Can someone explain if it is possible to string LEDs together for use in a modern warehouse type building as interior lighting? Do I need a resistor for each LED or will one be O.K.? I had thought of using White LED Christmas lights but they are too big for H.O., too spred apart and come in bunches of around 80 lights. Any ideas would be welcome, CPPedler
If you wire LEDs together in parallel, best practice is to put a resistor on each one. For series-wired LEDs, one resistor is fine, but keep track of the forward voltage of the LEDs - 10 LEDs with a forward voltage of 2.1 volts in series will need at least a 21 volt power supply to light them all. Parallel is best. LEDs are liek any other manufacturered item - there are tolerances within which a part is considered ‘good’ so a tring of series-wired LEDs might not all be the same brightness. In an ideal ciruit, voltages add in series and current is equal across each element. A single falure will turn off all LEDs. In parallel, the voltage stays the same but the currents add. One LED failing will keep the others lit. If you use a single resistor in a parallel arrangement and an LED fails, the remaining ones will get too much current - sort of like a chain reaction. That’s why one resistor per LED is best.
If you are doing a lot - check for the UK equivalent of the US electronic supply houses like Mouser or Digikey. When buying a large pack of resistors, I can get 20 or so from one of these places for what a 5 pack costs at the local Radio Shack. In fact I think Mouser’s price for a 1/4 watt resistor in a quantity of 100 is about 2 cents each.
–Randy
Another, potentially easier route (especially when stringing a large qty of parallel LEDs) is to use a 1.5V or 2V voltage regulator to make a small 2V circuit specifically for the LEDs:
Where the 12V battery is any 12V source. Just buy a Voltage Regulator rated for the voltage of the LEDs you’ll be using.
Here’s a recommendation:
http://www.mouser.com/search/ProductDetail.aspx?R=LD1085V18virtualkey51120000virtualkey511-LD1085V18
3A or 3,000mA capacity. LEDs typically draw no more than 20mA@2V, so there’s plenty of capacity.
-Dave
Thankyou Randy and Dave .
Both these ideas come across as sound advice and I will check them out.
Thankyou once again . CPPedler
Glad to help!