bigclive

It's reassuring to know that the old fashioned mercury vapour UVC tubes are still king for high output and long life germicidal use. The UVC tubes are basically a fluorescent tube with no phosphor and a uviol/quartz glass that passes UVC wavelengths. You can buy them off the shelf at aquarium suppliers, noting that they will cause skin damage and arc-eye to humans and animals if they are exposed. I'm not sure about the use of PIR switches to turn these lights off when movement is detected. They could fail and people would be exposed to the running lamp, and if you went into a room with one of the lights and fell asleep it would reactivate. This pandemic has done three major things in UV technology:- Created a new market for existing fluorescent technology. Given the UVC LEDs a much needed bump. (they still fall well short of mercury tubes) Pretty much launched the market for Ushio's 222nm excimer lamps. (A human-safe UVC wavelength.) It's also resulted in lots of ordinary people having dangerous high power UVC lamps in their homes that will eventually be found by people who don't know what they are, and will suffer eye and skin damage. The market for "ice blue" and near-UV LEDs has also benefited from all the fake germicidal lamps being widely sold on eBay and amazon.

The current thing is the 222nm narrow band UVC wavelength that is considered too short to penetrate the outer layer of skin or even the tear film on your eyes. It currently has to be generated by a specialist style of lamp called an excimer lamp that is driven capacitively. The main manufacturers are Ushio. At the moment it's being used in medical environments and is basically being tested on hospital staff right now! With regards to the fogging. Research into air sterilisation was done a long time ago, where the air in wards was hazed lightly with glycol just like a fog machine hazes the air. It was claimed that it had a dramatic effect in reducing cross infection by presumably having a moisture-hungry curtain of sticky droplets in the air. Unfortunately, without modern testing on coronavirus it could be claimed to achieve those results. The nightclub industry has been testing long term public exposure to airborne glycol for several decades though, with no obvious health effects.

I used to get service calls to fix the aftermath of fights between strong winches and thick coagulated dirt and grease that was the result of well-meaning, but wrong track maintenance. Grease is not your friend on the old track and bobbin system

I usually try to cut back to clean copper if possible, but you may be able to scrape the surface tarnish off if it's a low current circuit. Flux might help, but my own experience with deep corrosion is that it results in weak solder joints.

That's thinner than expected - more like a traditional smoke machine tube, but for a short tube they'll have had to go with small diameter and very thin wall to keep the resistance high enough to allow a sensible current.

I wonder what voltage drop there is across the tube. 30A is lower than I expected.

Whoa! It's Alive! This thread has been resurrected from the dead. But it's good, because it's a reminder of how modern products like addressable festoon have made life a lot easier than lots of dimmers and wires. The downside being that if it's cheap and easy then the novelty is gone because anyone can do it. And sometimes the new products introduce their own technical issues.

The stainless steel makes sense as it has a relatively high resistance and makes direct heating more practical. That also applies to the thinner wall size. The cleaning cycle suggests that it might be trying to dry out, dislodge and then blow out any residue as dust. It suggests it might pay for a hired unit to be run through several cleaning cycles occasionally, to try and compensate for the complete lack of proper shutdown that usually happens on a hire. Clever that they do one at startup to guarantee a self cleaning cycle.

Brass and copper are quite conductive, so it must be relying on very high current at low voltage for such a short length. That makes even a slightly oxidised connection an issue. What would you guess is the rough diameter of the tube?

I can guess that the shutdown is simply stopping the fluid pump and keeping the air one running for a while to try and get any residual fluid through. These things never get shutdown properly in an event environment. Are the pipes in the direct heating system made of stainless steel?

