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

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Click here for full schematic
(Red dots represent the "hairpin" (or left-hand or topmost) lead of the component)
Summary Build Notes
Power Supply Bill of Materials
(HF band option)
(details for installation of each component are provided in the step instructions, further down the page)
Check | Type | Category | Component | Count | Marking | Image |
---|---|---|---|---|---|---|
☐ | boardhdw | HDW | 4 X #4-40 hdw (nut, bolt, washer, spacer) | 1 |
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☐ | Capacitor | Ceramic | 4.7 uF 10% 16V X7R RAD | 2 | 475 |
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☐ | Connector | Jack-RA | DC Power Jack PCB Mount (rt-angle) 2.5mm | 1 |
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☐ | Connector | Plug | DC Power Plug 5.5/2.5mm Pos Ctr | 1 |
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☐ | Diode | Axial | 1N4003 | 1 | 1N4003 Rectifier Diode |
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☐ | IC | TO-92 | LM78L05 voltage regulator | 1 | LM78L05 ESD!!! |
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☐ | PCB | Main Board | Ensemble RX PCB (board) | 1 | ||
☐ | Resistor | 1/6W | 68 1/6W 5% | 1 | bl-gry-blk-gld |
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☐ | 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.
Check | Designation | Component (top/bottom) | Orientation | Marking | Image | Band | Notes |
---|---|---|---|---|---|---|---|
☐ | D3 | 1N4003 (top) | 1N4003 Rectifier Diode |
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any | ||
☐ | PCB | Ensemble RX PCB (board) (top) | any | ||||
☐ | R14 | 68 1/6W 5% (top) | S-N | bl-gry-blk-gld |
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any | |
☐ | U07 | LM78L05 voltage regulator (top) | LM78L05 ESD!!! |
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any | ||
☐ | C04 | 4.7 uF 10% 16V X7R RAD (top) | horiz | 475 |
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any | |
☐ | C05 | 4.7 uF 10% 16V X7R RAD (top) | vert | 475 |
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any | |
☐ | J03 | DC Power Jack PCB Mount (rt-angle) 2.5mm (top) |
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any | 2.5mm ID | ||
☐ | P1 | DC Power Plug 5.5/2.5mm Pos Ctr (top) |
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any |
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.
Check | Designation | Component (top/bottom) | Orientation | Marking | 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) |
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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) |
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

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Test Steps (if any)
Step | Test Point | UOM | Nominal | Author's | Builder'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.

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Test Steps (if any)
Step | Test Point | UOM | Nominal | Author's | Builder'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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