Douglas Self

http://www.douglas-self.com/MUSEUM/TRANSPORT/nwheelcar/nwheelcar.htm - a classic read 'N Wheeled Vehicles'

My personal favorite is the articulated locomotives, especially the Klein-Lindner system: http://www.douglas-self.com/MUSEUM/LOCOLOCO/klienlindner/klienlindner.… It probably took me about a week to get a full idea of how it works, and I'm hoping to create a model to help myself really understand.

My favourite page on the site is http://www.douglas-self.com/MUSEUM/TRANSPORT/nwheelcar/nwheelcar.htm (Oddly second site this week that doesn't work when you force https)

If plethora of designs in search of perfection is an indicator of something of interest, then take a look at the many variations in valve gear design, particularly for locomotives, which needed to operate reasonably efficiently over a wide range of speeds, gradients and loads. Even more so, consider the many attempts at making non-turbine rotary steam engines, wonderfully documented here: http://douglas-self.com/MUSEUM/POWER/rotaryengines/rotaryeng.htm My personal favorite is the Tower spherical engine: http://douglas-self.com/MUSEUM/POWER/tower/tower.htm Unlike most of the designs here, this one was built and even put to a little practical use.

I was having a strange feeling I’d seen this site before, but only the style, not the content. I couldn’t put my finger on it until I remembered the page on the Paris pneumatic clock network: http://www.douglas-self.com/MUSEUM/COMMS/airclock/airclock.htm (discussed on HN: https://news.ycombinator.com/item?id=19441300) The entire museum section is well worth a read, though a bit of a rabbit-hole: http://www.douglas-self.com/MUSEUM/museum.htm

The whole site for this is great. I really like the multitude of variations they had in early steam/IC engines[0]; it reminds me a lot of the expirementing we have in the software ecosystem today [0a]http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/unusualICeng.htm [0b]http://www.douglas-self.com/MUSEUM/POWER/unusualsteameng/unusualsteame…

Very true, I remember many years ago when working at Soundcraft, there was a loud bang from next door as a small mixing desk with builtin amp was powered on for the first time[1]. Large electrolytic smoothing caps fitted the wrong way round, the smell is horrendous. [1] By Douglas Self who has an excellent page about subjectivity in HiFi http://douglas-self.com/ampins/pseudo/subjectv.htm

See also Cox's Clock: https://en.wikipedia.org/wiki/Cox's_timepiece I'm sure Wikipedia used to have a much better write up, and more info on other clocks of a similar type. It's a shame they started on deleting and merging so much of the historic and esoterica - they lost a lot of accuracy and good data in the process. Now the best write up and photo is at http://www.douglas-self.com/MUSEUM/POWER/oddclocks/oddclocks.htm

Wanting to read more about this, I came across this useful page: http://www.douglas-self.com/MUSEUM/POWER/maloneliquid/maloneliquid.htm

Off topic, but Douglas Self is also the author of several remarkably good audio electronics books. For example, http://www.douglas-self.com/ampins/books/ssad3.htm .

Oh, wow, guess like I will have to take another look at this site in my free time (at the office now). I hadn't even heard about electrically heated steam locomotives until now (http://www.douglas-self.com/MUSEUM/LOCOLOCO/swisselec/swisselc.htm).

It has it's own section in the trains part of Douglas' site: http://www.douglas-self.com/MUSEUM/LOCOLOCO/brennan/brennan.htm and http://www.douglas-self.com/MUSEUM/LOCOLOCO/scherlgyro/scherlgyro.htm

That Doble engine (or its technology anyway) was used in the Besler steam powered plane. Here is a video of its flight: https://www.youtube.com/watch?v=nw6NFmcnW-8 On Douglas Self's museum of retro-tech, of course: http://www.douglas-self.com/MUSEUM/TRANSPORT/steamplane/steamplane.htm

A page dedicated to these (city wide) pneumatic networks: http://www.douglas-self.com/MUSEUM/COMMS/pneumess/pneumess.htm

There were some small steam locomotives switched to electric firing, as a way to use existing infrastructure during wartime coal shortages. It's questionable if it would scale to the levels you'd want to allow a large main-line engine to run at peak performance. http://www.douglas-self.com/MUSEUM/LOCOLOCO/swisselec/swisselc.htm

If you're referring to the pneumatic network, one of the footnotes mentions a latency of 10 seconds, but the author does the math and says that's probably not accurate, more like 58 seconds at the 20km max distance. http://www.douglas-self.com/MUSEUM/COMMS/airclock/airclock.htm

This has been around for years. Self's webpage [1] notes that class G amps date back to 1976. They've certainly been used in commercial applications and I'm certain you could buy PCB kits at some point in history. Apparently, there were a bunch of class G amps that appeared after 5.1 setups got popular, just because of how much less heat they produce per channel. If you want an efficient, small amplifier these days, class D is also an option. They're cheap, small, and powerful. Much more efficient than class G. If you are just trying to stick a speaker and amp in a musical instrument, I would start by getting an amp that is built into an IC with something that can work with a relatively simple power supply. [1]: http://www.douglas-self.com/ampins/classg/g.htm

People have been trying to find a better engine design for a long time. Pretty much all of them have tradeoffs of some kind, especially when you consider the wide variety of environmental factors that can affect a combustion engine. http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/unusualICeng.htm We'll have to see if this one does anything different.

