Hardware laboratory technicians will often have to rely on a bench supply, which provides direct current power to circuits on a temporary basis. The traditional manner of doing so is to use a series of switched circuits that are all connected to a series of variable inductors, which are often called movable chokes or reactors. Changing the output power of the system required turning several knobs and hoping that the operator was able to zero in on the exact position necessary for a particular circuit.
Analog electronics are prone to drifting, however, especially when they start to get beyond a certain temperature point. Take a look at any resistor’s bands and it quickly becomes obvious that the part in question is only accurate to within a certain specific tolerance. A component that claims to offer 250? of resistance is usually going to be able to do so only when the temperature is within a pair of percentages. Once a circuit gets used for some period of time, heat begins to build up and this will change said resistance. Poorly made resistors could end up offering less than 190? or more than 250? depending on circumstances.
Bench supplies based around a programmable power source allow direct digital control of the current flowing out of them. Technicians are able to simply dial in a different type of current when desired, and the programmable power source will respond by providing the correct kind of electron flow measured to within a tolerance that’s orders of magnitude smaller than those provided by conventional analog devices.
