Ensemble RX II (HF/LF) Power Supply
Band: HF

Introduction

General Info About the Stage

This stage supplies the "regular" 5 volt power rail, for powering the CMOS chips on the main part of the board.

Note: throughout these notes, they will refer to the board in terms of:

  • Topside: the side where one can read the silk-screened component designations and outlines
  • Bottomside: the reverse of topside, where the SMT components are installed
  • Bottom or "bottom edge": the edge of the board where all of the connectors are located
  • Top or "top edge": the edge of the board opposite of the bottom edge

Unlkess otherwise noted, all photos/graphics of the board layout are displayed herein with the top edge UP.

Theory of Operation

Stage Schematic

01_ps stage schematic

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Click here for full schematic

(Red dots represent the "hairpin" (or left-hand or topmost) lead of the component)

Board Layouts

Board Top

01_ps stage topside
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Board Bottom

01_ps stage underside
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Power Supply Bill of Materials
(HF band option)

(details for installation of each component are provided in the step instructions, further down the page)

CheckTypeCategory ComponentCountMarkingImage
boardhdw HDW 4 X #4-40 hdw (nut, bolt, washer, spacer) 1 4 X #4-40 hdw (nut, bolt, washer, spacer)
Capacitor Ceramic 4.7 uF 10% 16V X7R RAD 2 475 4.7 uF 10% 16V X7R RAD
Connector Jack-RA DC Power Jack PCB Mount (rt-angle) 2.5mm 1 DC Power Jack PCB Mount (rt-angle) 2.5mm
Connector Plug DC Power Plug 5.5/2.5mm Pos Ctr 1 DC Power Plug 5.5/2.5mm Pos Ctr
Diode Axial 1N4003 1 1N4003 Rectifier Diode 1N4003
IC TO-92 LM78L05 voltage regulator 1 LM78L05 ESD!!! LM78L05 voltage regulator
PCB Main Board Ensemble RX PCB (board) 1
Resistor 1/6W 68 1/6W 5% 1 bl-gry-blk-gld 68    1/6W 5%
wire Cutoff shunt wire (cut-off lead) 1

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Detailed Build Steps

Install Power Supply Components

Install the Diode with the lead on the cathode (banded) end forming a hairpin lead and the anode end snugged up against the board.

CheckDesignation Component (top/bottom) OrientationMarking Image Band Notes
D3 1N4003 (top) 1N4003 Rectifier Diode 1N4003 any
PCB Ensemble RX PCB (board) (top) any
R14 68 1/6W 5% (top) S-N bl-gry-blk-gld 68    1/6W 5% any
U07 LM78L05 voltage regulator (top) LM78L05 ESD!!! LM78L05 voltage regulator any
C04 4.7 uF 10% 16V X7R RAD (top) horiz 475 4.7 uF 10% 16V X7R RAD any
C05 4.7 uF 10% 16V X7R RAD (top) vert 475 4.7 uF 10% 16V X7R RAD any
J03 DC Power Jack PCB Mount (rt-angle) 2.5mm (top) DC Power Jack PCB Mount (rt-angle) 2.5mm any 2.5mm ID
P1 DC Power Plug 5.5/2.5mm Pos Ctr (top) DC Power Plug 5.5/2.5mm Pos Ctr any

Install /RX EN (Ground Point)

Install /RX EN (Ground Point)

Use a good strong piece of wire, as this will be used as a ground connection point for a number of tests throughout the build.

CheckDesignation Component (top/bottom) OrientationMarking Image Band Notes
/QSD EN shunt wire (cut-off lead) (top) any (use for regular GND connection point)
mtg_hdw 4 X #4-40 hdw (nut, bolt, washer, spacer) (top) 4 X #4-40 hdw (nut, bolt, washer, spacer) any Can install later. four each of 3/8 inch 4-40 Phillips head screws,4-40 nuts, 1/8 inch long #4 nylon spacer and #4 nylon washer 1 3/8" screw, 1 nut, 1 nylon washer, and 1/18" nylon spacer (4 each)

Completed Photos

View of Completed Topside

01_ps stage completed topside

View of Completed Underside

01_ps stage completed underside
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Test the Power Supply Stage

Power Supply - Current Draw

Measure the resistance (after the input diode) on the power input to ensure there is no short circuit. Measurement can be taken from the hairpin of D3 and the "/QSD EN" ground wire and should read in the Megohm range.

If the measured input resistance is within reason, measure the current draw with your mA meter inserted in series into the positive power lead.

See Tutorial on Measuring Current for an illustration of how to measure current in a circuit.

If you prefer to do so using a current limiting resistor, use something in the 1k-2k range and use ohms law to calculate the maximum current draw to expect for a direct short. Anything considerably lower than that maximum current draw would suggest there was no short

Current Drawgraphic
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Test Steps (if any)

StepTest PointUOMNominalAuthor'sBuilder's
1 D3 hairpin lead (WRT GND - "/QSD EN") ohms > 1M 7 M and rising         
2 Current Draw mA < 8 4.3         

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Power Supply - Voltage Test

With 12 V dc applied to the board (author's gel cell was at 12.89 Vdc), measure the voltage after D3 and measure the output of U7 (the 5 Vdc rail)

Measurements are with respect to (WRT) the regular ground plane (i.e., the non-USB side) of the board.

Voltage Testgraphic
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Test Steps (if any)

StepTest PointUOMNominalAuthor'sBuilder's
0 At Cathode of D3 (WRT regular ground) Vdc .6V less than input 12.3         
1 At hole for R27 hairpin lead (WRT regular ground) Vdc 5 4.92         

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