Bridge rectifier and polarity 'oops'

[Jasen Betts]

On 2008-10-20, Wayne. <abuse@hotmail.com> wrote:

Wayne. wrote:
I plugged into LTSpice the schematic for a bridge rectifier to test if
it could negotiate the change in DC polarity - which it did.

How much wear will the bridge endure before failing?

Along the train tracks, as it is now it is still in development, I have
segments that have reduced voltage and different polarity depending on
the function of the segment.

At this stage, I am only testing over a 3m section of track.

I read through an article using a 6v dolphin battery and an LED. To
overcome the polarity in the dark, the author used a bridge rectifier.

What I am wondering, can this be relied upon when the train tracks
change polarity through a turn-out loop?

Absolutely,

If the voltage on the tracks changes that may cause brightness changes
in the LED, that depends on how your loco is controlled.

Bye.
Jasen

 

[Eeyore]

Ross Vumbaca wrote:

Hi,

Eeyore wrote:

Sorry, but it's true. Current graduates are almost worse than useless. In
fact I've seen (and rescued) an example where a new graduate nearly
completely wrote off a major project for a major UK plc. I understood the
main problem in under 30 seconds. Bet you never did electronics as a hobby
either. That's where the competent designers come from.

They gave a new graduate so much responsibility that he could write off
a major project? Sounds like the 'major UK plc' was a bit naive too.

A little. Thankfully there was a 'project book' so I could work backwards and
discover where the main mistakes were made. He'd produced reams of convincing
looking equations, all of which were pure garbage or very nearly pure garbage.
Funny thing is, one of his ideas was 'almost right' but he'd got it wrong by
several orders of magnitude.

Needless to say, he was no longer there by the time I arrived.

Graham

 

[Eeyore]

geoffjunkster@gmail.com wrote:

Sorry, but it's true. Current graduates are almost worse than useless. In
fact I've seen (and rescued) an example where a new graduate nearly
completely wrote off a major project for a major UK plc. I understood the
main problem in under 30 seconds. Bet you never did electronics as a hobby
either. That's where the competent designers come from.

Graham

Had a graduate recently apply for a job who could not calculate a
circuit with 1 zener, 1 battery and 1 resistor!

Sadly doesn't surprise me.

I was helping out my nephew with an op-amp problem a little while back. He
finally got the gain equation right with some prompting but then told me he
needed a calculator. I said "use the one on your PC" but he said he needed an
'expression evaluator calculator' ! For something like A = B + ((C+D)/(E-F)) !

I got the answer accurate to 1 decimal place in my head FFS. <sigh>

Now go to Asia and see if they can answer it !

Graham

 

[Eeyore]

Jasen Betts wrote:

On 2008-10-20, Wayne. <abuse@hotmail.com> wrote:
Wayne. wrote:
I plugged into LTSpice the schematic for a bridge rectifier to test if
it could negotiate the change in DC polarity - which it did.

How much wear will the bridge endure before failing?

Along the train tracks, as it is now it is still in development, I have
segments that have reduced voltage and different polarity depending on
the function of the segment.

At this stage, I am only testing over a 3m section of track.

I read through an article using a 6v dolphin battery and an LED. To
overcome the polarity in the dark, the author used a bridge rectifier.

What I am wondering, can this be relied upon when the train tracks
change polarity through a turn-out loop?

Absolutely,

If the voltage on the tracks changes that may cause brightness changes
in the LED, that depends on how your loco is controlled.

And you don't need effing LTSpice to tell you that !

Graham

 

[Eeyore]

Phil Allison wrote:

** You mean there is ANOTHER brand besides PIC ??

LOL !

Graham

 

[Eeyore]

"David L. Jones" wrote:

"Phil Allison" <philalli...@tpg.com.au> wrote:

** You mean there is ANOTHER brand besides PIC ??

Apparently.
He hadn't even heard of PIC.

Guffaw ! What the heck DO they actually do for those 3 years ?

Graham

 

[David L. Jones]

On Oct 20, 7:32 pm, "Wayne." <ab...@hotmail.com> wrote:

Wayne. wrote:
I plugged into LTSpice the schematic for a bridge rectifier to test if
it could negotiate the change in DC polarity - which it did.

How much wear will the bridge endure before failing?

Along the train tracks, as it is now it is still in development, I have
segments that have reduced voltage and different polarity depending on
the function of the segment.

At this stage, I am only testing over a 3m section of track.

I read through an article using a 6v dolphin battery and an LED. To
overcome the polarity in the dark, the author used a bridge rectifier.

What I am wondering, can this be relied upon when the train tracks
change polarity through a turn-out loop?

Oh, and no I am not a student. Just someone who want to do something
fancy with a train set that I am resurrecting after 20 years of sitting
idol.

If you want to do something fancy then go with DCC:
http://en.wikipedia.org/wiki/Digital_Command_Control
Just buy the modules and controllers you need.

Dave.

 

[Wayne.]

David L. Jones wrote:

If you want to do something fancy then go with DCC:
http://en.wikipedia.org/wiki/Digital_Command_Control
Just buy the modules and controllers you need.

Dave.

If my layout was bigger, then DCC is definitely the path I would take.

There was an article in RailBrick e-zine discussing DCC and Lego trains,
plus there is several sites dedicated to or have information about DCC
and similar controls.