Chris_L Posted February 10, 2021 Share Posted February 10, 2021 Hi .. Sorry as a novice in wiring up of a layout .. I come across difficulties .. Wiring up the control board and house lighting etc I am using led's .. which need a resistor .. but which one .. I know it is 1k .. but what ohm etc .. It is such a minefield out there .. Thank you for all information .. Link to post Share on other sites More sharing options...
LimboBrit Posted February 10, 2021 Share Posted February 10, 2021 This is not so easy to answer because it will depend on the voltage being used to supply the LEDs, the colour, the required brightness and maximum LED current rating. Also how the LEDs are to be connected needs to be considered (series/parallel). I'm sure by a bit of Googling you should be able to find some guidance. There is no simple answer to this question. Link to post Share on other sites More sharing options...
RMweb Premium ELTEL Posted February 10, 2021 RMweb Premium Share Posted February 10, 2021 I am sure I have seen a rough guide to resistor values using led’s on 12v dc Terry Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted February 10, 2021 RMweb Gold Share Posted February 10, 2021 17 minutes ago, Chris_L said: Hi .. Sorry as a novice in wiring up of a layout .. I come across difficulties .. Wiring up the control board and house lighting etc I am using led's .. which need a resistor .. but which one .. I know it is 1k .. but what ohm etc .. It is such a minefield out there .. Thank you for all information .. 1k is 1000 ohms. Andi Link to post Share on other sites More sharing options...
LimboBrit Posted February 10, 2021 Share Posted February 10, 2021 https://www.evilmadscientist.com/2012/resistors-for-leds/ Looks like a good starting point Link to post Share on other sites More sharing options...
Yardman Posted February 10, 2021 Share Posted February 10, 2021 If you are running them on 12volts 1 to 2K (1000 ohms to 2000 ohms) is a good ballpark figure. LED's are a current device and not all have the same current rating. The current rating on a LED should be treated as a maximum, they will all work with less current. Make sure you connect them the correct way round or they will be instant;ly destroyed. Link to post Share on other sites More sharing options...
dasatcopthorne Posted February 10, 2021 Share Posted February 10, 2021 I learnt a lot here. https://electronicsclub.info/ Dave. 1 Link to post Share on other sites More sharing options...
Il Grifone Posted February 10, 2021 Share Posted February 10, 2021 I always run mine on 10 milliamps. LEDs once lit do not vary a great deal in brightness, so the actual value is not critical. The voltage drop across the LED is around two to three volts dependant on colour which for a twelve volt supply leaves about ten volts to drop conveniently requiring a one kilohm (1000 ohm) resistor. For a five volt supply the values are: three volts and 300 ohms. The nearest preferred values are 270 and 330 ohms (either will do). A ¼ watt rating is more than adequate. Resistors are available cheaply direct from China on eBay (as long as you are not in a hurry!). 1 Link to post Share on other sites More sharing options...
LimboBrit Posted February 10, 2021 Share Posted February 10, 2021 21 minutes ago, Il Grifone said: LEDs once lit do not vary a great deal in brightness, so the actual value is not critical. Actually LED luminance is very roughly linear to LED current Link to post Share on other sites More sharing options...
Il Grifone Posted February 10, 2021 Share Posted February 10, 2021 35 minutes ago, LimboBrit said: Actually LED luminance is very roughly linear to LED current Not according to this: https://ledshield.wordpress.com/2012/11/13/led-brightness-to-your-eye-gamma-correction-no/ It is true that the actual luminance varies with current (approximately), but the human eye is not linear, so the perceived brightness varies much less. 1 Link to post Share on other sites More sharing options...
LimboBrit Posted February 10, 2021 Share Posted February 10, 2021 4 minutes ago, Il Grifone said: It is true that the actual luminance varies with current (approximately), but the human eye is not linear, so the perceived brightness varies much less. That is correct but it is not true to say that brightness does not vary greatly witnessed by the functionality of LED dimmers. Link to post Share on other sites More sharing options...
RMweb Premium Steven B Posted February 10, 2021 RMweb Premium Share Posted February 10, 2021 Have a look at Chapter 12 of MERG's Electronics for Model Railways eBook - available free to everyone from their website. Steven B. 1 Link to post Share on other sites More sharing options...
meil Posted February 10, 2021 Share Posted February 10, 2021 3 hours ago, Chris_L said: Hi .. Sorry as a novice in wiring up of a layout .. I come across difficulties .. Wiring up the control board and house lighting etc I am using led's .. which need a resistor .. but which one .. I know it is 1k .. but what ohm etc .. It is such a minefield out there .. Thank you for all information .. Go here: http://www.hebeiltd.com.cn/calculator/v5/led.php That will give you the suitable resistor value. Link to post Share on other sites More sharing options...
meil Posted February 10, 2021 Share Posted February 10, 2021 50 minutes ago, LimboBrit said: That is correct but it is not true to say that brightness does not vary greatly witnessed by the functionality of LED dimmers. That's because LED dimmers work with a PWM output to the LED. not by simply reducing current. Link to post Share on other sites More sharing options...
LimboBrit Posted February 10, 2021 Share Posted February 10, 2021 (edited) 7 minutes ago, meil said: That's because LED dimmers work with a PWM output to the LED. not by simply reducing current. By using PWM you can change the current going through it and therefore brightness without changing the colour point of the LED Edited February 10, 2021 by LimboBrit Link to post Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now