Smart Car DRL Controller

The post explains how the DRLs in a car may be controlled by reducing its intensity while the headlamps or the indicator lamps are being used, for enhancing its efficiency. The idea was requested by Mr. Rob. Let's learn more about this smart DRL intensity manager circuit.

Technical Specifications


Hi Swag,

I'll try and explain in more detail. I want a module which will connect to a set of aftermarket DRLs that will allow them to turn on when the cars ignition is on (ideally via direct battery connection with a voltage sensor to turn them on but if not via ignition live feed).

The module needs to connect to the headlight so that when it is turned on the DRLs dim to 50%.

The module also needs to dim the DRLs when the indicator is activated on that particular side of the car (right DRL dims when right indicator is turned on etc.).

This aspect isn't necessary when the headlights are on as the DRLs are already dim. When the indicators turn off I would like the DRL to fade back to full brightness say over a period of 2 seconds or similar.

It is basically just like the new Audi DRLs which are built into their headlights.

I hope this is enough information for you to produce a schematic but if not I can try and give you some more information. Also, using your relay method would be best!

Thanks

Rob

The Circuit Design


The proposed smart, energy efficient DRL controller circuit could be constructed in any of the following methods.

The first one is a rather crude approach which will provide the intended results but will not save any electricity for you, so the purpose could fail here.

The T1 stage is included for enabling the fade-back effect over the DRL, if this feature is not required, T1, R2, C1 may be entirely eliminated and the N/C of the relay directly joined with the junction of DRL positive and R1.

C1 decides the gradual brightening period of the DRL

The second design could be considered energy efficient due to the inclusion of a voltage regulator stage incorporating T2, R1, R2. T2 is configured as a common collector.

Here T1 and the associated parts perform the same function as above while T2 is rigged to produce 50% less voltage for the DrL when the headlights or the turn signals are switched ON.

The last circuit is also a smart way of controlling the DRL illumination.

Here the T2 stage has been replaced with the LM317 current regulator stage which controls the DRL intensity by 50% during the recommended situations but unlike the second circuit it executes the operations by reducing the current instead of voltage.

 Circuit Diagram




Parts List for the above circuit designs


R1, R2, R3 = 10k

T1, T2 = TIP122

D1, D2 = 1N4007

D3 = also 1N4007 (optional)

Relay = 12V, 400 ohms, SPDT


Parts List for the above circuit design


R1 = 1.25/DRL amp value (less 50%

R2 = 10k 1/4 watt

C1 = 470uF/25V

T1 = TIP122

D1, D2 = 1N4007

D3 = also 1N4007 (optional)

Relay = 12V, 400 ohms, SPDT

Feedback, and suggested corrections from Mr. Rob

Hi Swag,

Thanks for doing the schematic of the DRL Indicator module. The reason we need it to dim is to make it legal in the UK to have DRLs and Indicators so close to each other.Anyway, I've ordered the parts for the schematic as I'm short on a few bits however just a query with the 12v + supply to the battery.

As the battery is constantly live will this 'module' be constantly draining power when the car is not in use as the DRLs would always be on? If it were a 'ignition live' positive feed then this would only provide power to the 'module' when the ignition is turned on.

What are your thoughts on this? Do we need to look at installing another circuit which goes to the battery that has a separate trigger switch that can identify when the car is not being used/ignition off?

Thanks again
Rob

Analyzing the Feedback Query


Hi Rob,

You are right, the +12V needs to come from the ignition feed, meaning only when the ignition is switched ON, the DRL and the associated circuitry should be triggered ON for the required operations.So the modification will be simple, instead of connecting the +12V to the battery we can integrate it with the ignition 12V feed.

The above smart DRL circuits could be also used for high watt DRL applications, an example 50 watt modification is illustrated below:

The 12V, 20 watt series lamp could be hidden somewhere under the bonnet, it's included for dipping the DRL illumination to approximately 50% less.



Upgrading DRL to a Solid State Version

The above designs can be upgraded to solid state versions by completely eliminating the relay, and  repalcing it with an inexpensive BJT stage as shown below, the idea was requested by Mr. Dhar Vader


Parts List for the above Solid State Automatic DRL circuit:


R1, R2, R3 = 1K, 1watt.

R4, R5 = 10k, 1/4 watt

T1, T2 = TIP122

T3 = BC547,

C1 = 470uF/25V

D1, D2 = 1N5408

Need Help? Please send your queries through Comments for quick replies! And please Bookmark my site :)




Comments

Rashid Ansari said…
Hello Sir,

Greetings.

Sir, I have a small business of rent a car and have to put a tracker on vehicles but tracker companies are very expensive here. Is there any way to track the location of the vehicles within the city by using my cell phone. Hope u will be able to help me in this regard.

