Led for lights

Hi Bros. would like to find out what size of LED that you guys used in your lighting system for head light/spotlight? You guys running it from the same power source for the motor or from another batt source?

Currently building my own light control module so this is right up my ally

I intend to run super bright LEDs for head lights, 5mm, "warm white" with 15000-18000mcd light output. Got some samples last week at Sim Lim Tower - SGD 1.20 for two. Very bright!

I will use the receiver power source (BEC output of the speed controller), and will make a DC-DC converter to 9V and drive the LEDs with a 20ma constant-current source. Basically the same way what the Tamiya TLU-01 does.
Advantage of that method is that the light output stays constant no matter what your battery voltage is.

The simplest method would be to run the LEDs directly off the main battery. For that you would run 2 LEDs in series and add an appropriate resistor to limit the current to 20mA. Note that depending on the LEDs you need a different resistor. Normal LEDs have a forward voltage of ~2V, while high brightness LEDs typically have 3.2V. So with 2 LEDs high brightness, a typical 8V power source (average battery voltage), you need (8V - 2*3.2V) / 20mA = 82 Ohm. For normal LEDs (e.g. normal red ones for the back) you would need 180 Ohm.

If its just for a pair of always-on lights the simplest way is to get a cheap ready-made kit at the local hobby shop though.

Hi. So you are running your lights off a 9V battery (correct me if I'm wrong). Yes I'm looking at installing bright Led light (more than 3-4 pairs). Have done some searching on the web but not quite sure how it work. I would like to have a constance light output. Am thinking of using a separate battery 9V or 4.6V.

Do you have a diagram of how it is being hook up using the BEC method?

Thanks

I will not run a separate battery but rather build a DC-DC converter that converts the 5-6 V that the receiver is powered with (supplied from the ESC) into 9V.

9V is a good compromise for driving LEDs with a constant-current since high brightness LEDs use 3.2V: times 2 that is 6.4V and then you need a bit of overhead for the constant current regulator. With 9V you can perfectly drive 2 high-brightness LEDs or 3 normal LEDs from one constant current source.

A separate battery is a great idea when the lights are in the body shell. This way you don't have to worry about a cable going from the chassis to the body shell that needs to be unplugged every time you take off the body.
I use that method in my TT01 which has the Tamiya light controller TLU-01 installed.

I will make a diagram of how things hook up via BEC later today.
Stay tuned!

Ok, here are some schematics:

First the simple one: driving 2 LEDs from the main battery directly with a simple resistor:


If you want to run more than 2 LEDs then you would wire up pairs of LEDs, each with their own resistor. Simple, solution, but brightness will vary with battery voltage. Also since you are tapping the main battery your wiring needs to be very solid as you don't want to shorten a beefy LiPo


The high-tech solution is to generate a stabilized voltage and drive the LEDs with a constant current. Best performance, but requires expertise in electronics -- or investing in a off-the-shelf light controller like the Tamiya TLU-01.



An excellent description of various LED driving techniques can be found at
http://pcbheaven.com/userpages/LED_driving_and_controlling_methods/

Hi bro. Thanks for the diagram. The link is too deep for me to understand. Just a Noob question, why dun you use 5.6V as the base current instead of 9V (cos you still need to build the Dc to DC convertor)? Since the LED will only draw ~2V and 5.6V will be constant till the battery run to its minimum.

Bros... To save trouble on wiring... Just buy the hobbyking 3.3V BEC...

It can be used with batteries from 2s-6s... It provides a constant 3.3v... Just nice for super bright LEDs from sim lim.... Do note that Whites are 3.3V, Reds are 2V.... Just add a resistor or wire 2 Reds in series and connect to the 3.3v source...

I use the hk BEC on my rigs.. For defender, I use the bec for headlights, driving lights and a r2hobby light unit for the signal lights..

Bro Boolean21, can the BEC work on NiMH7.2V? Not planning on LIPO. Need to save cost by recycling what I have as I plan to get my err... second SCX10... Can I get the BEC locally?

Bro laneboysrc, do you know how to programe a PIC12F683 Chip? What cable is required? Am interested to build a simulated rotating beacon from:
http://diyrc.com/picaxe-miniflash.htm#code

This is how it will look like:
https://www.youtube.com/watch?v=FSMTIlfKY2g

Thanks bros

Yup, no problem for 7.2v.... locally, shd be able to get it at a higher cost...

For the LED running lights, if you just need the lights to run left - right- left -right etc... Like the one in the video, just need to build a simple 8bit counter for 5LEDs...

Then wire the LED 1 - 5 to the counter's output 1-5....
Then LED 4-1 (backwards sequence) to counter's output 6-8....

Not sure if u get what I meant...

very chim... got diagram? and wht parts to buy.

So all bros using normal 5mm LED for the lights? Will go down to Sim Lim soon. So gathering info before going down to get all that I need at one go.

Driving LEDs directly from the 3V3 BEC without resistor will "work" but stressing the LEDs and they may fail (or they may not... electronics are often amazingly tolerant to abuse...)
For a total low-end solution I would rather wire the LEDs with small resister each in parallel and power them from the receiver 5-6V.

Yes, "normal" 5mm LEDs work well for the light buckets and bumpers found in Axial and other kits. Do make sure you go for "High brightness" LEDs.

I do know the PIC microcontrollers, actually have a similar chip sitting right next to me being programmed as light controller for our Dingo
Note that this is a bare microcontroller, so you need to program it with firmware. Plus you need a special programmer board or cable. Unless you are experienced with embedded firmware I highly recommend not going this route. It is a hobby all by itself

no worries... Driving 3.3v LEDs with 3.3v BEC are fine. Some super bright LED are rated 3.6V, some 3.3V, so driving them with a constant 3.3V, they will only draw as much current as they require, I.e. 20mA, so no worries.

Just more risky for the reds, as they are 2V and run in series, so there is a risk that one gets burn out due to uneven draw...

boolean21 wrote:
no worries... Driving 3.3v LEDs with 3.3v BEC are fine. Some super bright LED are rated 3.6V, some 3.3V, so driving them with a constant 3.3V, they will only draw as much current as they require, I.e. 20mA, so no worries.

Just more risky for the reds, as they are 2V and run in series, so there is a risk that one gets burn out due to uneven draw...

Thanks. Will drop by Sim Lim to get my LED and resistors for the red LED.

laneboysrc wrote:

I do know the PIC microcontrollers, actually have a similar chip sitting right next to me being programmed as light controller for our Dingo
Note that this is a bare microcontroller, so you need to program it with firmware. Plus you need a special programmer board or cable. Unless you are experienced with embedded firmware I highly recommend not going this route. It is a hobby all by itself

The site also provides the software to programe the chip. I just want try out. Thanks

Just came back from JetHobby: they have a complete G.T. Power light kit for SGD 19. May be worth considering...

Seems to be this one: http://www.rcmart.com/power-gt0001-light-system-p-27993.html

laneboysrc wrote:Just came back from JetHobby: they have a complete G.T. Power light kit for SGD 19. May be worth considering...

Seems to be this one: http://www.rcmart.com/power-gt0001-light-system-p-27993.html

Thats what i used on some of my RC Cars

im also using that GT power on my rigs.

OK bros. I drop by Jethobby to have a look.