Editing DC-to-DC converter (section)

==History==
{{See also|Antique radio#Car radios}}
Before the development of power semiconductors, one way to convert the voltage of a DC supply to a higher voltage, for low-power applications, was to convert it to AC by using a [[vibrator (electronic)|vibrator]], then by a step-up [[transformer]], and finally a [[rectifier]].<ref name=vib>{{cite web |url=http://www.radioremembered.org/vpwrsup.htm |title=Vibrator Power Supplies |newspaper=Radioremembered.org |access-date= 18 January 2016}}</ref><ref name="Brorein2012">{{Cite web
| title = Watt's Up?: What Is Old is New Again: Soft-Switching and Synchronous Rectification in Vintage Automobile Radios
| author = Ed Brorein 
| work = Keysight Technologies: Watt's Up? 
| date = 2012-05-16
| access-date = 2016-01-19
| url = http://powersupply.blogs.keysight.com/2012/05/what-is-old-is-new-again-soft-switching.html
}}</ref> Where higher power was needed, a [[motor–generator]] unit was often used, in which an electric motor drove a generator that produced the desired voltage. (The motor and generator could be separate devices, or they could be combined into a single "dynamotor" unit with no external power shaft.) These relatively inefficient and expensive designs were used only when there was no alternative, as to power a car radio (which then used thermionic valves (tubes) that require much higher voltages than available from a 6 or 12&nbsp;V car battery).<ref name=vib/>

The introduction of power semiconductors and integrated circuits made it economically viable by use of techniques described below. For example, first is converting the DC power supply to high-frequency AC as an input of a transformer - it is small, light, and cheap due to the high frequency — that changes the voltage which gets rectified back to DC.<ref>There is at least one example of a very large (three refrigerator-size cabinets) and complex pre-transistor switching regulator using thyratron gas-filled tubes, although they appear to be used as regulators rather than for DC-to-DC conversion as such. This was the 1958 power supply for the IBM&nbsp;704 computer, using 90&nbsp;kW of power.[http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/ibm/704/223-6818_704_CE_Manual/736_741_746_PwrSupply_CE_Oct58.pdf]</ref> Although by 1976 transistor car radio receivers did not require high voltages, some [[amateur radio]] operators continued to use vibrator supplies and dynamotors for mobile [[transceiver]]s requiring high voltages although transistorized power supplies were available.<ref name=arrl1976>[https://archive.org/details/RadioAmateurHandbook1976 Radio Amateur's Handbook 1976], pub. [[ARRL]], p331-332</ref>

While it was possible to derive a ''lower'' voltage from a higher with a [[linear regulator]] or even a resistor, these methods dissipated the excess as heat; energy-efficient conversion became possible only with solid-state switch-mode circuits.