DC Power Supplies & Rectifiers

Electrically, a rectifier and a DC power supply are the same thing: an AC to DC converter. Ours run in manual and automatic modes. In automatic constant-voltage the output voltage is held and current floats up to its limit; cross the limit and the unit drops voltage to hold current. Constant-current works the same way inverted, holding current while voltage floats within its threshold.

What separates a good unit from a cheap one is protection and filtering. A good rectifier has short-circuit protection and over- and under-voltage protection on both the DC output and the AC input, a properly sized RLC bulk filter on the output, and line filters and surge arrestors at both ends. Ripple is where the consequences are visible: plating and anodising need output ripple below about 1%, and a component anodised on a rectifier with excessive ripple comes out of the bath discoloured toward black. That is a rejected batch, not a specification argument.

We build around a step-down transformer that also compensates for a sagging line, feeding a half-controlled full-wave bridge driven by an MCU-based control circuit through an isolated, PID-controlled SCR drive.

To quote, we need the purpose, the maximum DC load, and the ripple you can accept. For process work, buyers typically want a voltage setpoint and a current setpoint on local potentiometers, plus Modbus for remote setpoint control. Laboratory requirements vary far more — some specify sub-1% ripple, some specify the bridge or transformer topology outright.

Thyristor or switch-mode is the real decision. Thyristor is the choice for reliability; switch-mode where space is the binding constraint. At very high currents, cooling and ripple are the two things that become genuinely hard.