Changing 5mm LED to 3mm LED

[Tamiyastef]

What do I have to look out for when changing 5mm LED's in a light system to 3mm LED's. Can they handle the same voltage? (or current - you can already tell electronics are my strong point ) Do the 3mm's burn out when hooked up where a 5mm was before? Can I avoid that to happen by putting a resistor somewhere at the right spot? Or, and that would be very nice so also very unlikely, can I just replace the 5mm's with 3mm's without any worries... 

[Ray_ve]

The difference between a 5mm LED and 3mm LED is the amount of translucent plastic that surrounds the actual LED that is inside.

The only issue is that there are many types of LEDs. For example normal, high power, low current... So you would need the same type of 3mm LED to replace the 5mm....

 

[Tamiyastef]

1 hour ago, Ray_ve said:

normal, high power, low current...

I think there both normal. The 5mm and 3mm ones come from a different light set. Can I check with measuring the current going to them? If that's the same It should not be a problem to switch them over I guess? 

[Ray_ve]

If you can measure the current that would help. A normal LED is about 10 to 20 milli-amps.

[ruebiracer]

What light system do you use? The good ones working with a constant current output of 20mA. So there´s no problem to replace a 5mm one with 3mm. The Tamiya TLU 01 does not care about 3 or 5mm LED. It are the same output channels.

[Tamiyastef]

I want to use the 3mm LED's from  a Carson "Race" LED set on a Dumbo RC receiver with build in LED controller. See if I can get the current measured on both systems later this evening before I start swapping out the 3 and 5 mm LED's.

[Tamiyastef]

The TLU-01 gives 2.74 Volts, the DumboRC LED receiver gives 5.74 Volts! Haven't had a chance to "unpack" the Carson system to measure that out. It's in a Tamiya rubber bag, ziptied and sitting on a tray on the underside of the Unimog body so kinda hard to get in there to measure it out, so that's my goal for tomorrow.

[Tamiyastef]

The Carson LED system gives 5.74 Volts to all the lights, the 5mm red and white ones and 3mm orange ones. Hooking those 3mm's up on the DumboRC system shouldn't be a problem then. Only strange thing I came accross is the TLU-01 where I measure just 0.25 Volts on the wires to the Halogen white LED from Tamiya. Checked it three times, always the same