Thank you.
Rashid Ansari
Swagatam said…
Hello Rashid,

you'll require a GPRS installed in the vehicle, I don't think there's a cheaper alternative for this.

If you can crack how to track IMEI numbers then probably you can do it by inserting a working cell phone somewhere in the vehice
Rob Admin said…
Hi Swags, I've ordered the parts for the above however just a query with the 12v + supply to the battery. As the battery is constantly live will this 'module' be constantly draining power when the car is not in use as the DRLs would always be on, i.e. if it were a 'ignition live' positive feed then this would only provide power to the 'module' when the ignition is turned on.
What are your thoughts on this?
Swagatam said…
Hi Rob, you are very much correct, let the +12V supply come through the ignition feed, this will solve the issue for us.
Swagatam said…
if suppose at full illumination DRL amp consumption is say 300mA, then 50% of this would be 150mA (0.15 amps)...this value must be used in the formula

R = 1.25/0.15 = 8.33 ohms
Swagatam said…
Hi, yes it will work, it's perfect.
Swagatam said…
you can connect the two DRLs in parallel at the shown position of the last circuit.

the ground of the DRLs may be separately terminated via the collectors of T1, T2 in this circuit, meaning the DRL ground wire should be connected to the junction of RC1/RC2 and T1/T2 respectively
www.scrigroup.com/files/electronica-electricitate/890_poze/image001.png

Use 2N2222 or 8050 for T1 T2, since the DRL current is not too big would be easily handled by these transistors.

I think discussing in an open forum could enlighten other guys also, so its better to solve it out here:)
Swagatam said…
...correction: the DRL ground wire should be connected to the junction of RC1/T1 and RC2/T2 respectively
Swagatam said…
with 6nos 1 watt leds (3 on each channel) you would need to change the 1 ohm resistor to 10 ohm 1 watt.....that's all
Swagatam said…
note that the IC will need a heatsink, a small 2 x 2 inch, 1mm thiick aluminum metal could be glued over the 555 IC surface for optimal performance.
Swagatam said…
Hi, I have explained the configuration with greater details in the following article, you can refer to it here:

https://homemade-circuits.com/2014/06/upgrading-car-parklights-into-enhanced.html
Swagatam said…
No you won't need any driver, because the circuits are able to handle up to 16V, the LM317 shown in the above article is positioned for dimming the DRL illumination to 50%.... not for protecting the DRL.
Andras Vincze said…
Hi Swagatam,

How would you need to change the schematic if your DRL module is a high power (50W) Cree LED? I basically want to keep the functionality that is two stages: 100% and dimmed 50% when park light or turn-light is switched on.

Thanks
Swagatam said…
D4 and R3 is for producing a slow delay ON illumination on the DRL (slow rise effect), if its removed the DRL will come ON at once.
Swagatam said…
Hi Andras,

I have updated the required design at the end of the article, please check it out
Swagatam said…
here it's slow rise and slow decay both....
Swagatam said…
That cannot happen. TIP122 is capable of providing upto 2 amp easily across its emitter and ground.

replace the DRL with a automotive bulb rated at 12V 2amp and see the response,,,,it should light up with full brightness, if it doesn't would indicate a faulty TIP122 for sure.

whether its 1K or 10K the result would be identical.
Dhar Vader said…
HI,

Would I be correct in my understanding, that if the indicator is flashing the DRL will toggle between 100% and 50% brightness (bright/dim/bright/dim)... until the indicator is cancelled. Upon which is returns to 100%.
If this is the case how could the circuit be modified so that the DRL remains at a constant 50% while the indicator is flashing.
Swagatam said…
Hi, in the above diagrams the relay feed is derived from the flasher switch, not from the flasher relay or the lamp, so the problem will be eliminated as per the above diagrams.

If the feed is intended to be taken from the flasher output, this would require a high value, may be a 2200uF capacitor to be connected directly in parallel with the relay coil in order to achieve the desired continuous 50% illumination from the DRL while the flasher is operational.
Dhar Vader said…
Hi,

Yes agree with the high value cap. However can you suggest another method in place of the high value cap?

Also how would you replace the SPDT relay with a transistor set up.

Thanks
Swagatam said…
If a transistor driver is used for triggering the relay and a delay capacitor added at the base of the transistor, this would provide the intended results with a relatively smaller capacitor.

Removing the relay could make the design a bit lengthy, if possible i'll try to update the required circuit soon.
Dhar Vader said…
Hi,

Any update on this, would be good to see your solution.

