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Fishing LED

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aaron_515

New Member
Hello everyone, i am new to this forum and need a little help please.

I am basically trying to make an LED bite indicator that will connect to the bottom of my alarm. when the alarm sounds, the LED lights up. The connection at the bottom of my alarm is a 2.5 mm DV out jack (i think) and is actually there for the purpose of an indicator with LED but these cost 30pounds each.
if anyone could offer some advice on the components i need and how to go about this project then i would greatly appreciate it.

Regards,
Aaron
 

Sceadwian

Banned
Got a multimeter? Find out what the voltage comoing out of that port is when the alarm goes off.
 

aaron_515

New Member
thanks for your quick reply, i do not have one but might be able to get hold of one.
is it a big problem if i dont have access to one?
(i dont no too much about electronics lol).
 

colin55

Well-Known Member
Just put a LED and 470R in series and connect them to the output. If the LED does not light up, reverse the LED.
 

aaron_515

New Member
how do i go about connecting the LED to a 2.5 mm jack?
also, what is the resistor for? (i am guessing this is what you meant by 470R).
thank you for your help.
 

Sceadwian

Banned
It's probably just a simple power connector to the LED module that lights the LED's when it's active. It should be pretty simple to wire an LED to it, but we need to know the voltage so we can tell you how many of each LED's you need in series (if any) and what resistor you need to use. You can buy a meter at radio shack for about 20 bucks. I bought a cheap ultra basic Chinese nockoff online for 5 bucks.
 

Sceadwian

Banned
Colin, using a generic 470 ohm resistor is for a 12 volt supply, considering the device is battery powered I doubt it's 12 volts so the brightness of the LED will be lower than if he chose a resistor for the voltage out.

Please do NOT post circuit suggestions when you have NO clue what the posters requirements or needs actually are, it does more harm than good. If you don't know what his voltage are at least put a caveat in your post so that he knows you're just guessing.
 

Sceadwian

Banned
aaron how many batteries (and what type) does your fishing alarm use? That's likely the supply voltage they're getting so you might not need a meter. LED's are diodes, so once they get the voltage they need to operate they'll draw fantastic currents if they're able to, the resistor will drop the voltage the LED doesn't need and keep it from frying.
 
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aaron_515

New Member
it runs off a 9 v (square) battery.
sorry if i have not made this clear but will try again, i want to connect the led to the jack plug so i can plug it in when its needed (ie at night).
once again thank you all for your replies
 

Sceadwian

Banned
What LED's do you want to use?
 

aaron_515

New Member
the ones that i want need to be a maximum of 3mm wide so that they will fit where i need them.
i have found some from a supplier with lots of different specs but i am unsure what i need. the brighter the better but i dont want it draining the battery.
sorry if that doesnt help, i really dont no much about this lol.
thanks again
 

Sceadwian

Banned
If the Alarm circuit makes the LED's flash on that connector you're fine it won't use too much current. With LED's you only need to know two things, It's forward voltage, and it's rated current. The exact specifications don't matter too much you just need to know what they are. Also you need 'wide angle' LED's they're less like spotlights more like beacons. For a single LED you can use a 470ohm or close resistor in series as colin suggested, for the real device I would recommend two bright white LED's in series and a smaller resistor like 100ohms. If your Alarm output only sends a fixed voltage when it triggers and relys on the LED module to blink the LED's you'll need to use blinking LED's instead for simplicity. Solid on LED's won't make you notice them very well.

Sorry if that's a bit much to take in, ask about any questions you still have.
 
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Sceadwian

Banned
You have a 9 volt power supply. So that's your start.

Say your LED drops 3.1V forward, and has a current limit of 20ma (typical for a bright white LED)

Subtract that 3.1 volts from your initial 9V supply. 5.9 in this particular theoretical case.

You use the equation R=V/I to find out the resistor you need. 5.9 /.02 Which works out to about 300ohms.

If you noticed the 9 volts is divisible more than once by 3.1, so you could use two LED's in series, for a total voltage drop of 6.1. Do the math again for the same 20ma (.02 amps) and you should come up with 140 ohms of resistance.

Please note V is WHOLE volts, R is WHOLE ohms, and I is WHOLE amps of current (1 MA is .001 AMPS)
 

Sceadwian

Banned
If your LED's are steady on when you assemble your makeshift LED's make sure you send a post back here, a 555 should easily be able to blink them. I didn't mention it because you wanted simple, and we have no way of knowing if that output port is already flashed by the alarm circuit on the buoy. You'll find out when you hook up real LED's.
 
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aaron_515

New Member
yes i will do, i think it should be because the purpose of this jack socket in the alarm is for this very purpose but if i have any trouble i will ask.
thanks again:)
 
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