Davidrebolton Posted March 9, 2021 Share Posted March 9, 2021 (edited) Hi guys, first post here and it's good to be here. I have seen some awesome models in my short time here and some good convocation. Anyway, I am just getting back into modelling after close to a 25 year gap. I have bought all the required tools, a good airbrush and compressor ETC and look forward to getting started as an adult 😀 Around 15 years ago I started the Revell QM2, drilled out the hull etc, but after making a mistake with the painting it's been put onhold until very recently. I've since completely lightblocked the hull with black fabric paint in preparation for LED's and fiber optics. Here is where my problem lies, and the reason for this post. I'm a complete noob when it comes to electric and the such though have been learning. I see (using a calculator) that with a 5v power supply I can power my strawhat orange LED's, 20 or so of them, with 330ohm resistors - 7 I think it said. Now, how do I go about adding another circuit of another set of SMD's, say 22 or so + red and green navigation? Ho do I go about adding them all together - added resistors ETC. I'd be most greatful if someone would be willing to help me calculate the circuit I require so I can learn and progress with my model as I'm stuck at the moment until I get the hull lights/lights planned and working. Have a good day all Regards Edited March 9, 2021 by Davidrebolton Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 9, 2021 Share Posted March 9, 2021 What figures did you use to get to 330ohm? (Foreword voltage and current of the LEDs) Your red & green LEDs could be connected in parallel to your 5v supply along with another separate current limiting resistor. Or you could add them in parallel to your existing LEDs with the same 330ohm resistor. Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 9, 2021 Author Share Posted March 9, 2021 36 minutes ago, Cheshiretaurus said: What figures did you use to get to 330ohm? (Foreword voltage and current of the LEDs) Your red & green LEDs could be connected in parallel to your 5v supply along with another separate current limiting resistor. Or you could add them in parallel to your existing LEDs with the same 330ohm resistor. Yes they were the figures I used. So basically with a constant 5v I can power all of these lights using the 330's? How would I go about calulating how many additional resistors I may need for the other circuits? Thank you, I'm eager to learn Link to comment Share on other sites More sharing options...
bmwh548 Posted March 9, 2021 Share Posted March 9, 2021 No, you can't. The human eye perceives different colors at different intensities even if in theory the light output is the same. You need to separate them by colors and do each color depending on the effect you want to achieve. Also because of Murphy's law I never group more than two LEDs on the same resistor. If the connection breaks on the resistor you end up with 1-2 LEDs that don't work, but if you have all of them on the same resistor then none will work. Buy (or order) a bunch of different value resistors and test for light intensity before committing to gluing everything in place. Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 9, 2021 Share Posted March 9, 2021 So you want to do something like this for your orange LEDs? I've not included the red & green LEDs just yet. Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 9, 2021 Author Share Posted March 9, 2021 6 minutes ago, bmwh548 said: No, you can't. The human eye perceives different colors at different intensities even if in theory the light output is the same. You need to separate them by colors and do each color depending on the effect you want to achieve. Also because of Murphy's law I never group more than two LEDs on the same resistor. If the connection breaks on the resistor you end up with 1-2 LEDs that don't work, but if you have all of them on the same resistor then none will work. Buy (or order) a bunch of different value resistors and test for light intensity before committing to gluing everything in place. Thank you!! I shall have to order a selection and just test + a 5v charger or the such. I see we can buy a high-amp voltage reducer, something which I see someone else has done and embedded it into the stand - nice and small - I may do the same for the power supply. So I can just add other circuits to the base hull lighting circuit shall we say? Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 9, 2021 Author Share Posted March 9, 2021 2 minutes ago, Cheshiretaurus said: So you want to do something like this for your orange LEDs? I've not included the red & green LEDs just yet. Aweosme thank you, yes the orange. Still not completely sure how many I'll use but close to that number. Its a start for me. I've watched so many videos, read loads of explanations but am just still stuck lol I'm also planning to add an RGB disco type LED - only the one Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 9, 2021 Share Posted March 9, 2021 1 minute ago, Davidrebolton said: I'm also planning to add an RGB disco type LED - only the one Now it gets complex as you will need a controller circuit for that! Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 9, 2021 Author Share Posted March 9, 2021 4 minutes ago, Cheshiretaurus said: Now it gets complex as you will need a controller circuit for that I see. All in all I want the orange in the bottom, the SMD's along along hull, navigation lights, blue LEDs 5 or 6 + the disco light. This is everything I want to try and install. Link to comment Share on other sites More sharing options...
bmwh548 Posted March 9, 2021 Share Posted March 9, 2021 Not necessarily, there's LEDs with the controller integrated. Just be very careful wiring them, most of the controllers don't have a reverse voltage protection and it'll burn instantaneously. You can add as many circuits as you wish (provided you stay in the power supply's limits, but that shouldn't be an issue). Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 9, 2021 Share Posted March 9, 2021 2 options for adding the red & green :- you could have them both share the same resistor(still needs to be calculated) or each on their own resistors. Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 9, 2021 Author Share Posted March 9, 2021 Thanks guys. I appreciate the quick offerings of help. It does look to be getting confusing now though i'll persivear, I'm desperate to learn. Perhaps I would be best starting with the initial oranges with resistors, then add and learn from then on? Link to comment Share on other sites More sharing options...