Regards.
Swagatam said…
Hi, I have updated the required design at the end of the article

R4, R5 = 10k

T3 = BC547
Dhar Vader said…
Hi, Thanks for the update. How could the circuit be modified so that the DRL remains at a constant 50% while the indicator is flashing.
Swagatam said…
Hi use both R1, R2 = 1k
iGOp dacay said…
hi swag, i bought a drl controller and it has only one trigger wire, its for the headlight that dims the drl, is there any way to add another trigger wire for the turn signal or can i connect headlight and turn signal on that trigger wire at the same time, thanks
Swagatam said…
Hi iGOp, you can use the same trigger wire for the headlight as well as for the turn signal, but it will need to be done through separate diodes on each wire, this will make sure that the two inputs are safely isolated....

anodes will go to the respective trigger inputs while the cathodes may be shorted and connected with the DRL wire.
Swagatam said…
...you may use 1N4007 diodes for the above implementation.
iGOp dacay said…
thanks for the quick reply Swagatam, unfortunately the drl controller is really sealed with silicon so i can't open it, can i connect this diodes directly to the wires of headlight and turn signal so it would be like this i.imgur.com/EfL20Ji.jpg please check the photo
thanks man
Swagatam said…
Hi iGOp,

yes definitely you can put the diodes anywhere in the line of the wire externally, either by cutting the wire in the middle or by attaching the diodes at the end of the wires.
Swagatam said…
...the connection details in the image is perfect....just make sure the polarity is done correctly..
iGOp dacay said…
cool!..thanks for the help man, much appreciated
hobby mantra said…
hi sir
thanks for your circuit can you let me know what is the part list for last circuit from ( Mr. Dhar Vader )

thanks
Swagatam said…
Hi hobby mantra, I'll try to update it soon in the article
Artem Dark said…
Hi, Swagatam!
I made a device using your schematics with two TIP142 and a relay. R 3 was 1K , C1 was 220uf 25v.
The LEDs light up quite instantly but when turn signal appears they start to fade very slowly and go on till fully off instead of 50% fading. Where may I be wrong?
Swagatam said…
Hi Artem, you can try increasing the value of R2 until you find the illumination to be 50% while the turns are ON...test the effect by keeping the 220uF removed temporarily

you can also reduce the 220uF to 100uF for preventing a prolonged fading effect on the DRLs...also connect a 10uF/25V cap across the base and ground of T3, for ensuring an effective switch OFF of T1 during the turn operation.
Artem Dark said…
Thanks for your reply, Swag.
I am talking about two transistor and a relay scheme now. Increasing of R2 gives me a better result but still the fading duration is very long. What about 10uf cap in my case?
Artem Dark said…
And one more detail: if i want to discard fading can i leave one transistor only?
Swagatam said…
Artem, referring to the following circuit:


2.bp.blogspot.com/-1O5RFuYefbY/U1uCjICPqZI/AAAAAAAAGvQ/EZRmtvTkfnE/s1600/drl+smart+relay.png

yes you can entirely eliminate the T1/C1/R3, and connect the relay N/C directly with the DRL if the fading effect is not required.

or you can also try connecting a 33K (approximately) resistor right across C1 for controlling the fading time
please connect a 1000uF/25V across the relay coil so that the relay contact does not oscillate when the turn-signal positive is activated across it
Artem Dark said…
Thanks i will try it. Of course, i am at my workbench for test period, so i have no oscillating yet.
Oh, one more word. How do resistor power depend on DRL leds power? The t's are 142 with a lot of current headroom.
Swagatam said…
Actually I have not included any resistor for protecting the DRL because I am assuming it has it's own in-built...the resistors which are shown in the diagram are not related to the DRL rather are for the transistors, and therefore they are all rated at 1/4 watt.

If your DRL does not have a resistor then you may need to calculate it.
Swagatam said…
...you can try TIP122 alternatively, would be fine...
Artem Dark said…
My drl's have their own resistors of course. I meant would the circuit withstand 10w of led power using 14w resistors.
Swagatam said…
the 1/4 watt resistors are related to the transistors not to the LED, so that won't be an issue.
Yusnizam Yusop said…
Hi swagatam.can you make me a drl circuit ,that is ,when u switch on the ignition,the drl will automatically on,but when u switch on the light at night,it will off,
Swagatam said…
Hi Yusnizam, it is already provided in the above diagrams.
Yusnizam Yusop said…
Hi swag...ur 2nd diagram works ,but my T1,is very hot,fyi i used 2N2222 instead of TIP122...
Swagatam said…
Hi Yusnizam, If your 2N2222 is not able to handle the load current then you must switch to a TIP122, because TIP122 is 5 time more powerful than 2N2222 and moreover it's Darligton which will ensure better light on the DRL
Yusnizam Yusop said…
Hi swag....thank for your quick reply,,i will try it.
Unknown said…
Can you send me the pub layout
Mazarin said…
Unfortunately, this is not acceptable in the EU, because the DRL must be completely switched off, not just dimmed, when one lights on the position light or the headlamp.

Contact me for Customized Circuits

Name

Email *

Message *


 Follow on G+  Follow on Facebook   Follow on Tweeter  Follow on G+  Follow on G+

Follow Homemade Circuits