H & M Clipper help required

[meil]

On 22/09/2019 at 12:30, melmerby said:

Especially the edible ones!

All Fungi are edible - it's just that some are only edible once.

Edited September 27, 2019 by meil

[sharris]

On 22/09/2019 at 08:44, PatB said:

ISTR a photo of a Hornby Metropolitan electric and it's controller which indicated that the "resistor" took the form of a mains lamp bulb next to the speed control handle. 

 

The Hornby loco, made in 1925, required 110V on the track - still lethal! Apparently questions were asked in Parliament and the track voltage was reduced in later models to something safer 

 

https://www.brightontoymuseum.co.uk/index/Metropolitan_underground_locomotive,_110V_(Hornby)

 

 

[kevinlms]

15 minutes ago, sharris said:

 

The Hornby loco, made in 1925, required 110V on the track - still lethal! Apparently questions were asked in Parliament and the track voltage was reduced in later models to something safer 

 

https://www.brightontoymuseum.co.uk/index/Metropolitan_underground_locomotive,_110V_(Hornby)

 

 

I see that a suitable lamp wasn't included in the box. So how many didn't work on the first day, without stealing a lamp from elsewhere?

[PatB]

23 minutes ago, kevinlms said:

I see that a suitable lamp wasn't included in the box. So how many didn't work on the first day, without stealing a lamp from elsewhere?

Probably not too much of a disadvantage, as you could use the one removed to allow the set to be plugged into the house light fitting.

[DCB]

 I was unaware that early Hornby Tinplate was 110 volts, I assumed they were 20 volts. I wasn't suggesting anyone tried mains voltage, just pointing out what they used to do.  Our house still has the original electrical sockets  from when mains came to the village post WW2, they were disconnected in 1962 but we haven't got round to removing them.  One bedroom and the landing had sockets upstairs and the kitchen and one reception room downstairs, from 3 bedrooms and two reception rooms downstairs.  All apart from the Kitchen were the small 5 amp (possibly 2 amp type.   We still have a box of fittings or doublers which allow a lead to be connected to the light fitting  as well as a bulb, really handy (for odd bits of brass not to actually use)  The House was changed to 13 Amp square pin in 1962 and rewired again since

I am rather fed up with the insults about LEDs.   Other people also suggest alternative approaches to powering LEDs.  For instance see.     https://www.instructables.com/id/Using-AC-with-LEDs-Part-1/       

Edited September 28, 2019 by DavidCBroad

[Crosland]

15 minutes ago, DavidCBroad said:

Other people also suggest alternative approaches to powering LEDs. For instance see

 https://www.instructables.com/id/Using-AC-with-LEDs-Part-1/       

 

Finding other idiots on the internet does not promote your cause.

 

If you think what they are doing is OK, explain the theory to the rest of us.

 

[melmerby]

30 minutes ago, DavidCBroad said:

   Other people also suggest alternative approaches to powering LEDs.  For instance see.     https://www.instructables.com/id/Using-AC-with-LEDs-Part-1/       

Really? You think that guy knows what he's talking about?

13 minutes ago, Crosland said:

 

Finding other idiots on the internet does not promote your cause.

 

If you think what they are doing is OK, explain the theory to the rest of us.

 

Exactly so, comes under the 50 million flies can't be wrong bit.

[kevinlms]

33 minutes ago, DavidCBroad said:

 I was unaware that early Hornby Tinplate was 110 volts, I assumed they were 20 volts. I wasn't suggesting anyone tried mains voltage, just pointing out what they used to do.  Our house still has the original electrical sockets  from when mains came to the village post WW2, they were disconnected in 1962 but we haven't got round to removing them.  One bedroom and the landing had sockets upstairs and the kitchen and one reception room downstairs, from 3 bedrooms and two reception rooms downstairs.  All apart from the Kitchen were the small 5 amp (possibly 2 amp type.   We still have a box of fittings or doublers which allow a lead to be connected to the light fitting  as well as a bulb, really handy (for odd bits of brass not to actually use)  The House was changed to 13 Amp square pin in 1962 and rewired again since

I am rather fed up with the insults about LEDs.   Other people also suggest alternative approaches to powering LEDs.  For instance see.     https://www.instructables.com/id/Using-AC-with-LEDs-Part-1/       

 

I was unaware that transformers existed in anything but an A.C. format. But I'm prepared for enlightenment!

 

The first line gets the article off to a bad start!

 

"Recently I came across a high quality transformer selling for under $1.00. The reason they were so inexpensive was the fact that their output was AC only"

[SHMD]

...shakes head...….

 

 

[Crosland]

2 minutes ago, kevinlms said:

 

I was unaware that transformers existed in anything but an A.C. format. But I'm prepared for enlightenment!

 

The first line gets the article off to a bad start!

 

"Recently I came across a high quality transformer selling for under $1.00. The reason they were so inexpensive was the fact that their output was AC only"

 

Left-pondians tend to refer to anything that plugs into the mains as a "transformer", regardless of whether it's AC, DC regulated, unregulated, ...

 

We know that a transformer is a heavy lump of iron

 

[melmerby]

24 minutes ago, Crosland said:

 

Left-pondians tend to refer to anything that plugs into the mains as a "transformer", regardless of whether it's AC, DC regulated, unregulated, ...

 

We know that a transformer is a heavy lump of iron

 

I thought it was a car that changed into a robot............