dnl42 Posted March 9, 2021 Share Posted March 9, 2021 Perhaps you're already aware of this, but you can use a solderless breadboard to ensure your circuit works exactly as you need, from initial experimentation to final mock-up. 2 Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 9, 2021 Share Posted March 9, 2021 17 minutes ago, dnl42 said: Perhaps you're already aware of this, but you can use a solderless breadboard to ensure your circuit works exactly as you need, from initial experimentation to final mock-up. Thats a good idea, its a good investment to learn more circuits on in the future. Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 9, 2021 Author Share Posted March 9, 2021 39 minutes ago, dnl42 said: Perhaps you're already aware of this, but you can use a solderless breadboard to ensure your circuit works exactly as you need, from initial experimentation to final mock-up. 19 minutes ago, Cheshiretaurus said: Thats a good idea, its a good investment to learn more circuits on in the future. Yes guys I am aware of them and should buy one for what little they cost. I'll order one with the resistors when I order them. Most appreciated guys. 1 Link to comment Share on other sites More sharing options...
Murdo Posted March 10, 2021 Share Posted March 10, 2021 Have you thought of using Fibre Optic cable (FO)? This 1:350 ship (Scratch built) has only three 5mm LEDs, two yellow and one Ultra white running off a 9v PP3 battery and 3 resistors. Different strengths of resistors can be easily used to brighten / darken the LEDs to the light luminance strength you want. As mentioned, a breadboard makes this kind of stuff very easy to manipulate. All porthole lights run off of yellow LED 1, yellow LED 2 is stuck in the superstructure for the wheelhouse / superstructure lighting and the ultra white LED is for all outside deck and mast lighting. The actual masts are FO cable with gashes to allow light to leak out where I want it. Each LED feeds a bunck of FO cables cut to length and the ends polished with one of my daughters finger nail thingy boards. Port Nav light has a dab of clear red and starboard a dab of clear green Tamiya paint on the polished ends. This shows the FO mess underneath the hull. The black shape at the bottom right is the heatshrink tube that holds the LED and the FO strands. Here you can see the tiny FO cable that depicts the Port navigation light: Day shot: Night shot: If you do a search, there are a fair number of build threads showing ship builds with minimal LEDs using Fibre Optic cable. Hope this is of use to you. Link to comment Share on other sites More sharing options...
nheather Posted March 10, 2021 Share Posted March 10, 2021 The maths. As a rule of thumb an LED has 2V across it and needs 10mA for a decent illumination. In reality the actual voltage varies depending on the colour and can be 3V or so and the current can be up to 30mA, the higher the current the brighter but there is a limit to how much current. But as a general rule 2V and 10mA work well. Take a single LED. If the supply voltage is 5V then you will have 2V across the LED so you need (5-2) 3V across the current limiting resistor. You want the current to be 10mA (0.01A) so using Ohm’s law the resistance needed is Voltage/Current so 3/0.01 = 300 ohms But what if you have multiple LEDs in parallel. Let’s use two as an example. The voltage across the resistor is still 3V. But the current required is now 20mA because you need 10mA for each LED. The the resistor needed for two LEDs in parallel is 3/0.02 = 150 ohms. If you want seven LEDs in parallel the current through the resistor is now 70mA. So the resistor needed is 3/0.07 = 43 ohms. Note resistors come in certain sizes so just puck the one nearest to the calculated value. In your example above, I think the 330 you have been specified is for ONE LED. If you use a single resistor to drive SEVEN LEDs the current through each LED will be very small, may not be enough to light them at all or if it does they may be very dim. Cheers, Nigel Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 10, 2021 Author Share Posted March 10, 2021 21 hours ago, Murdo said: Have you thought of using Fibre Optic cable (FO)? This 1:350 ship (Scratch built) has only three 5mm LEDs, two yellow and one Ultra white running off a 9v PP3 battery and 3 resistors. Different strengths of resistors can be easily used to brighten / darken the LEDs to the light luminance strength you want. As mentioned, a breadboard makes this kind of stuff very easy to manipulate. All porthole lights run off of yellow LED 1, yellow LED 2 is stuck in the superstructure for the wheelhouse / superstructure lighting and the ultra white LED is for all outside deck and mast lighting. The actual masts are FO cable with gashes to allow light to leak out where I want it. Each LED feeds a bunck of FO cables cut to length and the ends polished with one of my daughters finger nail thingy boards. Port Nav light has a dab of clear red and starboard a dab of clear green Tamiya paint on the polished ends. This shows the FO mess underneath the hull. The black shape at the bottom right is the heatshrink tube that holds the LED and the FO strands. Here you can see the tiny FO cable that depicts the Port navigation light: Day shot: Night shot: If you do a search, there are a fair number of build threads showing ship builds with minimal LEDs using Fibre Optic cable. Hope this is of use to you. Thanks Murdo, it is helpful and I do also have various thickness fibers ready for tinkering hehe. 15 hours ago, nheather said: The maths. As a rule