Rookie Question re Firebox Flicker LED's

[steveNCB7754]

Hi,

 

I'm taking my first steps with DCC and am following Paul Chetter's article on fitting DCC to a Hornby J94 Austerity, from the April 2012 Hornby Magazine (I too, am using the Zimo MX648 sound decoder).

 

To add the firebox flicker, Paul is using a 3mm red LED, but its source/specs are not specifically mentioned in the article's 'What We Used'.  Which I did not think would be much of a problem, until I searched for '3mm LED' on the Maplin website, where I am now staring at quite a large list!  First off, there is a choice between 5 and 12 volts and then there are LED's with various sub-idents, such as 'HE', 'SB' and some give a value (like 2mA) and most don't.

 

HELP! (Paul?)  Any idea which one is required (have tried scouring the Zimo manual PDF for the decoder, to see if I can find out what the voltage output for the lights is, but I cannot find it at the moment).

 

 

Thanks in advance,

 

Steve

 

 

[pauliebanger]

Steve.

 

Sound fitting a J94. Interesting choice for a first 'dabble' at DCC. You should find that the HM feature explains all you need for a successful installation. (Once you have all the correct componets, Ha Ha). If you need any further help, post in DCC Sound section or PM me.

 

The Function Outputs normally supply 12v, though there is a 'dimming option' which can be used to control the current to LEDs. (CV60)

 

The 'failsafe' way to protect 'normal' LEDs (1.5 - 2v) is to fit a suitable resistor in series. This will ensure that even a decoder reset will not expose the LED to over-current. You can then use dimming to adjust brightness if necessary.

 

I get my LEDs from a number of sources but, by coincidence, I am currently using KEMCO N21GL from Maplins. This is a pack of 10, with the code SO65. The full Bar Code number is 4  024028  050652. I suggest a resistor of 1Kohms minimum. Higher values will reduce the brightness more, too low and the LED will 'blow'. 

 

I recently bought some 12v LEDs from Digitrains to try out, but I haven't used them yet. They cost a little more, but this may be offset by the added convenience of having less work to do, less space to find, and avoiding the cost of a resistor, extra solder and insulation.

 

Good luck,

 

Paul

[steveNCB7754]

Steve.

 

Sound fitting a J94. Interesting choice for a first 'dabble' at DCC. You should find that the HM feature explains all you need for a successful installation. (Once you have all the correct componets, Ha Ha). If you need any further help, post in DCC Sound section or PM me.

 

The Function Outputs normally supply 12v, though there is a 'dimming option' which can be used to control the current to LEDs. (CV60)

 

The 'failsafe' way to protect 'normal' LEDs (1.5 - 2v) is to fit a suitable resistor in series. This will ensure that even a decoder reset will not expose the LED to over-current. You can then use dimming to adjust brightness if necessary.

 

I get my LEDs from a number of sources but, by coincidence, I am currently using KEMCO N21GL from Maplins. This is a pack of 10, with the code SO65. The full Bar Code number is 4  024028  050652. I suggest a resistor of 1Kohms minimum. Higher values will reduce the brightness more, too low and the LED will 'blow'. 

 

I recently bought some 12v LEDs from Digitrains to try out, but I haven't used them yet. They cost a little more, but this may be offset by the added convenience of having less work to do, less space to find, and avoiding the cost of a resistor, extra solder and insulation.

 

Good luck,

 

Paul

 

Hi Paul,

 

Thanks for taking the trouble to answer this, that is exactly what I was looking for

 

 

Regards

 

Steve