pmiller056

@Owain - at present, no. The fluorescent fittings are open-tube ones (no diffusers or reflectors) attached directly to the undersides of the open roof trusses (for minimum cost worklighting). They throw light everywhere, so in practice bank switching won't acheive much. I'm beginning to think that any money that could be spent improving the worklights probably would be better spent on improving the houselights, which is what people want to use.

Your eye hurting afterwards is probably the same as 'welding flash' eye irritation due to the exposure to really bright light. Hopefully it will go away of its own accord in a day or two. A class 4 laser is very dangerous and can instantly cause permanent damage to eyes, skin and more if used incorrectly. Everyone in the room/space was put a risk of permanent harm by the way the laser systems were used. If I was in your situation, I'd phone HSE and report the laser system operator for installing and using a system that put the public at risk of harm. Similarly, if the venue is a professionally run business, make your concerns known to the company director directly responsible for health and safety. Go for an eye test. As part of a normal eye test, the optician will look at or photograph your retina anyway. Explain what has happened and they should have a more detailed look for laser related damage. Sadly most opticians do know what laser damage looks like. You've had a close call. Read the PLASA and HSE guidance on the safe use of laser systems in entertainment and if you find yourself in a similar situation, leave. Stay healthy.

Thank you all for your helpful comments and suggestions. The working and house lights illuminate the same useable space and are available to all auditorium users. For logistical and practical reasons it is not practical to restrict access to the inefficient house lights for specific users. The auditorium has a pitched ceiling which is the underside of the roof and is painted black, so uplighting as suggested by @adam2 is not a sensible option. Our treasurer is well clued up on the cost of heating, lighting, cleaning, maintaining and generally running different parts of our building - I'll let him/her tell the managment committee how much to charge our hirers. Energy savings will most likely end up in the capital account to pay for future 'big ticket' refurbishments and upgrades. The fluorescent working lights have a higher colour temperature than the house lights which makes them look harsh and industrial in comparison. They are relatively new (<10 yrs), so they have HF electronic ballasts, are flicker free and start 'nicely'. We have noted that different users do set different brightness levels to suit their needs when using the dimmable lighting, so it is a feature that hirers want to use. If a good dimmable houselights system is installed and the operating costs are similar then I would expect the fluorescent working lights to become disused and eventually removed. The GDS systems noted are very nice but well outwith our budget range. The Artistic Licence product mentioned by @A.Russell is interesting because it appears to work nicely with well-chosen commercially available 'normal' LED lamps. A benefit of this system is that it can re-use most of the existing infrastructure and wiring which will significantly reduce installation costs. We are able to acheive a very dark blackout, so from comments above, low-end 'snap on' is something that needs to be well controlled in any upgraded system. Another benefit of the AL product highlighted is that it is natively a 4 channel system, so it would be a 'drop in' replacement for our existing bank-switching arrangement. Looking at @Tomo's suggestion, the houselight system is available 25/7/365, so I'd be inclined to use 'normal' household/industrial lamps. In the first instance I'm not sure about the long-term survival of leaving theatre/entertainment COB PAR fixtures powered continuously. Trying to get a compatible like-for like replacement for any failed COB PAR fixture after installation may be difficult. Changing a group of 'normal' lamps after failure will be easier and cheaper when LED lamps do fail, despite the manufacturer's promises.... Thank you again.

A question on behalf of a local community theatre... The auditorium gets used for community hires. The tiered theatre seating is usually stored rolled away, leaving a useful flat floor space of around 5m x 15m for dance, drama classes and similar uses. Most hirers regularly use the dimmable house lights 'because it looks nicer' instead of the fluorescent working lights. This lighting is installed at a height of 5 to 6m above the floor. 1.7kW of dimmable halogen downlights costs a lot of money to run. The halogen lamps are supplied from a common 2.5kW thyristor dimmer and are switchable in 3 banks to cater for different uses of the space. Are there any sensible dimmable LED options to replace the existing lighting to reduce running costs? I'm aware of the limitations of some dimmable LED systems at low (<20%) brightness levels. Depending on chosen solution, the existing thyristor dimmer does not need to be retained. Needless to say, because it is a self-funded community space, the installed cost of any replacement is a major consideration. The pay-back time based on energy savings will be a big influence on any chosen solution. Thank you.

Your students are there to learn. It will be much better to teach them how to use widely used equipment, such as a scaff tower, competently and safely as part of their education. Your students are much more likely to be asked to use a scaff tower in later real life, particularly if not working within a standard theatre environment. Erecting and dismantling a scaff tower is also a good practical lesson in teamwork that cannot be taught in a classroom or over a video link.