of thumb an LED has 2V across it and needs 10mA for a decent illumination. In reality the actual voltage varies depending on the colour and can be 3V or so and the current can be up to 30mA, the higher the current the brighter but there is a limit to how much current. But as a general rule 2V and 10mA work well. Take a single LED. If the supply voltage is 5V then you will have 2V across the LED so you need (5-2) 3V across the current limiting resistor. You want the current to be 10mA (0.01A) so using Ohm’s law the resistance needed is Voltage/Current so 3/0.01 = 300 ohms But what if you have multiple LEDs in parallel. Let’s use two as an example. The voltage across the resistor is still 3V. But the current required is now 20mA because you need 10mA for each LED. The the resistor needed for two LEDs in parallel is 3/0.02 = 150 ohms. If you want seven LEDs in parallel the current through the resistor is now 70mA. So the resistor needed is 3/0.07 = 43 ohms. Note resistors come in certain sizes so just puck the one nearest to the calculated value. In your example above, I think the 330 you have been specified is for ONE resistor. If you use a single resistor to drive SEVEN resistors the current through each LED will be very small, may not be enough to light them at all or if it does they may be very dim. Cheers, Nigel Thanks for the explanation Nigel, it's appreciated matey Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 10, 2021 Author Share Posted March 10, 2021 So guys I've just bought a bread board and a big multipack of resistors so I'll ha e everything to start tinkering soon. I've also found a different disco type light as seen at this link https://www.gaugemasterretail.com/magento/train-tech-ttsl10.html Thing is it needs power between 9v-16v, so I think I'll be purchasing a 9v power source for this project. Thanks to all for your help, I'll likely be posting again soon for more advice and tips. Take care all 👍 Link to comment Share on other sites More sharing options...
Murdo Posted March 10, 2021 Share Posted March 10, 2021 8 minutes ago, Davidrebolton said: and I do also have various thickness fibers ready for tinkering hehe. Be careful, it can become rather addictive. My wife was getting really hacked off with my LED / FO produced light shows. Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 10, 2021 Author Share Posted March 10, 2021 (edited) 25 minutes ago, Murdo said: Be careful, it can become rather addictive. My wife was getting really hacked off with my LED / FO produced light shows. Lol I could imagine. I have many 1/24 cars I want to end up lighting with fibers. Although lots more fiddly I feel it will be easier for me given the few LEDs required haha The MRS loves cars so she won't mind the constant tinkering 😁 Trust me to pick the largest transatlantic liner in the world as my first lighting project lol 😆 Her hull has been totally light sealed to prevent leaks with many coats of black fabric paint- very thick! And plan to do so throughout the model to ensure light only goes where it should Your help is appreciated and needed hehe With thanks Edited March 10, 2021 by Davidrebolton Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 10, 2021 Author Share Posted March 10, 2021 Regarding this disco light guys https://www.gaugemasterretail.com/magento/train-tech-ttsl10.html As I stated it needs between 9v-16v. Am I right in thinking that 9v wouldn't be enough given all the other lights on/in the circuit? Also I see we can buy step-down power modules, a high amp voltage reducer which can be mounted into the models plinth. Would someone be able to link me to one? Perhaps higher than 9v depending on the outcome of the first question. I have looked around before asking though not had much luck as, to be honest, I don't know what I'm looking for lol Thanks all 👍💥 Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 11, 2021 Share Posted March 11, 2021 Its not just the voltage its also how much current the supply can provide. If your disco LED needs 9v to operate then you could run your other LEDs from the same supply just need a higher value resistor. Add up the current required by all the LEDs and add maybe 50% so your power suppy is not Running at max. As an example if you have say 30 LEDs at 10mA that is 300mA so you should look for a minimum of 450mA for your power supply. Link to comment Share on other sites More sharing options...
Davidrebolton Posted March 11, 2021 Author Share Posted March 11, 2021 14 hours ago, Cheshiretaurus said: Its not just the voltage its also how much current the supply can provide. If your disco LED needs 9v to operate then you could run your other LEDs from the same supply just need a higher value resistor. Add up the current required by all the LEDs and add maybe 50% so your power suppy is not Running at max. As an example if you have say 30 LEDs at 10mA that is 300mA so you should look for a minimum of 450mA for your power supply. I see. I had found this one https://www.ebay.co.uk/itm/164630867449 But going from what you say I see its only rated at 300mA. Would you be able to point me in the direction of which I require with a link 🤔 - if you don't mind. Link to comment Share on other sites More sharing options...
Cheshiretaurus Posted March 11, 2021 Share Posted March 11, 2021 The 450mA supply I mentioned was an example, What you actually need would depend on your application. Whats the current of the LEDs you will use have you got a link to them? Link to comment Share on other sites More sharing options...
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