Modification, restoration and demise of an analog computer for $ 3 million

In the arsenal of professional craftsmen, in addition to the usual set of tools, there is always a construction hair dryer, which differs from the household one in the speed of air exchange and high operating temperatures. There are several types of this equipment, and each model differs in technical parameters and equipment.

What is and what a blow dryer looks like

Many employees are interested in the question of what a building hairdryer is needed for and how to use it correctly. So, the tool supplies air to the material. Outwardly, it looks like a household hair dryer. However, the air temperature at which it operates is much higher than that of the latter.

  • From the housing under which the engine is located.
  • There is a fan on the internal spindle of the device.
  • The casing has an outlet nozzle through which the air jet is supplied.

Some models have a long handle on which the start button and mode switch are located, which further adds to the tool the resemblance to a regular household hairdryer.

Due to this shape, another name was assigned to the tool - a heat gun. Most models have rubber pads on the handle that prevent slipping.

Important! Massive models of thermal guns are expensive. However, the general opinion of workers is that it is inconvenient to work with a heavy tool, as the hands quickly get tired.

Types of building hair dryers

A technical hair dryer is a specialized tool used in finishing, renovation, construction, production and other types of work.

There are several types of hot air guns by type:

The Stihl chainsaw is a device that has been trusted by a huge number of men for thirty years. Consistent quality and excellent behavior in work - all this holds from the first batches of chainsaws to this day. Even the manufacturers did not change the design of the device. The only drawback of the Stihl chainsaw can be called a huge number of fakes, which are collected somewhere in basements by hand or on primitive machines. The quality of such products is inferior to the original samples, but, in principle, it is possible to work with them.

But the point is different - some sellers try to sell a fake under the guise of the original. The difference in price and quality is enormous.

If earlier a fake chainsaw had a primitive appearance, even from a distance not like the original, now the copies are as close as possible to genuine devices.

For this article, a comparison was made between the original and fake Stihl MS 170/180 chainsaw. To be sure that you are purchasing an original chainsaw, pay attention to the following parts of the device.


Boxes of devices are identical in appearance. But there is a difference in size - the original box is a couple of centimeters longer than the fake one.

In addition, the original box must have a sticker indicating:

  • chainsaw model,
  • country of origin (China),
  • barcode;
  • serial number devices.

The number has nine positions and is assigned separately to each saw.

This number is required - without it, repairs in the service center are impossible.

But how do you choose a good model? First of all, you should decide on the class of the instrument - household, professional or semi-professional.

This affects not only the performance of the device, but also its capabilities in general.

This rating will help you to find the right chainsaw in terms of price / quality ratio. It describes the best models of chainsaws from different manufacturers according to the 2021 version.

When choosing the models, not only the advice of professional builders, specialists, feedback from the owners, but also the official data of practical tests by Rostest were taken into account.

Rating of TOP-best chainsaws of the year

Chainsaw selection parameters

Understanding the relationship of each chain tool characteristic will help you select the right tool for your application. Here are the main parameters and their purpose.

Bus length

This characteristic has a range of 30 to 60 cm, which affects the ability of the tool to cut a certain diameter of the trunk in one go:

1. Models with a parameter of 35-38 cm are suitable for harvesting firewood, cutting knots and small jobs in the yard. It will work to cut a tree with this device, but you may have to make two saws to cut through the entire trunk.

How in the 1940s was it possible to record the output of your three millionth analog computer at high speed if the results of its operation are only visible on analog meters? This problem was faced by a team at the Georgia Institute of Technology responsible for a computer that was used to study the properties of AC power grids. They came up with a clever solution - to hack the control panel and connect a special drawing table to it.

What is this?

What kind of beast is this - an analog computer? Similar machines were developed during and after World War II. Strictly speaking, it would be more correct to class them as scale models than to call them real computers. Although they were quite flexible, they were mainly designed to simulate power grids. The theory of their operation is quite extensive, but for measurements, a scale model of real multiphase power transmission networks operating on one phase and a frequency of 400 Hz was simply built.

Engineers "programmed" the machine by connecting the necessary circuit elements (capacitors, inductors, transmission lines, generators, etc.) on large patch panels. After that, a 10 kW generator located in the basement was started up, and the simulation began to work.

Part-time work

In the early 1980s, my first challenge in college was to restore one of these machines to working order. In 1947, it was bought by Georgia Power and donated to the Georgia Institute of Technology. There she worked practically without interruption for several decades. Then for some time it was used as a teaching aid, and transported a couple of times. When I entered the game, it had not been used for a long time and was in a deplorable state.

Surprisingly, it turned out to be quite easy to repair. It was necessary to replace the patch panels, since all the insulation on them was dry and cracked. The dirt accumulated there for decades had to be removed from the switches and contacts of all elements of the electrical circuit. For several semesters, this quiet basement was my refuge. I used it when I needed to sit in silence, study, or read. Sometimes I amused myself by running the machine to calculate some of the problems from the textbook on calculating AC networks.


After the generator was started and stabilized at the desired frequency, the simulated network could be monitored by connecting the measurement loops of the operator console to any element of the circuit. This was done by pressing a button with the appropriate designation on the keyboard, which looked like an old mechanical adder (perhaps it was). Almost immediately, data on the current, voltage and power consumption of the element appeared on the devices. The quantities were composite, so both the quantity and the phase were shown on the meters.

Operators received the result of simulations by sequentially going through all the necessary elements of the circuit. After each measurement, they paused to write down the numbers in a notebook, and then moved on to the next item.

Interestingly, this whole system was one passive circuit with no active components. Of course, there were relays in it for connecting measuring instruments, and the generator provided energy. But besides that, all this reading of data from the console was no different from how if a technician with a multimeter walked around the entire circuit and manually took readings. One exception was that one of the measuring instruments was powered by an electronic tube amplifier. However, it was only used for one type of measurement - in my opinion, it was VARS. Even with the amplifier turned off, the machine was fully operational and useful.

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