Assuming you are buying genuine cells, do check the cell datasheet if you can. Most people focus soley on the Ah rating. You also need to consider the intended discharge use (and other factors, but that's most important). Cells intended for power tool batteries will have a lower Ah rating, but will survive high current discharge duty well. A USB power bank has a longer term, lower current discharge duty, so these tend to use higher Ah rated cells better suited for this usage.

Replace the swivel castors on one side with fixed ones. Two fixed and two swivel castors underneath means that you can steer your trolley.

To follow on from Adam2's comment, even if we can get the relevant lamps, where are we going to get the correct ballasts and control gear from? Again, mass production is essential to make manufacture viable. A local electrical wholesaler catering mostly to light industrial and smaller users has given up selling complete fluorescent lamp fittings and replacement internal parts such as ballasts because of lack of demand. They still sell lamps and starters, but demand is rapidly slowing as people make the change to LED at lamp-change time for efficiency reasons.

The Crown amplifiers I mentioned were actually Techron's. Techron specialises in big audio frequency power amplifiers for industrial and research applications. At the time we bought them (late 90's?), Techron was a subsidiary of Crown and fundamentally they were re-branded Crown Amplifiers. The LF frequency response may have been modified from the Crown design to go all the way to DC.

I was involved with a similar, but larger setup many years ago with a rackful of Crown amplifiers driving 1kVA transformers. They amplifiers were badly damaged a few times because when the computer program was stopped, it froze the instantaneous output level into the amplifier. When this happened, the amplifier input effectively had a fixed DC input signal applied. Unfortunately the ampiifier was directly coupled through to the test rig transformer. A transformer will appear as a short circuit to DC. The amplifier overload protection to a DC fault was not great. When it did eventually cut off the output drive, the back EMF from the connected transformer destroyed the output stage. Once we understood what was going on, we were unable to significantly change the system due to time constrains, so we ended up making sure that all the drive signals to the amplifiers went smoothly to zero over several cycles when the control program was stopped or crashed. In the light of my experience, I'd be inclined to go for some 100V line amplifiers because they are made to cope with transformer loads. Do check that the frequency response and available output power is adequate at your frequency of interest. You will need to get appropriate step up transformers to go from 100V to 240V rms. If you choose a conventional amplifier, add some flywheel diodes from the output terminal to the supply rails to protect the output transistors. In addiditon, put a suitable Varistor across the transformer primary to limit the magnitude of any back EMF under fault conditions.

HUB75E suggests that it is a 1/32 scan panel. A HUB75E panel uses what is one of the Gnd pins on HUB75 connector as the 'E' pin. No - I'm not an expert but I have played with some small ones and a Rpi for curiosity.... This appears to be software configuration/setup problems. The chips used in these panels are fairly generic. It's how they're connected on the panel that really matters. Is there a part number on the rear of the panel that leads to a datasheet with a bit of google-fu? The only way I've heard of to damage these panels is if the multiplexing stops leaving a static line of extremely brightly lit LEDs - the lit LED's are only designed to be lit on a low duty cycle as the multiplexing works.

@themadhippy - fair point! Hopefully any damage will show other colours as well to highlight it.

Is the cable double insulated? A few times I've seen North American appliances where the flexible cable has only a single layer of insulation over the cores. This type of cable must be replaced because even with minor damage the cores can become exposed and dangerous. A mains flex must be double insulated. The outer sheath colour must be different from the inner core colours so that damage is noticeably obvious before someone gets hurt.

When using a short throw projector, the screen surface must be absolutely flat - a plastered wall is unlikely to be flat enough. A proper suspended projector screen is good, but you may need to secure the bottom corners to stop it moving in draughts (a very small movement will be very obvious). As Stuart notes above, a short throw projector will need to be mounted at the right point in space in front of the screen to work correctly. If you've never used a short throw projector before, borrow and play with one before you commit to buying one for your venue. You will need to take great care in how you light the rest of the stage so that your projected image is not washed out by other lighting. For a given projector, the smaller the projected image, the brighter it will be. If using a projected image as a backdrop, you can make the technical aspects simpler if the bottom edge of the projected image is above actors head-height when they're performing upstage (assuming there's enough space above the actor to the ceiling to show a useful image....)

The commercially available boards with PoE capability I've seen all have limited 5V current capability, usually sufficient to drive the CPU and a few anciliary parts. Standard PoE ports on switches/hubs are designed to supply about 12.5W to the load, higher powerd ports are available too. There are plenty of external PoE power splitters available online which will provide 2 to 2.5A at 5V. This should be enough to drive the CPU module and around 60 RGB pixels, depending on brightness, pattern etc. This will be a useful single cable solution for small set peices. Using an external PoE power splitter also increases the choice of ethernet connected CPU modules available.

