Model Railway Forum

Go Back   Model Railway Forum > Model Railway Construction > Wiring & Electronics > Other


Reply
 
Thread Tools Display Modes
Old 26-10-2017, 08:31 PM   #11
Chuffchuff
Member
 

Join Date: Nov 2016
Posts: 54
Chuffchuff is on a distinguished road
Default

Many thanks for your replies, I now have a host of directions I can tinker with.

A couple of thoughts;

Where does the term Buck come from with regard to DC converters ?

Fashbang queried my thoughts on amps. In my simple mind I was thinking along the path of "Watt goes into a converter would be watt would come out". ( if you will excuse the awful pun)

Which brings to mind the old Goons Joke " Watt, WAtt, WATT ! I'm feeling bright today! ". Somehow ""Lumen, Lumen, Lumen"". Doesn't have the same connotation.

Thanks again.
Chuffchuff is offline   Reply With Quote
Old 27-10-2017, 01:20 AM   #12
Suzie
Senior Member
 
Suzie's Avatar
 

Join Date: Sep 2013
Posts: 387
Suzie is on a distinguished road
Default

'Boost' is increasing the voltage where the input voltage is always below the output voltage, while 'Buck' is reducing the voltage where the input voltage is always greater then the output voltage. Most switching converters are either one or the other, but sometimes you get 'Buck/Boost' converters which can do both for example getting regulated 12V from a car battery which can vary from 10V-15V depending on battery condition.
Suzie is offline   Reply With Quote
Old 27-10-2017, 10:18 AM   #13
Footplate1947
Eternal Optimist
 

Join Date: Mar 2015
Location: Cumbria and Scotish boarder.
Posts: 1,887
Footplate1947 is on a distinguished road
Default

Quote:
Originally Posted by Chuffchuff View Post
I would be grateful for thoughts / advice on the following;

In my bits box, I have a couple old metal cased scalectrix 12v 2.5 amp DC power supplies. They both work ok, give about 13v on no load, so should stabilise to 12v in use. Generally in a clean and tidy condition.

In the grand plan, I propose to use them for led lighting and was thinking of using a DC - DC converter to output to 5 volts for all led circuits.

My thought process is that the lower voltage would be better to run the LEDs, and the output current would higher so I could run more LEDs.

Very roughly 12v x 2.5 amps = 30 watts. If I convert to 5 volt I should get 5 amps or so allowing for losses.

Does the idea have merit, ?
Or just tinkering for the sake of it ?.
Or could I light a model city with 12v and still have power for village ;-) or using a DC DC converter to stabilise the output from the power supply at 12v in case the old power supplies have a ripple voltage ?
or maybe just use a 3 amp rectifier to smooth the voltage ?

Rgds
What does Buck mean...........Means it Bucks the voltage. Think of the old saying Bucks the system. It reacts against the voltage...............John
__________________
I may be wrong as I very often am. John

Last edited by Footplate1947; 27-10-2017 at 10:20 AM. Reason: adding text
Footplate1947 is offline   Reply With Quote
Old 30-10-2017, 03:08 PM   #14
Footplate1947
Eternal Optimist
 

Join Date: Mar 2015
Location: Cumbria and Scotish boarder.
Posts: 1,887
Footplate1947 is on a distinguished road
Default

Some body asked what does Buck mean? I answered it, but now cant find the question........O well...............
__________________
I may be wrong as I very often am. John
Footplate1947 is offline   Reply With Quote
Old 30-10-2017, 03:50 PM   #15
Flashbang
Administrator
 
Flashbang's Avatar
 

Join Date: Jul 2009
Location: SE UK
Posts: 8,255
Flashbang will become famous soon enough
Default

Try post #11 above third paragraph?
__________________
Broken? It was working when I left it!
Flashbang is offline   Reply With Quote
Old 30-10-2017, 03:52 PM   #16
Footplate1947
Eternal Optimist
 

Join Date: Mar 2015
Location: Cumbria and Scotish boarder.
Posts: 1,887
Footplate1947 is on a distinguished road
Default

Thanks FB must find those glasses. John
__________________
I may be wrong as I very often am. John
Footplate1947 is offline   Reply With Quote
Reply

Bookmarks



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT +1. The time now is 02:59 AM.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.