Bench power supplies are a valuable tool for every lab. They are used to generate a constant DC voltage adjustable by the user. Common output ranges lie between 0-30 V DC.

What are the key factors when reviewing a lab supply?

Good variable DC power supplies have a knob for coarse and fine adjustment. Coarse adjustment is used for roughly controlling the voltage output. Fine adjustment allows us to precisely set the output voltage of the bench supply. Another important feature is current limiting. Current limiting imposes an upper limit on the DC current. This feature helps us to test electronic circuits efficiently. The user sets a curren limit and the bench power supply guarantees that the output current does not exceed this limit.

Electrical power of good lab supplies is within 100-150 W. All bench supplies should have galvanic isolation, which means that their ground should have different potentials. Thus, a good lab supply has a floating voltage output like a battery.

Some power supplies have one output channel, some have two or more channels. The number of channels usually scales with the product price. A power supply should withstand a short circuit of the output voltage.

The most important features of a bench power supply are:

  • Number of channels
  • Output voltage range
  • Coarse and fine adjustment
  • Displays for voltage and current
  • Maximum electrical power
  • Accuracy / Stability
  • Package Content

Here is a short review of the popular Tekpower TP3005T power supply: