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Emmo

H & M Clipper help required

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I have an H & M Clipper unit and pulled out the transformer and rectifier to use in another application, however, I have now decided not to use them and want to put them back, but I clipped the wires in haste and have no idea where they all go. I'm clear where the transformer wires went to but the rectifier has several tags. Could I ask someone on the forum if they own one to take off the cover and take a photograph of the wires on the rectifier please? It would be a great help, thanks.

Martin

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I purchased it the other week to use the transformer to put into my power supply box, then decided not to having found another suitable one. The reason I want to put it back together is to use for test tracks as we mostly have one set up when we have our 3mm Society group meetings.. I use Gaugemaster controllers on my layouts. That said, they do still fetch a fair price at swap meets, exhibitions and the ubiquitous Ebay.

Edited by Emmo

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Please, no more replies of what you would or wouldn't do with them, or what you consider I should use with my layout, that's not what I asked for. Nor did I want an opinion on whether they are safe or not. I asked if someone could open one up and send me a photo of the internal wiring. You are entitled to your opinion but if you are not able to take a picture of one for me to answer my problem, then please, no more replies.

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9 hours ago, WIMorrison said:

The fact that people pay for them doesn’t mean that they are safe or any good.

 

they were acceptable 50 years ago, I wouldn’t even plug one into my house now - far to dangerous. 

 

I have personally had my H&M Duette tested by an electrician and tagged as perfectly safe to be plugged in today. 

 

Back to the original question, https://www.scottpages.net has photos inside various controllers including a Clipper.

 

Cheers
David

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A suggestion if you don't mind is, while you have the case off, consider replacing the rectifier with a silicon diode one. These perform vastly better than the old ones of that era. 

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They do perform better and more reliably. However if you use one you will lose the half wave facility as there is an extra terminal off the H&M rectifier for that supply.  Might be possible to solder up four diodes as a bridge and connect up accordingly. I have a Duette  which I may be able to take some photos of, I think each side is pretty much wired up pretty much the same as a clipper.  I think some later ones did actually use silicon diodes in a bridge.

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11 minutes ago, Titan said:

They do perform better and more reliably. However if you use one you will lose the half wave facility as there is an extra terminal off the H&M rectifier for that supply.  Might be possible to solder up four diodes as a bridge and connect up accordingly. I have a Duette  which I may be able to take some photos of, I think each side is pretty much wired up pretty much the same as a clipper.  I think some later ones did actually use silicon diodes in a bridge.

Surely to do that, you open one side of a bridge rectifier, rather than add a terminal? Probably easier to use 4 separate diodes than a bridge.

 

Something like these.

 

1N5404 3A 400V Diode

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8 hours ago, Titan said:

They do perform better and more reliably. However if you use one you will lose the half wave facility as there is an extra terminal off the H&M rectifier for that supply.  Might be possible to solder up four diodes as a bridge and connect up accordingly. I have a Duette  which I may be able to take some photos of, I think each side is pretty much wired up pretty much the same as a clipper.  I think some later ones did actually use silicon diodes in a bridge.

Ah, I can see the extra terminal as well as the four usual ones - where does that connect with?

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16 hours ago, DavidB-AU said:

 

I have personally had my H&M Duette tested by an electrician and tagged as perfectly safe to be plugged in today. 

 

Back to the original question, https://www.scottpages.net has photos inside various controllers including a Clipper.

 

Cheers
David

The link you sent goes to a page about New Zealand!

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8 hours ago, Titan said:

They do perform better and more reliably. However if you use one you will lose the half wave facility as there is an extra terminal off the H&M rectifier for that supply.  Might be possible to solder up four diodes as a bridge and connect up accordingly. I have a Duette  which I may be able to take some photos of, I think each side is pretty much wired up pretty much the same as a clipper.  I think some later ones did actually use silicon diodes in a bridge.

I have a picture of the inside of the Duette thanks, it is slightly different to the Clipper unfortunately. Thanks for the offer anyway.

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16 hours ago, kevinlms said:

A suggestion if you don't mind is, while you have the case off, consider replacing the rectifier with a silicon diode one. These perform vastly better than the old ones of that era. 

 

Not only do they perform better but they are not likely to kill you. Selenium rectifiers deteriorate over time and when they fail they emit an extremely toxic gas. I wonder if the electrician mentioned above is aware of that?

 

The chances of that happening might be slight but why take the risk when there is an inexpensive alternative?

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8 hours ago, AndyID said:

... Selenium rectifiers deteriorate over time and when they fail they emit an extremely toxic gas. I wonder if the electrician mentioned above is aware of that?

 

The chances of that happening might be slight but why take the risk when there is an inexpensive alternative?

Not that toxic, only oxides of selenium, and it will condense inside the casing if any is formed. If you see a brown-red deposit inside the controller casing refrain from licking it and wash your hands. My Pa began as a valve era electronics hobbyist in the late 1920s, and selenium rectifiers were in 'everything', he's still alive and kicking, and I don't recall any poisoning troubles among the 'Wireless World' crowd.

 

Me now, I went to work for Xerox in their special materials division, and have seen the red smoke many times, and am still here to talk about it. (The original Xerox photocopier technique was dependent on bulk amorphous selenium, and the first automatic photocopier came with a fire extinguisher for deployment against the occasional emerging flaming photocopy. No one died to the best of my knowledge.)

