Member postings for Robert Atkinson 2

The compound you used before on tuning slugs was probably Rocol Kilopoise 868S (or 868GW). It seems to have been discontinued.**LINK**

Robert G8RPI.

Demand may be falling at the moment but that is set to change with electric vehicles and plug-in hybrids. Wind and solar aare no good for baseload and practical storgae is nowhere in sight. Offshore wind is not cheap.

Robert G8RPI.

One aspect of smart meters that has not been mentioned is that they have contactors fitted internally. This means that the supplier can disconnect the supply remotely. While there are currently restrictions on when they can disconnect, these may change. Another use for the contactors is rolling black-outs during times of energy shortage. individual disconnecton makes this easier and consumers with special needs can be excluded from the black out.

The high cost of buliding nuclear power plants is mostly due to regulation and administration. Interestingly the cost of building Hinkley C is about the same as building an off-shore wind farm of similar capacity. The rub is that the windfarm has only half the working lifetime. Modern reactor designs take more account of de-commissioning reducing costs. No one has de-commissioned a large off-shore wind farm yet.

Robert G8RPI.

There is such a thing as free electricity (in the UK). As long as you own an electric or plug-in hybrid car and your employer lets you charge it at work. HMRC changed the rues last year and it's no longer a taxable benefit.

Robert G8RPI.

One advantage of Cerrobend is that it expands slightly on freezing making a tighter packing. Lead shrinks. Water expands too, maybe too much.

Another thought came to me. Electroless nickel immersion gold plating (ENIG) has become popular on printed circuit boards for electronic assemblies. This two layer system will work on brass. If you have a PCB manufacturer near you it might be worth giving them a call.

Robert G8RPI.

Well first you need an EPP licence for the potassium cyanide (despite this people still seem to be selling kits on ebay). Have you checked with professional plating services? it may not be as expensive as you think especially if you are not in a rush.
You don't have to polish the surface but it will "enhance" the finish. So polished, machine turned or consistent sand blasting is OK but if there are scratches or odd marks they will show up.

Robert G8RPI.

Unfortunatly most modern British airships have not been a great sucess commercially, but the Airlander could be. It's a lifting body design that has many advantages.

The accident it suffered was not a forced landing or even a problem with the airship itself. A winch in the mooring tower failled after the mooring rope was attached. The aircrew thought it had detached and tried to fly away. The airship pivioted around the rope and nose dived into th ground. They now have a release for the mooring rope at the airship end.

Can you explain this "simple op-amp crcuit" please? Perhaps you mean a boost mode switching regulator. A boost regulator will give you a constant output at higher voltage but there are limits to what it can do.

Cheap chinese version

https://www.ebay.co.uk/itm/MT3608-2A-DC-DC-Voltage-Step-Up-Regulator-Boost-Converter-Like-LM2577-XL6009/132860039749?

Robert G8RPI.

NO it's not. The police have specifically stated this was not the case and ther were several credible witnesses. Police only flew their drones after the airport was closed. The Air Navigation Order applies to them too.

1/ Why would a criminal register a drone? Limiting supply or sales would be difficult with a global market and even DIY kits **LINK**

2/ You don't need an operator. Drones can be pre-programmed and could be pre-placed on a roof days previously. GPS is not the only navigation option and you can't go jamming GPS at an airport anyway.

3/ If active "man in loop control" was needed then there are various methods that could be used for long distance control.

This is potentially a big problem and there are other variations that could make a drone more of a hazard but I'm not going to give potential wrongdoers any hints.

Robert.

The boiler test code 2018 volume 2 section 13.1.5 says

"It is considered good practice that every time steam is raised in a
boiler that if possible the safety valve is tested by lifting the spigot
to allow steam to escape. This action reduces
sticking of balls etc."

so sounds like it's not mandatory but I think you would need a good reason not to use a testable valve. Maybe boiler inspector can comment.

