DRL - High Power DRL Light Circuit

High Power DRL Light Circuit

The post discusses a multipurpose high power DRL circuit which can be used as park lights, head lights and also to specially respond to turn signal lights in order to light up the kerbs while passing through unpredictable blind turns or corners and subways. The idea was requested by Mr. Ian Auxley.
The Request

Good day Swagatam,

I have just found your web site and I am very impressed with your wonderful knowledge and friendliness.

I am very interested in Automotive projects. I have designed and built a circuit using old tech stuff like auto relays, diodes, and resistors etc, all soldered together in a wooden box.

This circuit works perfectly.It is used to turn on fog lights as day time running Lights and is also used to turn each one independently when either turn indicator is flashing on, the light uses capacitors to hold the relays on and not flash, it draws power from the indicators I this mode.

In drl mode it draws power from the battery, there are 2 micro switches on the indicator stalk, one is a momentary to flash the drls and the other is to turn the drls on or off at night when the headlights are on.

Some upscale cars use them when turning right or left to light up the kerbs and driveways when the indicators are used. I would like to make this into a solid state circuit that is smaller and easier to fit.

I would like to have a circuit drawn up as a hobby project so anybody could use it.

The lights I used in the older car I had were just dichroic 12v 60w household down lights with 60deg angle, I would love to use high powered LED lights instead.

I could send you a hand drawn copy of the circuit if you are interested as used but not sure of values for diodes and resistors.

I have other project ideas as well if you are interested.

Could you help with the design.

Kind regards Ian Oxley Australia

Designing a Power DRL Circuit for your Car

Referring to the request above, the idea could be summarized in the following manner:

1) two powerful LED lights to be used on the left/right sides of the car, which can be used as DRLs, park lights as well as head lights.

2) These lights needs to be controlled through separate switches as fog light, park light, and DRL lights.

3) The DRL light circuit should include the feature which ensures that when a side indicator is ON (flashing), the opposite DRL LED should be switched ON, but the DRL on the flashing indicator side should be switched OFF, however once the turn light is OFF the DRLs must return to their normal condition. The above feature needs to be implemented regardless of whether the DRLs are originally switched ON or not.

4) The unit needs to be solid-state in nature, and should avoid mechanical operators such as relays.

High Power DRL Light Circuit

The image above shows the intended solid state version of a high power DRL circuit with the recommended features, the details may be understood with the help of the following points:

1) two exactly identical stages can be seen on the left and the right sides, which form the respective DRL stages, along with a couple of delay timer stages for the specified switching actions through the turn signal feeds.

2) the 2N2907 and the associated TIP127 transistors form a simple current controlled LED driver stage for controlling the high power LED DRLs safely.

3) The other TIP127 transistor along with the BC547 forms a delay OFF timer stage intended for converting the flashing feed from the turn signal lights into a relatively constant DC.

4) The TIP127 delay OFF timers on L/R sections are configured in a such manner that it switches OFF it switches ON the opposite DRL while keeping its relevant side DRL ON.....

For example suppose while the left side indicator is active, the right DRL is forced to switch ON regardless of whether it's originally switched ON or not, and at the same time it forces the DRL at its own side to switch OFF regardless whether it's originally switched ON or not.

Exactly similar conditions are implemented for the right side indicator switching also.

The switches shown at the extreme sides allow the user to switch the DRLs ON or OFF together or individually at will.

The two LEDs confirm the powering of the DRLs and vice versa.

10 thoughts on “High Power DRL Light Circuit

  1. Have questions? Please feel free to post them through comments! Comments will be moderated and solved ASAP.
  2. Your schematic looks interesting. Also, what would happen if you turn on the hazard switch, so both left and right blinkers are working in the same time?! How the inter-locking will work in this case?

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