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PSMA   Precision Power Supply Meters    Home

  • 4-Digit Voltage/Current Meters for Power Supply
  • Voltage measurement to 30.00V.. factory pre-calibrated
  • Current measurement to 3.000A factory pre-calibrated
  • 12-bit measurement resolution, 0.36" high 4-digit LEDs
  • Standard with 1/16" thick 5.1" X 1" flat red plastic LED filter or optional black bezels
  • Designed for use with red-board supply kit from eBay
  • Derives all power from the red-board
  • Multiple Mounting Options

General Description

The PSMA digital panel meter provides two 4-digit LED panel meters for a benchtop power supply. It connects to the 'red-board' power supply kit board providing the meters needed to complete an adjustable 'bench' power supply. The voltage meter on the left measures to 30.00 volts while the current meter to the right measures to 3.000 amps. Both meters are factory pre-calibrated, and allow for digital user-recalibration (no pots). The meter assembly connects to the red-board with a single 6-pin connector which is wired to the red-board using the included instructions. The PSMA can optionally fast-flash the current display's decimal point to annunciate current-limiting as an alternate to a separate panel-mount LED. This is not a kit, but some models are delivered with the current meter not installed to allow user-positioning.

Available Models
PSMA-F   Full size model. 4.96" wide. Volt meter pre-installed, current meter can be installed in one of 3 positions to right. Supplied with 5.1" X 1" X 1/16" red plastic light filter to be attached over LEDs. Can be ordered with optional black bezels. Mounts on standoffs, or bezel studs.
Meter spacing: 0.9", 1.15", 1.40", 1.65" - see below
PSMA-SShort model. 4.33" wide. Volt meter pre-installed, current meter can be installed in one of 2 positions using bezel-stud mount, or 1 position if standoff-mount. Supplied with 4.5" X 1" X 1/16" red plastic light filter to be attached over LEDs.
Meter spacing standoff-mount: 0.9" only
Meter spacing bezel-stud mount: 0.9", 1.15" - see below
PSMA-MMini model. 3.8" wide. Both meters pre-installed, 0.9" meter spacing, bezel-stud mount only. (Purchase bezels separately).
Meter spacing: 0.9" only - see below

  • Low Cost -- the PSMA provides two meters that are custom configured for a power supply for less than the cost of two separate meters with 12-bit precision. Using the flat plastic red filter (no bezels) for lowest cost, the meters have a sleek modern look, and optional bezels provide a more traditional style.

  • Compact -- The 0.36" high LED digits provide meters that fit into the small space available in a typical benchtop supply. Several mounting schemes allow the PSMA to attach to the front panel with selectable meter spacing. All mounting hardware is provided. Three models offer widths from 3.8" to 4.96".

  • Optional Bezels --Using the bezels provides a frame for each meter for a commercial styling. The bezels also provide a means of attaching the PSMA without any additional standoffs or mounting brackets.

Detailed Description

The red-board uses a well known ground-sense-current power supply design. This requires that the voltage measurement be differential to compensate for the ground-sense voltage. The PSMA actually provides 3 analog channels of measurement with the 3rd channel being the ground-sense voltage. The voltage display uses this channel as well as its own channel to generate an accurate differential voltage display scaled to measure up to 30.00 volts -- the specified maximum of the red-board.
The current meter is scaled to measure up to 3.000 amps and is factory calibrated with a 1% sense resistor. The red-board contains a 5% resistor, so there are two small pushbuttons on the PSMA that allow digital re-calibration to a tighter tolerance to match your red-board resistor for better current accuracy.
The PSMA is available in customized versions for other voltage/current ranges and can even provide communications and/or remote supply control for automated test appications.
Choosing a Configuration:

With all the mounting and sizing options it can confusing to choose. It is helpful to:
  • First choose a style either with bezels that frame each meter, or a single thin flat red plastic filter that covers the pair of meters. (Bezels add to the cost).
  • Second choose a meter separation that works. Inter-digit spacing between meters can range from 0.9" to 1.65". See below
  • Third choose a mounting method. The PSMA assembly can attach to your panel using standoffs glued/screwed to your panel, or it can attach to bezel studs. Bezel mounting provides for the shortest possible width.
  • With these decisions you can choose the PSMA-F (4.96" wide 'Full size' assembly that mounts on bezel studs or standoffs), the PSMA-S (4.33 wide 'Short' assembly that mounts on studs or standoffs), or the PSMA-M (3.8" wide 'Mini' assembly that mounts only on bezel studs to achieve its minimum width).
PSMA Meters      full manual
Available Positions for Current Meter
(Shown With Thin Plastic LED Filter)


Sample Supply Using Re-Purposed ATX Supply Chassis
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