing my red one with.

I'm living in portlaoise, won't be in dublin until tuesday though

eringobragh

mondeo wrote: »

I'm living in portlaoise, won't be in dublin until tuesday though

Drop me a PM before Tuesday if yout still stuck.

DublinDilbert

colm_mcm wrote: »

this looks wrong to me.

I've a masters degree in electronic engineering and have been designing automotive electronics for the past 8 years. I know how to wire up a 12V LED and back feed it through a circuit so it just turns on when the ignition is switched off

crosstownk

DublinDilbert wrote: »

The best way to connect them is to connect the + connection to a permanent 12V supply, and the - connection to a circuit which is switched to 12V when you turn the key on. This means the LED will flash only when the key is out of the ignition.

I'll agree with colm. It doesn't make sense.

+12VDC - permanent - to the battery; then connect the negative to the battery (+) when the ignition is turned on? What? Both would then be connected to the +12VDC, no?

eringobragh

He half explained it you MAY need a resistor also.

Handy Guide:

http://www.nifty-stuff.com/car-alarm.php


.

DublinDilbert

crosstownk wrote: »

I'll agree with colm. It doesn't make sense.

+12VDC - permanent - to the battery; then connect the negative to the battery when the ignition is turned on? What? Both would then be connected to the +12VDC, no?

exactly!!! so when the ignition is on both sides of the LED are connected to 12V! hence the LED is off and will not annoy you when driving.

But when you turn the ignition off, one side of the LED will be at 12V, the other side of the LED will be sitting at near ground, hence your LED will spring to life

crosstownk

DublinDilbert wrote: »

exactly!!! so when the ignition is on both sides of the LED are connected to 12V!

Do you mean that both sides are connected to +12VDC? If that is the case then there will be no potential difference.....

DublinDilbert

crosstownk wrote: »

Do you mean that both sides are connected to +12VDC? If that is the case then there will be no potential difference.....

Yes, there will be no potential difference, hence the LED will be off when the ignition is on.

But when the ignition is turned off there is a potential difference.

colm_mcm

so are you in a way connecting a permanent live to the accessory live? this won't cause any problems?

DublinDilbert

colm_mcm wrote: »

so are you in a way connecting a permanent live to the accessory live? this won't cause any problems?

Nope cause the LED will only allow a few micro amps to flow between the two.

The LED is a very high resistance, it will never be able to put the switched 12V more than a few mV above ground.

colm_mcm

Cool. good to know.

DublinDilbert

colm_mcm wrote: »

Cool. good to know.

Its handy, cause that LED flashing would drive you mad when driving at night time, if it was on all the time...

bazz26

I bought one of these in a motor factors about 12 years ago. You plugged it staright into the cigarette lighter and the led flashed.

Embarrassing, looking back at it now.

colm_mcm

Anyone remember an album called "Pulse" by Pink Floyd, released in the mid 90's
Had a red LED that flashed like a heartbeat. Thought it was the coolest thing ever at the time!