For more monowheels, check out Douglas Self's Museum of Transport page (a wonderful old-days-of-the-internet style collection of obscure info). Here's the section on monowheels: http://www.douglas-self.com/MUSEUM/TRANSPORT/motorwhl/motorwhl.htm

The N-wheeled cars page has also been discussed on HN before: http://www.douglas-self.com/MUSEUM/TRANSPORT/nwheelcar/nwheelcar.htm https://news.ycombinator.com/item?id=19786560

It's true the whole site is full of gems! I wonder why Elon hasn't tried to go prop with high speed locos! http://www.douglas-self.com/MUSEUM/LOCOLOCO/proprail/proprail.htm

If you enjoy "unusual" engines from that site - these seem very scary: http://www.douglas-self.com/MUSEUM/POWER/petrol/petrol.htm Imagine a steam engine - in which the working fluid come from boiling gasoline...

In addition to the concrete sound mirrors there was a lot of development work done pre radar. I'm sure I've seen the Observer Corps using them south of London in WW2 to help track incoming aircraft but can't find anything specific. I did find https://rarehistoricalphotos.com/aircraft-detection-radar-1917-1940/ and http://www.douglas-self.com/MUSEUM/COMMS/ear/ear.htm which have quite a lot of photographs of various devices. On a related note last time I visited the Jodrell Bank radio telescope they had whispering dishes you could play about with. https://www.geograph.org.uk/photo/4117915

see also: http://www.douglas-self.com/MUSEUM/COMMS/ear/ear.htm

thanks for this, I learned something I never heard of before: compressed air power grid http://www.douglas-self.com/MUSEUM/POWER/airnetwork/airnetwork.htm old times weren't so low-tech, this feels like steampunk^2

I remember when microphones were physically dangerous. It mentions carbon microphones with the main supply voltage going through them: http://www.douglas-self.com/MUSEUM/COMMS/mechamp/mechamp.htm#tann. But even into the 80s, microphones plugged into portable vacuum tube amps sometimes ended up with the plate voltage (200+ volts) on them and shocked people when they touched them. Stage performers usually brushed a mic quickly with a finger before putting their lips close to it, to make sure it wasn't electrically hot. I wonder if it resulted in people being more careful what they said near a microphone too.

additional info: http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/axial-ICeng/axia…

The source article linked from the submission mentions electrically synced clocks with the master in the Observatoire. I don't know why pneumatically synced clocks were preferred. Maybe it was cheaper to integrate the clocks themselves into the system? Patents? <http://www.douglas-self.com/MUSEUM/COMMS/airclock/airclock.htm> > At the Paris Observatoire a high-standard astronomical regulator clock was kept running on correct mean time by astronomical transit observations, being corrected daily. Pulses of electricity were sent every second to secondary clocks around the city, the wires being run through ducts in the sewers. Two loops starting and ending at the Observatoire carried thirteen clocks between them, the farthest being at a distance of seven and a half kilometres, or nearly four and a half miles from the observatory. The clocks were of a high standard, so they could keep good time even if the synchronising pulses failed. (The pulses synchronised the clocks but did not drive them, they were weight-driven in the conventional way) The secondary clocks were furnished with second-hands, and were placed so that they could be easily seen from the street, usually in prominent positions. They further distributed time by sending electric signals once an hour to synchronise various public clocks. The system came into operation in 1878.

The website seems to end with a 2015 electric unicycle but not continue on with covering that form factor. Maybe because most people don't refer to those as monowheels anymore. http://www.douglas-self.com/MUSEUM/TRANSPORT/motorwhl/motorwhl5.htm#ai… Also airwheel is kind of a random brand to showcase - Trevor Blackwell made an earlier one https://www.trevorblackwell.com/eunicycle and Solowheel got the majority of the earlier patents (and royalties to this day). That form factor has come a long way since 2015 though. Check out this MotoGP style race, they're hitting 50+mph: https://youtu.be/fbX6qaWINBk?si=l2G0JnBxxCMP8a7e I see them every day whizzing across San Francisco, especially on Van Ness passing all the cars. I know there's at least two shops in SF selling them, one in Potrero and one in Hayes Valley - https://alienrides.com/collections/electric-unicycles - https://lastmilepev.com/collections/electric-unicycle-euc Unicycle seems to be the winner. The "wrap around the body" form factor seems doomed from a physics point of view. That big of a diameter has way too much leverage, and the person sitting inside has too little. So you end up doing a flip instead of stopping. As such, their required stopping distances are very long compared to unicycles which can stop as well as a bicycle, if the rider is skilled.

Very off topic, but I have been very interested in Peltier units and Seebeck engines for the last month or so; winter is indeed here. It would be interesting to see these used in a wider scale, or if it is even possible. Here are some links that describe them in more detail: Thermoelectrical Generator Kit - ThermoGenKit - http://www.youtube.com/watch?v=8mFyiYh94YE Seebeck Effect - http://www.metacafe.com/watch/1129994/seebeck_effect/ Thermo-Electric Generators - http://www.douglas-self.com/MUSEUM/POWER/thermoelectric/thermoelectric… BMW Heat-Harnessing Technology - http://www.sacarfan.co.za/2009/10/bmw-heat-harnessing-technology/ http://www.innovationsforeveryone.com/Comment_Innovation.aspx?Id=4260 http://en.wikipedia.org/wiki/Thermoelectric_effect Using both heat and cold you can create a small amount of electricity from these units. I have seen something like this used in a camp. They would place one end of a metal rod into a fire and the other in a bucket of water. Then they could create enough electricity, using some type of thermoelectric circuit, to 'trickle charge' a cell phone or GPS.