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8 hours ago, AndyID said:

 

Not only do they perform better but they are not likely to kill you. Selenium rectifiers deteriorate over time and when they fail they emit an extremely toxic gas. I wonder if the electrician mentioned above is aware of that?

 

The chances of that happening might be slight but why take the risk when there is an inexpensive alternative?

 

Some 'heritage' electronics discussion groups indicate the smell of burning rectifiers as 'rotten eggs' which would indicate hydrogen selenide (selenium is directly below sulphur in the periodic table - hydrogen sulphide being the more commonly known 'rotten eggs' chemical).

From the CDC (US Centers for Disease Control and Prevention)  https://www.cdc.gov/niosh/idlh/7783075.html

 

Quote

Human data: Although very toxic, no fatalities have been reported, possibly because hydrogen selenide is easily oxidized to red selenium on the surface of mucous membranes of the nose and throat [Friberg et al. 1979]. Concentrations of 1.5 ppm have been found to be intolerable due to eye and nasal irritation [Dudley and Miller 1941].


 

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I shall make a note to not eat an H&M Clipper

 

That was a close call...

 

Richard

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3 hours ago, DavidB-AU said:

This comment says it all really!

 

"There are controllers that have a rheostat instead of an autotransformer, meaning that they change Rs in the circuit above instead of the voltage, V. These are nasty: They slow the train by reducing the control exerted by the controller. Tolerable for slotcars, where the driver must have fast reactions, but bad for trains. The Clipper by H&M was one such, as was the Duette. This is one of the more recent, rheostat-based Duette models, lovely look, bad electrical performance."

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36 minutes ago, kevinlms said:

This comment says it all really!

 

"There are controllers that have a rheostat instead of an autotransformer, meaning that they change Rs in the circuit above instead of the voltage, V. These are nasty: They slow the train by reducing the control exerted by the controller. Tolerable for slotcars, where the driver must have fast reactions, but bad for trains. The Clipper by H&M was one such, as was the Duette. This is one of the more recent, rheostat-based Duette models, lovely look, bad electrical performance."

I do hope that a true autotransfomer is not used.  The definition of an autotransformer is that it has only one winding and therefore no isolation from the mains!

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The H&M units were not autotransformers, they were variable transformers in that the output was taken from a wiper on the secondary windings. IIRC H&M described them as variable transformers.

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8 hours ago, 34theletterbetweenB&D said:

Not that toxic, only oxides of selenium,

 

 

No, not oxides. Hydrogen selenide gas.

 

https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@[email protected]+548

 

"/CASE REPORTS/ A 21 year old female student was exposed to hydrogen selenide gas at least once a week for approximately one year while working in an engineering research laboratory. Chronic diarrhea and abdominal pains developed, and she suddenly developed six dental caries in conjuction with a distinct, garlic odor breath. Clinical tests were normal. After leaving the exposure site, the symptoms disappeared. The major signs of selenium exposure have been described to be a garlicky breath odor, gastrointestinal disorders, metallic taste, upper airway irritation, anosmia, dizziness, clouding of the sensorium, lassitude and fatigue, depression, emotional instability, epigastric pain, belching, watery diarrhea, brittleness and loss of nails, pruritic skin rashes, caries, lethargy, perspiration, generalized tremor, anemia, urticaria, eczema, burning sensation of the skin, and electrolyte imbalances."

 

 

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2 hours ago, AndyID said:

 

No, not oxides. Hydrogen selenide gas.

 

https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@[email protected]+548

 

"/CASE REPORTS/ A 21 year old female student was exposed to hydrogen selenide gas at least once a week for approximately one year...

Yes, the hydride is dangerous. But look at the exposure this student was getting . You are not going to get that from tinkering with the occasional controller. And anyway it will more likely be the oxide which is even lower risk, and no risk at all with a little sensible care.

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22 hours ago, AndyID said:

Not only do they perform better but they are not likely to kill you.

 

For a hobby where we regularly use lead and cadmium based alloys and organic solvents, and indeed selenium compounds (e.g. for metal blackening), I think a sense of proportion is called for.

 

Yes, regular exposure to hydrogen selenide may well be harmful, but we're more likely to encounter the whiff of just one rectifier going bad which might make your eyes water if you're too close. After all, your case study said the symptoms went away when the woman's repeated exposure stopped.

 

With ancient electronics I'd be more worried about being electrocuted through cracked and brittle insulation (David's appears to have passed inspection) 

than being gassed by a dodgy rectifier.

 

Edited by sharris
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Jeez, all I asked for was a photograph! So far I have had people telling me what I should use instead, how dangerous H & M units are, how great and safe H & M units are, and now, a physics lesson and a case report on a 21 year old student!! But alas, still no photo of the damn thing! You will all be pleased to know I have given it to a friend to use the case for something else. This topic is now closed.

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55 minutes ago, Emmo said:

a physics lesson

 

Chemistry actually ;)

 

Glad to hear you won't be using that 50+ year old rectifier. I wouldn't chance it. Others might, but if they want to roll the dice that's up to them.

 

BTW, you don't "own" the topic although you can ask the moderators to lock it.

 

Cheers!

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