[dhjgreen]

51 minutes ago, Crosland said:

 

Left-pondians tend to refer to anything that plugs into the mains as a "transformer", regardless of whether it's AC, DC regulated, unregulated, ...

 

We know that a transformer is a heavy lump of iron

 

So if it uses ferrite it is not a transformer 

[WIMorrison]

53 minutes ago, Crosland said:

 

Left-pondians tend to refer to anything that plugs into the mains as a "transformer", regardless of whether it's AC, DC regulated, unregulated, ...

 

We know that a transformer is a heavy lump of iron

 

I find that they are very useful to hold down track when waiting for the copydex to set

[Dave John]

Well there used to be something called a DCCT, or direct current current transformer. 

 

Its purpose was not power transmission, it was an instrumentation device used to measure a DC current without being electrically connected to the circuit being measured. Basically a transformer magnetically coupled to the DC conductor.  Feed AC into the primary of the DCCT, the AC current in the secondary is altered by the magnetic flux in the DC conductor saturating the core of the DCCT. Load and rectify the AC output of the secondary and that will give a DC output proportional to the DC current to be measured. 

 

You are unlikely to come across one these days, tends to be done with a hall effect sensor now. 

 

My memory fades a bit, but someone dig out the circuit diagram for a class 50. The real ones, not the model. 

 

 

 

 

[kevinlms]

1 hour ago, Crosland said:

 

Finding other idiots on the internet does not promote your cause.

 

If you think what they are doing is OK, explain the theory to the rest of us.

 

Alternatively, David could provide us with a link to a reputable source that dispenses with the recommendation of using resistors, something like an LED manufacturers datasheet, would do nicely.

[sharris]

2 hours ago, DavidCBroad said:

Other people also suggest alternative approaches to powering LEDs.  For instance see.     https://www.instructables.com/id/Using-AC-with-LEDs-Part-1/       

 

An approach that seems to involve finding exactly the right number of similar LEDs to match the transformer (or adding in an LED of a different colour if you can't) - seems a rather restrictive way of going about things when 1 resistor can do the job more cheaply than excess LEDs.

[kevinlms]

41 minutes ago, sharris said:

 

An approach that seems to involve finding exactly the right number of similar LEDs to match the transformer (or adding in an LED of a different colour if you can't) - seems a rather restrictive way of going about things when 1 resistor can do the job more cheaply than excess LEDs.

Yes, that's what strikes me as odd. Trying to save the cost of a resistor, which is one of the cheapest electronic devices available and if you choose the correct wattage, will last indefinitely.

[melmerby]

To me  a transformer is something that goes inside a power (supply) unit.

On it's own, without connectors, plugs, wire, case etc. it's pretty useless, except as Ian says for holding down track until the adhesive dries!

 

[melmerby]

2 hours ago, sharris said:

 

An approach that seems to involve finding exactly the right number of similar LEDs to match the transformer (or adding in an LED of a different colour if you can't) - seems a rather restrictive way of going about things when 1 resistor can do the job more cheaply than excess LEDs.

He bemoans the use of diodes to rectify the AC as it "wastes volts and creates heat!" What a skewed way of looking at it.

He also doesn't know, doing it his way, if the LEDs are operating outside their recommended limits, on the peaks of the waveform.

If the mains input increased by say 5% (not unkown) then the LEDs could be suffering a considerable overload for part of the cycle, leading to shortened life.

Using a resistor would swamp the effect of this increase and keep the LED in safe operating range.

 

Edited September 28, 2019 by melmerby

[sharris]

One of the things I find annoying about some of these unconventional methods is they can end up being 'works for me' approaches. 

 

Fine, you can power exactly 7 (or however many) of your LEDs from your power supply without a resistor or reverse-voltage protection, but when it comes to reproducibility, what if I buy some random LEDs from an exhibition stand that have a slightly different Vf (or they come from a grab-bin with various  Vfs - I don't want to spend my time characterising every component I buy)? - LED datasheets will specify a Vf range anyway, the knee may be in a slightly different place for devices of the same type.

 

A 'works for me' approach might not work well for someone else - I get annoyed too when a construction article says '...and I used this widget from 1957 that I found at the bottom of my toolbox'.

[AndyID]

4 hours ago, Crosland said:

 

Left-pondians tend to refer to anything that plugs into the mains as a "transformer", regardless of whether it's AC, DC regulated, unregulated, ...

 

 

Oi! I resemble that remark.

[JohnDMJ]

On 14/09/2019 at 11:43, RedgateModels said:

Here you go, hope this helps

 

 

 

Looks pretty good until you see the asbestos pad top left and can't easily pick out an earth connection.

 

I would decline to PAT certify any H&M controller!

[maico]

Is the resistor board ceramic or asbestos ? If you enlarge the photo here it appears to be fraying 

https://dublonutz.blogspot.com/2014/04/new-layout-control-panel-inside-duette.html

[Crosland]

3 hours ago, sharris said:

A 'works for me' approach might not work well for someone else - I get annoyed too when a construction article says '...and I used this widget from 1957 that I found at the bottom of my toolbox'.

 

The real problem is those employing the "works for me" solution without understanding why it works from them.

 

Much like using a coin cell or low voltage wall wart to drive LEDs with no current limit resistor.

[melmerby]

1 hour ago, maico said:

Is the resistor board ceramic or asbestos ? If you enlarge the photo here it appears to be fraying 

https://dublonutz.blogspot.com/2014/04/new-layout-control-panel-inside-duette.html

Whoever did that re-used the selenium rectifiers

 

Madness.