The Model 3000xi Power Supply is a fully programmable and computerized instrument that incorporates several unique features. The supply offers four operating modes: standard, time, volt-hour, and step. The operator has a choice of running electrophoresis manually, for a set period of time, or for a set number of volt-hours. These parameters can be combined using the step mode. While operating in any one of the four modes, the user simply enters the desired power conditions and begins the run. The operational parameters are displayed on the LCD. Output voltage, current, and power are displayed on the LED display.</blockquote><br />
{{Infobox| class="wikitable" style="float:right; margin-left:1em; width:22em; font-size:90%;"! colspan="2" style="text-align:center; background:#eee; font-size:115%;" | title = Bio-Rad 3000Xi| subtitle -! colspan="2" style= "text-align:center; font-style:italic;" | Computer-Controlled Electrophoresis Power Supply| -! Manufacturer = | Bio-Rad Laboratories| -! Model = | 3000Xi| -! Era = | Late 1980s – 1990s| -! Output = | 25–3000 V DC, 0–300 mA, 0–400 W| -! Control = | Microprocessor, fully programmable}|}
The '''Bio-Rad 3000Xi''' is a microprocessor-controlled high-voltage power supply intended for laboratory electrophoresis — SDS-PAGE, 2-D electrophoresis, native gel, electrophoretic blotting, isoelectric focusing, DNA/RNA separations, and isotachophoresis. It produces a regulated DC output up to '''3,000 V''', '''300 mA''', and '''400 W''', with constant-voltage, constant-current, and constant-power operating modes. Date codes on the silicon place this generation of the design at '''1987–1988'''.
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{{<div style="border-left:4px solid #f0ad4e; background:#fcf8e3; padding:0.5em 1em; margin:1em 0;">'''Note|:''' REG3 vs REG4 silkscreen position needs confirmation against the TO-220 part numbers — only the REG1/REG2 silkscreen was clearly visible in image 3.}}</div>
=== Passive Components ===