Generator

The Faraday disk was the first electric generator. The horseshoe-shaped magnet created a magnetic field through the disk. When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact, through the external circuit, and back into the center of the disk through the axle.

Generators are devices that create or convert one type of energy into another. For instance, an electric generator transforms mechanical energy into electric power for use in an external circuit.

Electric generator

The main consideration before building an electric generator is determining the characteristics of the device to be powered. Loads can be classified as inductive or resistive, may require alternating or direct current, and differ in terms of required voltage, current (amperage), frequency, number of phases, and sensitivity to voltage fluctuations or electrical noise.

The second consideration is the energy source that will power the generator. Thermodynamic laws state that the energy invested in spinning the generator will always be greater than the generator’s electrical output. Therefore, realistic expectations must be set regarding the size of the loads that can be powered. For example, a crank-driven generator (10 watts) is typically only sufficient to power a small FM radio or charge a cellphone—usage being limited by the physical endurance of the person cranking it. Powering larger loads such as a computer or refrigerator (100–1000 watts) would require an internal combustion engine or a sophisticated gearbox system, powered by an external source. A gearbox mechanism is designed to convert a substantial, slow-moving force into significantly faster speeds with reduced torque. (i.e. horse treadmill, gravity battery, hydropower turbine)

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Materials Needed for an Electric Generator

In a survival or civilization-rebuilding context, constructing an efficient generator from scratch is often unrealistic due to the need for machine shop tools. More viable approaches include repairing an existing generator or repurposing an electric motor to work as a generator. However, it's possible to build a rough prototype by using an iron core (Note: you can replace the typical aproach of this model with a magnet, but its difficult to get one stronger enough in the nature), some copper wires and wooden fan blades. If you are in a zone with high-speed winds, it's prefered to make the generator like a small eolic turbine; but if is not the case, you could boil water with charcoal and use the steam to powered the turbine.

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Generator Repair

The main parts of a generator include an internal combustion engine, the generator unit itself, and control circuitry. To produce power, all three components must function as an integrated system.

Internal combustion engines require fuel, oil, air, and ignition via an electrical spark. Old gasoline can corrode and clog the internal components. The air filter may be clogged with dust and vegetation—clean as needed. The spark plug might be dirty or disconnected, preventing ignition.

The generator and its control circuitry typically do not contain user-serviceable parts, especially in a survival scenario.

See: Gasoline Engine

See: Full-Wave Rectification

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Repurposing an Electric Motor as a Generator

The principle of electromagnetic induction allows an electric motor to convert electrical power into rotational movement—and this principle can also work in reverse. Some electric motors will generate electrical current at their terminals when the shaft is spun by an external force. The power output will correlate with rotational speed, and increasing the load will make the motor harder to turn.

Picture showing an electric motor attached to a bicycle wheel to power a light bulb

Picture showing an electric motor attached to a bicycle wheel to power a light bulb

The electric current produced by a repurposed motor may not be suitable for immediate use. The first priority is implementing a way to measure the generator’s power output to avoid damaging connected equipment. Second in order of priority is to regulate the generator’s rotational speed, as this directly affects the voltage and frequency of the output. Third will be converting / rectifying the current from AC to DC, and stepping down to the exact required voltage.

AC current frequency stability

AC current also has a frequency, i.e how many times a second it oscillates from positive to negative, contemporary systems in north America run on 60Hz, in Europe it is 50Hz, when rectifying power into AC from DC you need to make sure it doesn't deviate too much from the frequency as well as the voltage, generally speaking the more modern the connected equipment the more sensitive to frequency swings it will be, most generators that have a built-in rectifier will also keep frequency in check, if the generator and or rectifier is improvised avoid plugging in any load that converts AC to DC power as that can cause at best the equipment to not work and at worst overheat/destroy the power supply.

Connecting two or more generators together

AC generators should not be connected together, unless they are first synchronized and then kept in synchrony both in phase and frequency, in a survival scenario this can be checked with incandescent lightbulbs connected to both generators, one per phase and then adjusting one of the generators until all the bulbs go dark, at that moment the generators are roughly in sync, they can then be connected together, however if a synchroscope can be salvaged that is a much better and precise way to achieve this synchrony, they are usually found at powerplants and other facilities that generate power be it for grid purposes or if a facility has multiple generators and is older it should also have some sort of synchroscope that can be salvaged and just reused.

Dependencies

• Electricity
• Generator
• Energy
• Fuel

See also

• Combined cycle plant
• Fuel
• Heat

References

This article uses material from the Wikipedia article Generator, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).

This article uses material from the Wikipedia article Electric_generator, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).

External links

• Can You Magnetize Iron Just By Tapping It? - The Action Lab, 30 January 2022, YouTube
• Dr. STONE Generator - Sammzor, 7 January 2021, YouTube