DIY LED brake lights. Need help.

[me2kimi]

Sifu levin818, what is your opinion about 555 led driver? Is it ok or not to use 555 as led driver for the brake light. As far as I know, 555 also can make dimmer for the led.

Here is example of what I'm talking about.
http://www.pcbheaven.com/circuitpages/LED_PWM_Dimmer/

 

[stupidcar]

Sifu levin818, what is your opinion about 555 led driver? Is it ok or not to use 555 as led driver for the brake light. As far as I know, 555 also can make dimmer for the led.

Here is example of what I'm talking about.
An LED Array PWM Dimmer with the 555

Damn, u guys are damn good.

Btw, my lower of the 2 led row keep failing. Strangely is only by one resistor at a time.
The upper one is good, maybe it's because it's only on all the time if turned on.
The 2nd row is when the brake is applied. :\

If I put another 10ohm++ resistor on the main ower source, will it be okay?
So my 100ohm resistor for my 4 leds should be with 110ohm, can it be counted like that?

 

[me2kimi]

I think you should change to hi watt resistor type.

Sent from my Galaxy Nexus

 

[levin818]

Sifu levin818, what is your opinion about 555 led driver? Is it ok or not to use 555 as led driver for the brake light. As far as I know, 555 also can make dimmer for the led.

Here is example of what I'm talking about.
An LED Array PWM Dimmer with the 555

Hi me2kimi, yes it can be use but will become a bit complicated if you want to make it control by brake signal.

---------- Post added at 10:56 AM ---------- 6 hour anti-bump limit - Previous post was at 09:42 AM ----------

Damn, u guys are damn good.

Btw, my lower of the 2 led row keep failing. Strangely is only by one resistor at a time.
The upper one is good, maybe it's because it's only on all the time if turned on.
The 2nd row is when the brake is applied. :\

If I put another 10ohm++ resistor on the main ower source, will it be okay?
So my 100ohm resistor for my 4 leds should be with 110ohm, can it be counted like that?

It mean you LED current is actually more than 50mA, and your actual LED voltage is about 2.1V @ 50mA. This is the 20mA LED's characteristic. You need to down tune your current to 20mA~30mA otherwise the LED will die in within a year, especially those that function as tail light.

Suggest you add a resistor 47R~62R 1/2W in series at the main source. Tail light one piece, brake light another piece.

 

[stupidcar]

Hi me2kimi, yes it can be use but will become a bit complicated if you want to make it control by brake signal.

---------- Post added at 10:56 AM ---------- 6 hour anti-bump limit - Previous post was at 09:42 AM ----------



It mean you LED current is actually more than 50mA, and your actual LED voltage is about 2.1V @ 50mA. This is the 20mA LED's characteristic. You need to down tune your current to 20mA~30mA otherwise the LED will die in within a year, especially those that function as tail light.

Suggest you add a resistor 47R~62R 1/2W in series at the main source. Tail light one piece, brake light another piece.

Yes, the brake function current is higher.
Hmm, now I understand. But then when I ran the wizard I typed in 20mA too.
Know what to do dy.

 

[levin818]

Yes, the brake function current is higher.
Hmm, now I understand. But then when I ran the wizard I typed in 20mA too.
Know what to do dy.

Because your key in LED voltage at 2.8V.
You suppose to key in only 1.9V.

 

[stupidcar]

Because your key in LED voltage at 2.8V.
You suppose to key in only 1.9V.

I don't understand.

 

[levin818]

Mean you input a wrong figure of Vf into the wizard, so it calculate and gave you wrong resistance value.

 

[stupidcar]

Mean you input a wrong figure of Vf into the wizard, so it calculate and gave you wrong resistance value.

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

 

[me2kimi]

I think Vf=forward voltage

Sent from my Galaxy Nexus

 

[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?