I have been wanting to do simple DMX-controlled effects with LED pixel tape and run into the problems noted above. Have a look at the 'WLED' project hosted on Github. The host microcontroller is an ESP32 or ESP8266 which has built in Wifi and costs around GBP10 from the usual online sources. This is very much a DIY route, but the parts are small, cheap and easy to put in an suitable enclosure. I've started to play with it and I'm impressed. One of the E1.31/Artnet control options offered allows preset scenes (and there's a big selection included by default) to be selected by DMX control value. A related project is 'NodeMCU' which allows similar remote control of relays and triacs. For theatre use I'm not keen on wifi being used for control, but apparently there is a way of using wired ethernet in place of Wifi with these controllers.

Following @musht 's suggestion. UV produces good flourescence effects in a small space. Do take care to get the correct type of UV lamp. BLB or 'Blacklight Blue' is what you need. Do not attempt to use anything else such as insect zapper, suntan or germicidal lamps - these are all hazardous and usually don't work well with fluorescent effects. As noted above, the most cost effective BLB light source is a Fluorescent lamp type source - the unlit bulb/tube will appear black with a deep purple glow when lit. Fluorescent lamp UV sources which are clear or white when unlit may be dangerous.

They are both Class 4 laser devices. A class 4 laser device is extremely dangerous and *must* be used correctly. If you are asking here, you most likely do not have the training, knowledge or experience to use such devices safely. Don't bother thinking about using them. They are not worth the risk of inflicting life-changing injuries on your friends at a party.

An air compressor and associated parts falls under the legalities around pressurised plant and boilers (I can't remember the relevant legislation offhand). It will need to be insured and regularly inspected by the insurer. If your workplace uses similar equipment and has the processes in place to look after it, you should be OK. From a managemnt point of view, small air compressors are too easily obtained, and are regularly unexpectedly found in odd places and not on any insurance inventory.....

I've been in a similar (non-Covid) situation. The problem is a failure of local managment. The local managment will get their backsides kicked if deliveries are late or productivity is poor. They will only be held to account when somone falls ill with Covid and contact tracing starts. Most of the big supermarket workforces have good trade union representation, so your best course of action is to get the local union branch involved. In your current employment, trade union membership is well worth the membership fees to help you in this type of situation.

The person who started this thread (no pun intended) is from Australia, hence the 'good luck'. Most imperial threads I've seen recently on things are American sizes, because they are still in everyday use. I did consider suggesting altering by re-tapping, however this can significantly reduce part strength, so without knowing more about the application details, I said nothing. The simplest and quickest solution may be to change all the parts involved to a similar metric size (or whatever is locallly available).

Going by the silence, no-one knows. I'm guessing a Whitworth thread would be common for that era. Good luck finding British Imperial nuts and bolts in today's world. With a vernier caliper, a ruler and machinist's thread tables (internet search) it is straigtforward to work out what an external (male) thread is. Use the caliper to measure the outside diameter (inches) of the thread - what you measure will be slightly undersize compared to the 'official' size. With the ruler count the number of threads per inch. From the thread tables you should be able to pick out the relevant size. Internal (female) threads are harder to measure and it is usually quicker to find a bolt that fits correctly and then take measurements from the bolt. Don't forget that imperial 'things' tend to use 1/8ths and 1/16th etc of an inch which needs a bit of calculator-work after looking at a 1/1000 inch marked scale.

Depending on your house layout, a powerline network system may be appropriate. Plug a node into the wired port on your router and use a combination wired and wireless node in your music studio room. You may also need a local ethernet switch if you need more than one or two wired connections in your musc room. I've used a similar setup where I've needed a wired ethernet system in a theatre/event space with no previously installed infrastructure.

If you do come across what you suspect to be asbestos containing materials, please remember that it is the dust that is harmful. Bending or any handling of asbestos insulated wiring will release hazardous dust. Other parts around the lamp such as washers, gaskets, padding around lenses can contain asbestos as well. Old asbestos-containing light fittings should be disposed intact and complete as asbestos containing waste. At your own personal risk, if you do choose to get involved with old lamps potentially containing asbestos, I suggest you use a large container of water (no, not the kitchen sink!), submerge everything and remove all the potentially asbestos containing parts under water. Whilst the bits are still wet, double bag the waste in heavy duty plastic bags and dispose of it legally. The bits that you wish to keep (which probably will be metal,glass,ceramics and plastics only) and all the equipment used must be scrubbed clean (including gasket residues) and thoroughly rinsed several times with clean water. It is important that no residues or surface dust is left behind when everything dries.

WD40 and white spirit fumes are flammable. I hope you did not use an electric drill for this - cordless or corded. The sparks from the motor commutator can start a fire or explosion with flammable fumes present. If do have to use a power drill for this, use a compressed air powered one with the air compressor well out the way in a safe place.