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Info on SMD's good for vehicle modelling?


Jay2jay99

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Hi all,

Sorry, this must be posted elsewhere but searching from the forum on the mobile app shows no results for 'SMD' which I find unlikely.

I'm weighing up my options on lighting my pocher Aventador and have seen people using SMD's, from this I can see what they are but have never used them, I've tried to find them to buy but the ones I've found people say they should be 'current driven' I'm guessing an inline resister should help? Can anyone provide some recommendations to SMD's and resistors to purchase for this purpose? I'm looking to get a variety warm/cool etc so I can play with them and experiment before I start with the build in a week or so. I may not even go with lighting as it's been highlighted that it's tricky to build anyway but I'd like to at least try them out beforehand.

Many thanks,

Jason.

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You may find this site useful.

http://led.linear1.org/led.wiz

I used it extensively when I was building the Hermes model now at Aeroventure Doncaster

or this one for single LEDs

http://led.linear1.org/1led.wiz

Please note that you cannot mix different coloured LEDs on one circuit as they all need different operating currents.

With a light bulb, the brilliance depends on the voltage and it doesn't matter which way around you connect it, when the voltage drops, the brilliance decreases until the blub goes out, current is immaterial.

With an LED , it doesn't give a monkeys what the DC voltage is as it relies on being fed with the correct size current flowing in the right direction for it / them to work. current too low....LED doesn't light. Current too high or flowing the wrong way round...the LED may light for the briefest time before going 'piff, paff, puff' and being terminally knackered! (Beauty is that they are dirt cheap so you can afford to 'blow' a few while learning!)

(Fine wire can sometimes be garnered FoC if you happen to know someone who repairs laptops! The cables that connect to the screen come as a fine ribbon, if you are careful they can be separated into individual wires)

Remember all electronics is governed by smoke.........if the smoke stays in the box all will be well......but if it escapes...things fail to fuction!

(and you cannot get the smoke back in no matter how hard you try!)

When you buy the LEDs the supplier should be able to give you the Forward Voltage , and the MAXIMUM forward current in mA.

If you know what voltage you want things to work on you just apply the figures to the calculator on the above links.

One resistor will can be used to control the current through several of the same type of LED if all are connected in series (one straight chain)

Different colours will require different value resistors to work from the same input voltage.

When fitting the diodes (don't use too much heat...they don't like to be cooked apply a good hot iron for the shortest possible time to make the joint) the little leg is neg (-ve), also shown on some types as a 'flat' moulded into the LED flange, or by a coloured stripe on the negative end in the case of an smd. It might be worth investigating the use of 'solder paint or paste', to make things easier.

Hope this helps

Rex

(P.S. you 'lose' about 0.3 of a volt for each LED in the chain)

Edited by emlra
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.............

Hope this helps

Rex

(P.S. you 'lose' about 0.3 of a volt for each LED in the chain)

Rex, that's amazingly helpful! Thank you. It's more than I was expecting that would be needed but the info is there to work from. I've had a google to see who sells them and have seen some that are quite cheap, as you say, at least I can blow a few without too much heartache.

So on this diode below, I see it has a forward current of 30mA and I chose 9V supply for example, your link above asks for a forward voltage but it doesn't show one, the '?' says the typical is 3.3V for white, adding that it then says the resister should be 220 Ohm.... I'll look on that site for resisters also.

https://www.rapidonline.com/3014

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Rex, that's amazingly helpful! Thank you. It's more than I was expecting that would be needed but the info is there to work from. I've had a google to see who sells them and have seen some that are quite cheap, as you say, at least I can blow a few without too much heartache.

So on this diode below, I see it has a forward current of 30mA and I chose 9V supply for example, your link above asks for a forward voltage but it doesn't show one, the '?' says the typical is 3.3V for white, adding that it then says the resister should be 220 Ohm.... I'll look on that site for resisters also.

https://www.rapidonline.com/3014

No problem mate, just use the advised value for the colour LED that you are using.......green are different to reds which are different to blues etc......all reds can be fed by a common resistor, all greens on another etc etc...... fill in the supply box eg 9........and the forward current given in the suppliers specs eg 30, check on the Forward Voltage [?] for the colour you wish to use and add the value given...in this case 3.3 to the box. (this voltage is only necessary so that when the wizard designs your circuit. it can work out for example that if you were going to use in this case 4 white diodes.....3.3 +3.3 + 3.3 + 3.3 = 13.2v ,so your 9v supply would not be sufficient to light all 4 leds, so it then would design the circuit to produce 2 chains instead of one...... have a play with the Wizard, get it to design you some circuits and see how you get on....... a ( A good tip is to look for the ARRAY that consumes the least mW, (any battery will last longer!) The resistor colour code advice is useful too when building your circuit.

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3014 SMD LED Warm White 120° 2000-3000mcd@20mA 2800-3500K, for the one you have selected means :-

3mm long, 1.4mm wide.............so pretty small

LED .............. ...........Light Emitting Diode......but we already knew that!

120° ..........................the angle from which it is visible

2000 - 3000mcd...........the brightness at the stated 20mA current in microcandela

2800 - 3500K ..............is some kind of code for the colour temperature......beyond me!

:hypnotised:

Rex

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K is Degrees Kelvin.

A rating in degrees on the Kelvin scale at which bodies glow certain colours.

It goes from deep red to bright white-blue

The lower the number the redder it is, the higher the number the bluer it is.

2800-3500K is in the range of the yellow-orange light of an incandescent light bulb [the old fashioned light bulbs - aka warm white]

'Daylight' is in the range 5600 - 7000K aka 'daylight white' on SMD or LED

hth

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One other point to bear in mind - SMD means surface mounted device. This means they will have very short or almost non-existent leads designed for automated assembly equipment. You'll find through-hole (leaded) devices much easier to solder, but obviously you'll need to find more space for them.

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K is Degrees Kelvin.

A rating in degrees on the Kelvin scale at which bodies glow certain colours.

It goes from deep red to bright white-blue

The lower the number the redder it is, the higher the number the bluer it is.

2800-3500K is in the range of the yellow-orange light of an incandescent light bulb [the old fashioned light bulbs - aka warm white]

'Daylight' is in the range 5600 - 7000K aka 'daylight white' on SMD or LED

hth

Ta!

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One other point to bear in mind - SMD means surface mounted device. This means they will have very short or almost non-existent leads designed for automated assembly equipment. You'll find through-hole (leaded) devices much easier to solder, but obviously you'll need to find more space for them.

Very small point soldering iron, finr solder (you can stretch the normal stuff to make it thinner0, and a clamp made of a modified clother peg.

'stip and 'tin' the fine leads first, smallest wipe of solder on the 'lands' of the led, magnifying glass and a quick 'dab' with the iron...

and Robert is your mother's brother!

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