DIY Coach Lighting - some questions

[Sir TophamHatt]

I'll probably keep coming back to this thread as I progress.

 

My knowledge of basic electronics is woeful but this is why I'm looking to DIY, so I can learn more.

 

Running DCC.

Plan to have up to 8 coaches per rake and perhaps two or three rakes on the layout at one time.

 

I have a list of components but have stumbled at the first one:

 

Bridge Rectifier:

The 12v (maybe it's 16v?) or so that runs through my tracks... does this mean I need a bridge rectifier that is higher than the volts from the rails? I'm pretty sure the answer is yes and to be honest, I struggled to find one less than 200v or so.

 

But what about amps. Found one that looks okay but it says 0.8/1 amp - what does this mean?

There's also a 1amp one here that is slightly cheaper. I guess if the above one is suitable, this will be too? 

 

Capacitor:

While quite over what I may need, this 16v 2200uf version should be okay to use? this 25v 2200uf version seems to fit the bill.

 

Cheers.

Edited September 5, 2020 by Sir TophamHatt

[Bucoops]

Have a look at this thread 

 

 

[Sir TophamHatt]

Also, a silly question, there seems to be a whole host of different 1k resistors... how do I know which are the right ones for me to buy? 

[Art Dent]

STH

 

Have a look at this post.

 

It gives the specifications (and Rapid Electronics part numbers) together with some pix so that you can see how it goes together.

 

Regarding the cap, yes a 16V or better still a 25V in preference to a 12V.

 

Regarding resistors, the bog-standard 1/4 watt metal metal-film resistors will do just fine - such as these from ebay (£0.99 for 20 / free p&p)

 

Depite what Suzie said in reply to my post, the DI202 DIP Bridge Rectifier is fine for DCC use. [DIP means 'Dual In-line Pin' - a flat, rectangular package with legs sticking out of the sides]

 

I use it and encounter no problems.

 

Art

Edited September 6, 2020 by Art Dent

[Sir TophamHatt]

On 06/09/2020 at 11:07, Art Dent said:

Regarding resistors, the bog-standard 1/4 watt metal metal-film resistors will do just fine - such as these from ebay (£0.99 for 20 / free p&p)

 

 

Thank you so much - just what I needed!

 

I guess I need the 220R resistors from the list?

Or will 200R be okay? 

Edited September 7, 2020 by Sir TophamHatt

[Michael Hodgson]

If you put 16v AC (but some DCC systems are a few volts higher) into a bridge rectifier you'll lose a couple of volts over that and get about 13v DC out of it.

 

You haven't said and I think you implied it, but I hope you do mean LED lighting, not incandescent bulbs. 

A couple of dozen coaches using old fashioned bulbs would be quite a current draw.

 

If you are using capacitor flicker-free system such as Art suggests, definitely not 12v and I wouldn't trust 16v capacitor either on DCC, go for the 25v as he suggest.  Flicker is perfectly reasonable if you're modelling a oil fired tail lamp.

 

The 220R isn't critical and is there to limit recharging rate.  Purpose of the 3K3 is to limit current through the LED, and you might need a different value if you use other LEDs.  You shouldn't have trouble getting either as they are standard values, but I would go higher rather than lower in both cases in case of difficulty.

Edited September 7, 2020 by Michael Hodgson

[Sir TophamHatt]

20 hours ago, Michael Hodgson said:

The 220R isn't critical and is there to limit recharging rate.  

 

So I could potentially skip using that one?

 

Would that potentially trip the power controller as a sudden rush of 8 coaches filling their capacitor at the same time could be seen as a short? But then I guess 1000uF isn't that big - just hope it's big enough for what I'm looking for.

[Michael Hodgson]

Yes it's to stop a sudden inrush, so you do need to limit the current, so you need one in there,   The higher the value the longer it will take to charge when you first switch on, but you probably aren't worried about that (within reason).