From the smell of the liquid I think most of the short-heater and air pump style hazers work with glycerol based liquid. Between the use of glycerol and occasional inadvertent use of oil based haze fluid by well meaning crew it does mean that the heater pipes should be considered a disposable item. I've never really had a chance to explore a neutron hazer. Is it the type that uses the pipe itself as a heater by passing high current at low voltage through it? If it is, then theoretically the ultimate service for these units would be to replace the tube with a new one if it was clogged and make sure the electrical connections onto the pipe were clean and solid, as any resistance at all would impact the current flow and heating ability greatly. The pipe would also have to be the correct gauge and material for optimum results. The liquid and air pump are also cheap and disposable items in my book.

I've added a series resistor with a similar microphone. I initially added a small resistor substitution box in line, and then recorded me saying each selected resistor value as I incremented it to find the optimum result.

What's the base hardware required to run OBS properly these days? I've been using a Chromebook for so long that I'm out of touch with box-on-the-desk computers.

The resultant colour will depend strongly on the spectral peaks emitted by the LEDs. It may be worth masking a light off with cardboard with a slot and trying some swatch gels over it to see the throughput and resultant colour.

The words sanitary and marquee don't really go together.

I get the feeling that everything is being blown out of proportion regarding this virus. The media hype may actually be causing more deaths due to the extra stress and fear it's inducing in people diminishing their body's ability to self defend. A Facebook friend got the virus after travelling and said it was a brief cough and fever and that's it. He's now enjoying a self-isolation holiday. Without media hysteria this could have been just another seasonal flu bug and nobody would have been any the wiser. By the end of the hype I bet less people have died than the typical 100 to 10,000 that flu claims in the UK each year. So that just leaves the question. Who's benefiting from the scaremongering and how? The medical industry will be doing well and the collapsing of the stock market will make it very rich pickings as things gradually return to normal.

Ouch. Is there a more robust diode with a decent reverse voltage in each chain? I mean, I guess it doesn't matter but makes me anxious. The way modern strings are configured is in large parallel sections of inverse parallel LEDs that are then wired in a series group to make up the required string voltage. Usually ten sets for around 30V, but sometimes 8 sets for 24V. That means that the max reverse voltage across any LED is capped to around 3V by the alternate polarity LEDs in the string. Controlling these strings is a nuisance as the supplied controllers are usually current limiting and swap the polarity for "multi-channel" flashing effects. When static they are actually reversing polarity at a fairly high speed. I'd recommend avoiding them where proper control is required. Even with just static on you'll probably have to add an extra resistive load to give a dimmer something it can work with. The electronic supplies should only be switched and not dimmed.

I've never seen a battery tester that reliably indicates the remaining charge in a NiMh rechargeable cell. The voltage is not a good indication of that, unlike with rechargeable lithium cells. The testers that put a load on a non rechargeable cell also just give a vague state as opposed to a specific value.

Whatever you use, make sure it's serviceable. Water will always find a way in, and LEDs don't always last as long as expected.

It's been around for a while and may even have appeared on kickstarter. One manifestation has a "key" that goes into the earth receptacle to open the safety shutters.

The heated yoga studios I've seen used infrared heaters. Are they really doing it in sauna environments? That sounds like a big issue for more than just a headset.

Make sure that they're not on an electronically controlled power source (like a dimmer) and check the voltage at one to make sure it's not well off spec if there's a floating neutral. (The voltage would fluctuate with other loads in the same area.) Note that if there is a miswired supply it's wise to treat the whole system as a safety risk.

Something like this? https://www.ebay.co.uk/itm/252016221405 (Noting that a good approach is to divide a system into lots of smaller decoders and power supplies.)

I'm getting quite a lot of creepy comments on my video from defiant DJ experts announcing that the connector on the back of the dodgy smoke machine is not called an "XLR". It's actually called a DMX connector apparently. My corrections have been met with defiance or silence. I've had to delete some of the comments because they could encourage people to plug DMX leads in.

Can I suggest a traditional apprenticeship in a specific trade first. Skills like Electrician, painter, carpenter, welder/fabricator etc will give the person a solid career and then let them enter the event/theatre industry with a relevant trade skill that they can fall back on later when they realise that the industry has more applicants than jobs and is rather exploitative.