Next question - DCC

"Greg Procter" wrote

Should be cost-effective if you use a credit card or PayPal.

John.

Reply to
John Turner
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"simon" wrote

Not if you've already got a CDU from the days of using conventional points operation.

John.

Reply to
John Turner

Can you use a conventional CDU on a DCC operated point ?

Cheers, Simon

Reply to
simon

From the middle of the North West Leicestershire and Southh Derbyshire coalfields - I am happy to say closing the coal mines was one of her major achievements. Plus you lot were rotten to the south leics lads.

Cheers, Simon

Reply to
simon

"simon" wrote

Only to the scabs. ;-)

John.

Reply to
John Turner

"simon" wrote

I don't have the foggiest idea, seeing as I still use conventional operation for points.

John.

Reply to
John Turner

It's a damn expensive way to stop the wrong loco from running!

Reply to
Greg Procter

Hell no, I read the occasional MR article and railway electronics books. I looked at CDU design and just asked myself why they are like that. It seemed to me that a PC board, transistors and associated parts were semi-redundant so I cut the circuit down to the minimum number of parts. At that point it did what the complex one did but took circa 0.5 seconds to recharge, quicker than I could get my finger from one push button to the next. Then I figured that my budget for the "real" CDU would buy me a whole bunch of my basic CDUs and as I'm into route setting the lower current of one CDU per point motor made more sense.

Me too - not enough but I step up my standard with each new problem/situation.

Soldering and I generally get on quite well. :-)

Reply to
Greg Procter

She's someone you all need to remember every election so you don't elect another one!

Greg.P.

Reply to
Greg Procter

Credit cards work very well - the bank charges a percentage but you have to be buying a ship or something before that charge matches the cost of a bank draft. Paypal and I don't seem to get on - someone played in my account. We used to have "British Postal Orders" we could buy from the post office to send money to starving relatives or model shops in Britain until you joined the EU.

Regards, Greg.P.

Reply to
Greg Procter

The accessory decoder transistors have to switch the current your point motor is drawing, so a conventional CDU isn't advisable - they will probably work fine until the smoke gets out.

Greg.P.

Reply to
Greg Procter

The correct answer is that the accessory decoders switch using transistors/thyristors/Triacs/... with a finite current limit. They are fine until the smoke gets out.

Regards, Greg.P.

Reply to
Greg Procter

The current is limited by the impedance of the point motor, regardless of where the current is sourced from. The magnitude of the current depends upon the voltage at the source. If the output voltage of the fully charged CDU is within the spec of the accessory decoder then it will be perfectly safe. In fact, a CDU will be safer than an equivalent voltage normal power supply since the CDU voltage (and hence current) drop rapidly once the switch is closed.

MBQ

Reply to
manatbandq

}John Turner wrote: }> }> "simon" wrote }> }> > Heck no, none of them come anywhere close to the magificent Mrs Thatcher. }> }> How dare you mention that witches name in a forum which reaches the areas in }> the north of England where coal used to be mined? } }She's someone you all need to remember every election so you don't elect }another one!

Blair is "whiter than white" is he ? As promised to the people who elected him ?

He is also a liar - believe the Case he made for war. LIAR.

Back on topic

Where can I get 2mm scale red brick paper for a massive Victorian 4 lane loco shed that 1in N gauge scale is 120 mm by 180mm :)

It is vast :)

{R}

Reply to
{R}

In that case a CDU drawing it's supply from the DCC voltage would be considerably _less_ effective than no CDU! OTOH a CDU drawing it's current from a separate transformer would reach circa 1.4 times the rated transformer voltage. Active electronics components usually fail instantly when subjected to excessive voltages.

Greg.P.

Reply to
Greg Procter

He did warn you! His name is B liar!

I don't know, surely some of the card kit makers offere it?

Nowadays I use embossed styrene sheet for my HO scenes, because although printed card often better reproduces the colours of brick it doesn't have the relief and it fades with time. If you're going to build something massive it will take you some time so you'll want it to last.

Greg.P.

Reply to
Greg Procter

Download it from Scalescenes.

And start a new thread next time.

MBQ

Reply to
manatbandq

Running (solenoid) point motors from the DCC supply _without_ a CDU is forbidden in my book.

The point you may be missing is that many DCC accessory decoders are designed to use external power supplies for switching solenoid point motors, rather than the DCC supply, for this very reason. The Lenz LS100/110, for example, can use 18V AC or 25V DC which are higher than the DCC track voltage in most cases. If the CDU voltage is in spec, it's perfectly safe.

MBQ

Reply to
manatbandq

That's fine by me. However, you're running a square wave voltage through a (bridge) rectifier and several transistors in series so you're dropping the initial impulse voltage by at least 3 volts from the DCC bus voltage and down towards zero volts ouput.

That depends on the accessory decoder design and componentry. Two common voltage ratings for electronics components are 25 volts and 35 volts. The 25 volt ones are considerably cheaper that the 35 volt ones so they get used. 18v AC is 25.4 volts (peak) and an 18 volt trafo will deliver considerably more at low load (circa 120%). There could easily be 30 volts peak on the capacitor, which is pushing one's luck with 25v components.

Regards, Greg.P.

Reply to
Greg Procter

Probably orchestrated by a 'dealer' who sees the possiblity of making a quick buck by selling premium priced 'DCC ready points' over the internet which will turn out to be bog-standard Peco points. Or am I just being cynical in my old age?

Alan

Reply to
Alan P Dawes

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