Power Supply Introduction
General
This stage supplies the "regular" 5 volt power rail, for powering the CMOS chips on the main part of the board and providine the 2.5V rails via voltage dividers.
Following the diode at the power input point, there is a 12V dc takeoff for powering the pre-amp in the RF/Control Stage.
Top, Bottom Orientation
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
Unless otherwise noted, all photos/graphics of the board layout are displayed herein with the top edge UP.
(go directly to build notes)Power Supply Schematic
(Resistor testpoints (hairpin, top, or left-hand lead), as physically installed on the board, are marked in the schematic with red dots)
(above schematic has clickable areas that can be used for navigation)
(go directly to build notes)Power Supply Bill of Materials
Stage Bill of Materials
(resistor images and color codes courtesy of WIlfried, DL5SWB's R-Color Code program)
| Check | Designation | Component | Marking | Category | Orientation | Notes | Circuit |
|---|---|---|---|---|---|---|---|
| ❏ | mtg_hdw | 4 X #4-40 hdw (nut, bolt, washer, spacer) |
 | HDW | (optional) install the mounting hardware | Power Supply | |
| ❏ | PCB | Ensemble RX PCB (board) | Main Board | Power Supply | |||
| ❏ | D03 | 1N4003 | 1N4003
 | Axial | S-N | Mount as hairpin | Power Supply |
| ❏ | R11 | 68 1/6W 5% | bl-gry-blk-gld
 | 1/6W | S-N | Power Supply | |
| ❏ | U06 | LM78L05 voltage regulator | LM78L05
 | TO-92 | flat side to left | Power Supply | |
| ❏ | C05 | 4.7 uF 10% 16V X7R RAD | 475
 | Ceramic | horiz | Power Supply | |
| ❏ | C06 | 4.7 uF 10% 16V X7R RAD | 475
| Ceramic | vert | Power Supply | |
| ❏ | Cbl2 | Power-Leads for 12V | User-Supplied | Power Supply | |||
| ❏ | J03 | DC Power Jack PCB Mount (rt-angle) |
 | Jack-RA | Power Supply | ||
| ❏ | P1 | DC Power Plug 5.5/2.1mm Pos Ctr |
 | Plug | Solder appropriate 12V power leads onto this plug | Power Supply | |
| ❏ | /QSD EN | shunt wire (cut-off lead) | Cutoff | Install as ground test point | Power Supply |
Power Supply Summary Build Notes
- Install Topside Components
- Test the Stage
Power Supply Detailed Build Notes
Top of the Board
Install Topside Components
Install the resistor and diode first, then the voltage regulator, then the caps, and, finally the Jack and the ground point
Install the diode in a hairpin fashion, such that the catgode (the band) end is the hairpin.
The kit allows you to build it so as to support PTT switching in and out of the Quadrature Sampling Detector by connecting/disconnecting the "/QSD EN" (pins 1 and 2 of U8) to ground. Herein, we will use the simpler scenario of full-time QSD enabling by mounting the shunt wire on the QSD-EN connections on the board (also serves as a convenient ground test point)
| Check | Designation | Component | Marking | Category | Orientation | Notes |
|---|---|---|---|---|---|---|
| ❏ | mtg_hdw | 4 X #4-40 hdw (nut, bolt, washer, spacer) |
| HDW | (optional) install the mounting hardware | |
| ❏ | PCB | Ensemble RX PCB (board) | Main Board | |||
| ❏ | D03 | 1N4003 | 1N4003
| Axial | S-N | Mount as hairpin |
| ❏ | R11 | 68 1/6W 5% | bl-gry-blk-gld
| 1/6W | S-N | |
| ❏ | U06 | LM78L05 voltage regulator | LM78L05
| TO-92 | flat side to left | Take ESD precautions |
| ❏ | C05 | 4.7 uF 10% 16V X7R RAD | 475
| Ceramic | horiz | |
| ❏ | C06 | 4.7 uF 10% 16V X7R RAD | 475
| Ceramic | vert | |
| ❏ | Cbl2 | Power-Leads for 12V | User-Supplied | |||
| ❏ | J03 | DC Power Jack PCB Mount (rt-angle) |
| Jack-RA | ||
| ❏ | P1 | DC Power Plug 5.5/2.1mm Pos Ctr |
| Plug | Solder appropriate 12V power leads onto this plug | |
| ❏ | /QSD EN | shunt wire (cut-off lead) | Cutoff | Install as ground test point |
Power Supply Completed Stage
Top of the Board
Power Supply Testing
PWR Resistance/Current Draw
Test Setup
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.
Test Measurements
| Testpoint | Units | Nominal Value | Author's | Yours |
|---|---|---|---|---|
| D3 hairpin lead (WRT "/EN QSD" ground point) | Ω | > 1M | 7M and rising | _______ |
| Current Draw | mA | < 8 | 4.3 | _______ |
Voltage Tests
Test Setup
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.
Test Measurements
| Testpoint | Units | Nominal Value | Author's | Yours |
|---|---|---|---|---|
| At Cathode of D3 (WRT regular ground) | V dc | 0.6 less than input voltage | 12.3 | _______ |
| At hole for R18 hairpin lead (WRT regular ground) | V dc | 5 | 4.94 | _______ |