Dimming LED Lights (12V)

[pattayapip]

I have also posted this in the Car section, but maybe people here might have a better idea, worth a try

 

Does anyone know how to dim a rear LED Car Plate like Photo attached for an example ?

 

I know there is a fair bit of discussion on how the brightness of these things annoys/affects other road users, not debating that, just if i purchased a set how could i dim these LEDs so as not to affect/annoy anyone ?

 

Googled a few things and seen that you can insert a resistor into the positive feed to reduce the brightness, not been able to work out exactly what i would need, or find any resistor on Lazada to order and try ? although there appear to be lots of listings, would need to know what exactly to buy, or a few to try
Any help please ?

[Crossy]

It depends I'm afraid.

 

If the sign has a simple dropper resistor adding another in series will happily reduce the brightness (it will get hot!). Using a PWM (Pulse Width Modulated) dimmer (readily available) will allow you to control the brightness and also won't get hot. 

 

With a fancy electronic driver then simply adding a resistor will do little, the driver will compensate until the voltage gets too low and it simply goes off.

[johng]

The "EVEREST"   display I saw (on the road)  seemed to have a dimming and colour changing "thingy"  already installed/built in.  

[sometimewoodworker]

3 hours ago, Crossy said:

It depends I'm afraid.

 

If the sign has a simple dropper resistor adding another in series will happily reduce the brightness (it will get hot!). Using a PWM (Pulse Width Modulated) dimmer (readily available) will allow you to control the brightness and also won't get hot. 

 

With a fancy electronic driver then simply adding a resistor will do little, the driver will compensate until the voltage gets too low and it simply goes off.

For some/most mains drivers you can also add a capacitor in the supply to reduce the brightness instead of changing a resistor. 
 

 

I don’t have the electronic knowledge to know if this works for 12v supply lamps. 

 

 

 

 

 

 

[pattayapip]

Thankyou for your Replies

[Yellowtail]

Would you not want to install a flasher and controller such that you can make it change color?