electrical problem..

[bigpoppa88]

ok, I just had my stereo stolen from my beloved '88. So before I replace it, I am too cheap to put in an alarm system. Therefore to make a simulated one, I put in a blinking LED, an on/off switch under the dash. To power it I was going to tap into the constant power at the cigarette lighter. PROBLEM...as soon as I ground it (with the switch "on"), I blow a 15 amp fuse. What's up, I am electrically ignorant....please shed some light on this! In the meantime I'm just running it off of a 9 volt battery.

[dosh8er]

ok.. so let me get this straight... you've got an LED that BLINKS and you're wiring it into the cig. lighter's 12vdc and grounding it out with a switch (to turn it off when you drive, i presume).

Ok, mr. electronics is going to say a few words..

WHat is the voltage/ampre rating on the back of the package your LED came in? (IF it's radio crack lemme have the number, I might know what LED you're talking about)

Normally, LED's (esp. these blinking ones) don't run on 12 vdc. Instead they like something between 3-9 (9 at max!).. But this all depends on the rating on the back of the package. Did you check your LED after you hooked it up to the 12vdc? I bet it won't work if it's not rated for 12vdc.

Make sure you have wired the switch properly. It's one of those rocker switches? (Like the ones most car alarms have... a light switch style, up/down)

You should wire it like this:

http://milokp.dyndns.org/~dosh8er/honda/switch.gif


THE last thing that is VERY important with LED's is the fact that they have POLARITY (A big word meaning pos. and neg. MATTER A LOT!).

Here's how ANY LED should be properly wired into a circuit:

http://milokp.dyndns.org/~dosh8er/images/led.gif

Make sure the small part inside the LED is the lead that goes to the POSITIVE, and the larger part inside the LED is the lead that goes to the NEGATIVE. VERY IMPORTANT.

[bigpoppa88]

Thank you electrical god!!! That's a lot of info! Let's see, the led i bought from an electronics place froma bulk bin so it had no spec's on it (I told the clerck what I was doing and he just went and handed me one). The switch is NOT a rocker type but a push button type, with only one terminal hook upi for each side , not 4 like the picture you posted. I'll go and purchase the types you recommended...thanks dosher8!

[DanG86LX]

OMG.. to blow a 15A fuse with a LED which require ~20mA (1000 times less).. i guess something's fishy.. either ur LED or ur switch might be shut!
Make sure u tie them in series:
CL+(12V) to SW1 ; SW2 to LED+ ; LED- to CL-(GND)
where: CL = Cigarette Lighter
SW1,2 = switch terminals 1,2
U may also insert a 300ohms resistor in series cuz those blinking LED are for 5V.
CL+(12V) to SW1 ; SW2 to 300ohms ; 300ohms to LED+ ; LED- to CL-(GND)

[bigpoppa88]

Dan hit it on the head! As soon as I saw you post "series" it clicked. I had the ground coming back to the switch instead of straight to ground . Thanks guys!!!!