Hi,

the graticule goes under the eypiece see page 31 of

http://www.science-info.net/docs/b-l/BL_Stereozoom.pdf (original sales info too)

More info:

https://www.pyseroptics.com/graticules/technical-guidance-notes/how-to-size-and-fit-an-eyepiece-reticle/

calibration info

https://www.microscopeworld.com/t-microscope_reticle_measuring.aspx

Microscope service manual including cleaning cn be downloade here

https://www.manualslib.com/download/926854/Leica-Stereozoom-7.html

Teardown pictures:

https://www.eevblog.com/forum/testgear/cambridge-instruments-(bausch-lomb)-stereo-zoom-7-teardown/

Lots of graticlues cheap on ebay, most from China.

HTH

They are a nice 'scope I have one and used them for work in the past.

Robert G8RPI

Edited By Robert Atkinson 2 on 05/01/2019 13:40:04

Edited By Robert Atkinson 2 on 05/01/2019 14:43:36

In reality they don't need additional laws, it's virtually impossible to operate a UAV from a public place without breaching the exisiting law (Air Navigation Order). even if you waited until the area as clear before taking off you can't stop somene wandering into your landing area.

Edited By Robert Atkinson 2 on 04/01/2019 17:51:06

Edited By Robert Atkinson 2 on 04/01/2019 17:51:26

There are lots of options available to a determined wrongdoer. You don't have to use off the shelf devices with known technology. I bought a high speed jet propelled UAV from Holland several years ago

**LINK**

This was pre-gps and could fly a pre-programmed route using internal sensors only. £1200 including the ground support and flight programming equipment.

I'm not going to go into other options on a public forum and suggest others don't either.

Robert G8RPI.

Not really, you don't know when to stop the motor on a vice, unless there is a sensor which has not been mentioned. In simple terms a stepper motor has good static holding force i.e it resists counter torque. but they are very bad at producing a constant torque output. I guess one option would be to put a spring between the motor and load but you still need a sensor to stop the motor drive. A microswitch activated by the spring movement would work. A DC motor and current limit circuit seems much easier.

Robert G8RPI.

That is a different situation your system did not stall, it was slowed to a halt. The drive signal was stopped and the motor is still in sync. In the stall situation the rotor is out of sync with the drive signal and magnetic field. Typically the rotor is stopped (or in Georgineer's case moving in the opposite direction) while the magnetic field continues to rotate at speed. To re-sync the field rotational speed must be reduced until the rotor (and load) can re-align and lock together. If you increase the drive speed on a stepper it will accelerate smoothly to a point and then suddenly stall. There are other factors such as the coil inductance and supply voltage (these lower the current available at speed) but primarilly it's loss of magnetic lock that is the issue.

Robert .

Probably the bigest hobby contribution to WWII was amateur radio. They contributed listening stations from home as well as using their "hobby" for war emplloyment either as radio operators, training, development or manufacturing.

Georgineer is correct. When a stepper being driven at speed is stalled it looses virtually all it's torque as the time for the poles to magnetically/mechanically realign is much longer than the time the pole is energised. if ther is an opposing force it has no chance. Before the stall it depends to a large extent on inertia to stay in sync. You have to ramp the speed up and down to get full performance and any resonaces in the system can cause issues. Some stepper systems have intertial dampers (elastomeric mounted balance weights) on their shafts to help with these issues.

Robert G8RPI.

Edited By Robert Atkinson 2 on 02/01/2019 20:10:33

If the vice is powerful enough to cause injury then it needs safety precautions. Just because it was good enough in the past does not mean it's good enough now. Old lathes had no chuck guards or zerovolt releases, new ones do, even the new (and most refurbished) Myfords.
I'm not the HSE or CE police, but as a professional I feel it is important to make sure that anyone asking for advice on this sort of thing are aware of the safety implications. When doing it for someone else it rises to a whole new level. There are too many ambulance chasing lawyers and insurance companies trying to get out of claims or recover costs elsewhere to take chances. The 4X4 community have learnt this the hard way. Helping pull someone out of a snow bank or ditch is all well and good, but if they don't sign a disclaimer beforehand they, or more likely their insurers can come after you for damage actually or allegedly caused during the recovery. Just because Frankenhealy did it does not make it safe, legal or a good idea. Relying on slipping v belts to limit torque is definitely not a good idea.

Robert G8RPI.