Risk Assessment

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Martin,

I think Mark's point was that the cheapest of the cheap may only use half-wave rectification.

MichaelG.

Yes Michael, I have some that simply have a single led chip running from a resistor - the resistor tends to burn out which is how I know what was in them.

You might cram a switch mode psu in a gu10 sized bulb but I have my doubts you can get one into a g9 format, open to being shown one and proven wrong mind.

Mark

OK so I was being a little tongue in cheek.

Seriously though:-

All my designs for led drivers operate at 600kHz plus for the current regulator switching frequency and I generally pulse width modulate at between 1 and 2kHz for dimming. This is at least an order of magnitude faster than biological processes so the cells don't respond to the flashes.

On a slightly different line I don't see why fibre-optics should not be used to effect for a milling light. I have used them for getting photons onto fly brains with the light sources (LEDs) remote from the cells to eliminate heating effects. In that particular instance we needed about 10mW/square mm which is a lot brighter than you want to stare at in order to oxidize stain in fly brains for neural imaging.

regards Martin

I suppose that involves using a fly-cutter?

Joking apart that's really interesting. What sort of microscope and stain is used?

Ta,

Dave

I think that was done on one of the confocals using florescence although I could be wrong. I didn't get involved in the imaging side on that occasion. Regarding Fly-cutters they do have to dissect the brains out of the fly. We are talking Drosophila Melanogastor (Fruit flies) rather than great big Bluebottles.

Martin

My wife bought me a gel wrest and it cured RSI problems that had my arm feeling like it was freezing.

That said I spend too much time sitting down at home these days, but after getting back ache I invested in a cheap 8 hour design and it's much better*.

Neil

*When I was a 'boss' I got rid of my leather covered executive chair and used an ordinary typists chair. We bought one staff member one of those strange kneeler on wheels things. It was very odd to use and I worried about putting my knees out getting off it!

Roll your eyes when looking a many LED type lamps and you will see after images that show many are driven at much lower frequencies from car sidelights to traffic lights.

Neil

So..frankenstein getting up to much these days?

Michael W

Thanks Martin, good stuff. Drosophila brings back some memories that I'd completely forgotten. It's 1970 and there are no flies on me, ho ho.

There was a "types of microscope" question on "Only Connect" in the week that I completely failed to get. As I had to look up confocal too I'm obviously horribly out of date.

Regards,

Dave

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Perfectly fine, provided you can pick-up a suitably sized bundle [or ringlight] at an affordable price.

Retail prices for Schott items are eye-watering for the hobbyist. **LINK**

http://www.astroshop.eu/microscopy/microscopy-accessories/lighting/23_60_40/m,Schott/a,Mikroskope.Allgemein.Serie=KL-1500-1600-2500

MichaelG.

The microscope type fibre optic lighting can be picked up more cheaply 2nd hand. I sold one where the fibre optic cable split into 2 which might be a better option than a ring light for general use in other areas.

There are also some pure ring of LED's ring lights about. I tried one for macro photography - hopeless compared with flash.

I've been wondering about certain LED lamps that are usually attached to bikes, even motor bikes but a lot of them have plain glass at the front. I know from my headlamp and a couple of Ikea lights that they need an odd shaped lens on the front for an even beam. A couple of the heads on the Janjo range could be positioned pretty close to a milling cutter if needed. They are all on flexi-stems. As the distances could be fairly short it would make up for the light output levels. Not so good on a lathe as more distance is a good idea.

John

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I am not an electrician myself, but I do visit building sites, where I wear the company standard PPE, which is for electricians. We all have gloves with open ended thumb and forefinger, specifically to address that problem. The sites I visit are all major office developments, with large safety budgets and many safety elves. So it can be done. Sorry, I don't know the exact rules by which this is allowed. So can't say if there is some key difference in situation which would not allow the same.

If it were that simple, the arguement is the gloves are to protect the hands and cutting the fingers off is loosing the protection, we work in Hospitals, research facilities and universities which I assume is the same as offices etc, the only difference I can see is wiring buildings have larger wires where I work with considerably smaller wiring and with gloves on you loose the feeling of the wires.

Martin P

Fans of the IKEA Jansjo clip-on LED spotlight might like to review their 'risk assessment'

My wife clipped her lamp onto the edge of the ironing board ... and the clip failed rather spectacularly under the pressure applied by its own spring.

No harm was done, but ... if it had been clamped over a lathe or mill, things might have gone badly.

MichaelG.

Good old D Mel....

Time flies like an arrow. ...

Fruit flies like a Banana

Pink?

In The Workshop?

I Think Not Old Chap!

I found that the end of the "bendy" was threaded 8x1 mm. I don't have a suitable tap but 5/16" x 26 which I do have is close enough. Married to a magnet from an old hard disk works pretty well in the workshop for a machine light. I'd be confident enough in my masculinity to have a pink one

Rod

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Isn't it typical ?

I post a safety warning, and no-one responds for more than three weeks

... and when somebody does comment, it's 'comedy'.

MichaelG.