DIY LED brake lights. Need help.

[goohtj]

Vf is? Google don't have. Walao..

connect a ammeter to measure the current.

 

[artful]

Hi levin818,

I was thinking to use 18LED which in 3led x 6bank in order to make easier for wiring for tail n brake light function. From the below diagram highlighted in red, which resistor should i use for 3led x 6bank??

From your LED's V-I curve:
When I = 50mA, Vf = 2.45V
When I = 30mA, Vf = 2.26V

[Brake Light] (+) -- 7809 -- diode ---------┐
[Tail Light] ...(+) -- 7809 -- diode -- 6R2 --•-- 22R -- LED -- LED -- LED ---•-- (-)
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘

Diode = 1N4007, all resistor @ 1/4W 1% tolerance

And another question is how to connect Voltage Regulator IC 7809?? It come with 3pin

[Brake Light]---->(Vol IN)7809(Vol Out)---->diode
(GRD)??? where to connect this?? It is connect to the negative??

Thanks

 

[levin818]

Hi artful, please see the following:

At I = 50mA, Vf = 2.45V
At I = 30mA, Vf = 2.26V

[Brake Light] (+) -- 7809 -- diode ---------┐
[Tail Light] ...(+) -- 7809 -- diode -- 5R6 --•-- 22R -- LED -- LED -- LED ---•-- (-)
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘

Diode = 1N4007, all resistor @ 1/4W 1% tolerance

For voltage regulator:
[Brake Light]---->(Vol IN)7809(Vol Out)---->diode
Connect GRD (center pin) to negative.

---------- Post added at 01:33 AM ---------- 6 hour anti-bump limit - Previous post was at 01:16 AM ----------

After you wire up everything, and when first power on, use a volt meter to make a quick measure the voltage drop across one of the 22R resistor.
At Tail Light function, you should have 0.6V~0.7V (27mA~32mA)
At Brake Light function, you should have 1.0V~1.1V (45mA~50mA)

If the reading is far beyond the range, you might want to disconnect the power immediate and re do the calculation.

 

[shiroitenshi]

like i previously told him.. car always calculate using 14.5. now i know got simple linear voltage regulator, makes it even easier, no need to bother with 11v-14.5 v difference when engine running or not.

Sent from my GT-I9100G using Tapatalk 2

 

[stupidcar]

Hi artful, please see the following:

At I = 50mA, Vf = 2.45V
At I = 30mA, Vf = 2.26V

[Brake Light] (+) -- 7809 -- diode ---------┐
[Tail Light] ...(+) -- 7809 -- diode -- 5R6 --•-- 22R -- LED -- LED -- LED ---•-- (-)
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘
.................................................. ..........└-- 22R -- LED -- LED -- LED --┘

Diode = 1N4007, all resistor @ 1/4W 1% tolerance

For voltage regulator:
[Brake Light]---->(Vol IN)7809(Vol Out)---->diode
Connect GRD (center pin) to negative.

---------- Post added at 01:33 AM ---------- 6 hour anti-bump limit - Previous post was at 01:16 AM ----------

After you wire up everything, and when first power on, use a volt meter to make a quick measure the voltage drop across one of the 22R resistor.
At Tail Light function, you should have 0.6V~0.7V (27mA~32mA)
At Brake Light function, you should have 1.0V~1.1V (45mA~50mA)

If the reading is far beyond the range, you might want to disconnect the power immediate and re do the calculation.

May I ask what is 5R6?

 

[levin818]

5R6 = 5.6 ohm
22R = 22 ohm