DC Power Supplies

Technical and Reference >> DC Power Supplies

Regulated and unregulated power supplies

UNREGULATED POWER SUPPLIES
An unregulated power supply will have a varied output voltage if the current being drawn from the appliance it is connected to does not match the current rating of the power supply.

For example, a 12VDC, 500mA unregulated power supply connected to a 12VDC, 300mA portable stereo will have an increased voltage output because the current being drawn from the stereo does not match the current rating of the power supply. ie. If the current from the stereo is lower than that of the power supply, the power supply outputs a higher voltage.

Therefore, great care is needed using an unregulated power supply. Ensure that the current being drawn matches the current of the power supply - otherwise the product you are powering could be damaged.

REGULATED POWER SUPPLIES
A regulated power supply will have a constant output voltage even if the current being draw from the appliance is less than the current rating of the power supply.

For example, a 12VDC, 500mA regulated power supply connected to a 12VDC, 300mA portable stereo will have a voltage output of 12VDC even though the stereo only draws 300mA from the power supply. As long as the appliance connected to the regulated power supply does not exceed 500mA (in this case), the voltage will always remain at 12VDC.

Plug connections

BEFORE connecting a power supply to an appliance, you must first check that the polarity (positive & negative) of the output plug is correct, or damage to the appliance may occur. Your appliance should have a diagram next to the input socket showing whether the appliance requires TIP POSITIVE or TIP NEGATIVE. To do this, simply align the word "TIP" on the side of the output connector socket to the positive or negative sign on the side of the DC or Phono plug. This must be done correctly for your appliance to operate.

Tip Positive

Symbol on appliance


Plug to cable alignment


Tip Negative

Symbol on appliance


Plug to cable alignment