48 Volt Phantom Power Generator

This is a completely assembled and tested, low-noise, low-ripple DC-DC Boost Converter that generates 48 Volts suitable for powering condenser microphones.

Unlike dynamic microphones, professional small and large diaphragm condenser microphones need external powering, typically 48 Volts for it to operate properly. This is typically referred to as Phantom Power, or 48 Volt Phantom Power.

PHANTOM POWERING 48 Volts is applied to the HOT and COLD lines of the microphone via a 6.8Kohm resistor, and GND.

If you have a project, or a portable application (battery operated or not) where you need to supply 48 Volts power to a condenser microphone, this board will solve your problem. This board will generate your required 48Volts phantom power from as little as 6 Volts, to 24 Volts DC input source voltage.

BATTERY (OR DC ADAPTER) OPERATION I’ve personally tested this board using a standard, small 9 Volt rechargeable LiPo battery (which is actually just 8.4 Volts fully charge), powering a single condenser microphone at 48Volts for 14+ hours continuous operation.

LOW RIPPLE, CLEAN DC OUTPUT The board has very low ripple to make sure you won’t get any switching or noise interference on your microphone, that can be amplified by your mic preamplifier. Measured DC ripple is anywhere from 1.7mV rms to less than 3mV rms. The board also has a separate LC filter at the output to clean up the power output before going to your condenser microphone.

MAXIMUM POWER It’s been tested up to 5 Watts max output delivering 110mA of current. This is well more than enough, considering condenser microphones consume typically 3-5mA of current only, with some vintage microphones consuming 10mA max. So this is over-designed to deliver clean DC power to your microphone.

INPUT VOLTAGE VS. OUTPUT VOLTAGE (TYPICAL) The table below shows the typical DC output voltage for a given input DC voltage. Note, some microphones can still work even if not given the full 48 Volts at reduced output headroom. So for certain applications, you can power microphones from as little as 3.3Volts DC input using this board.

MINIMUM LOAD REQUIREMENT NOTE: For larger input DC voltage (12V and above), the board will require a minimum amount of load (i.e. current draw) so that output DC ripple falls below 3mV rms or less. You can use an appropriate value resistor hanging at the DC output of the board and GND.

RLoadMin = Vout / MinLoad ; use next lower available value

POWER EFFICIENCY The priority design goal of this 48V Phantom Power Generator Board is having the cleanest, lowest ripple, DC output voltage so that electrical switching noise won’t affect your sound recording from your microphone. Depending on several factors, like input voltage, and output current load, power efficiency can vary from 50% to 80%.

BOARD DIMENSIONS & PINOUTS

Square: 37mm x 37mm

Hole Locations measured relative to (0,0) lower left corner. All dimensions in inches. OPTIONAL: You can use Mill-Max Brass PCB Pins (3103-2-00-21-00-00-08-0) with Mill-Max Swage Sockets (0344-2-19-01-34-27-10-0) to mount this on your main board.

NC = No Connection