Readiness: Superb Lab Power Supply
Verdict: Ready with caveats · 2026-07-09 · est. parts cost $115–$135
This is a cold baseline check; no previous report exists for this lab. The design is implementable, but the primary power transistor and specific power relay are obsolete and require mandatory substitutes. Furthermore, the 24V AC-AC transformer and the high-precision Kelvin shunt are specialized components that require targeted sourcing as they are frequently out of stock or easily confused with incompatible AC-DC adapters. Firmware implementation is hindered by a dead library link in the original documentation.
Action required
| Part |
Problem |
Recommended action |
| 2SD1047 |
Obsolete; zero stock at major distributors. |
Use TIP35CG (onsemi) as a footprint-compatible substitute. |
| G5LE-1-VDDC12 |
Obsolete. |
Use G5LE-1 DC12 (Omron); vented (VD) suffix is not required. |
| WSL3637R0100FEA |
Out of stock at general hobbyist distributors. |
Source from specialized vendors (e.g., Future Electronics or TTI). |
| 24V AC Transformer |
High risk of purchasing incorrect AC-DC adapter. |
Ensure transformer is 24V AC-AC (e.g., Ensign L100-2-524). DC input is forbidden. |
| LiquidCrystal Library |
Original Bitbucket link is dead. |
Redirect students to the GitHub mirror: github.com/fmalpartida/New-LiquidCrystal. |
Parts
Integrated Circuits and Semiconductors (Digital Meter Board)
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| IC1: MAX44284FAUT+ |
Current Amp / SOT23-6 |
Ready |
2,773 |
$3.66 |
DigiKey |
| IC2: MCP3422A0-E/SN |
ADC / SOIC-8 |
Ready |
4,069 |
$3.72 |
DigiKey |
| IC3: MCP6061T-E/OT |
Op-Amp / SOT23-5 |
Ready |
574 |
$0.84 |
DigiKey |
| Q1, Q2: BC817-25LT3G |
NPN / SOT23 |
Ready |
3,187 |
$0.17 |
DigiKey |
| D3: BAT54 |
Schottky / SOT23 |
Ready |
424,390 |
$0.14 |
DigiKey |
| Z1: 824501361 |
TVS 36V / SMA |
Ready |
4,611 |
$0.29 |
DigiKey |
Integrated Circuits and Semiconductors (Analog PSU Kit)
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| U1, U2, U3: TL081CP |
Op-Amp / DIP-8 |
Ready |
10,105 |
$0.70 |
DigiKey |
| Q1: 9014 |
NPN / TO-92 |
Ready |
>100 |
$0.08 |
Addicore |
| Q2: 2SD882 |
NPN / TO-126 |
Ready |
8,181 |
$2.50 |
DigiKey |
| Q3: 9015 |
PNP / TO-92 |
Ready |
>100 |
$0.08 |
Addicore |
| Q4: 2SD1047 |
NPN Power / TO-3PL |
Obsolete |
0 |
— |
— |
| D1-D4: 1N5408 |
Rectifier / Axial |
Ready |
41,798 |
$0.35 |
DigiKey |
| D5-D10: 1N4148 |
Signal / Axial |
Ready |
1M+ |
$0.10 |
DigiKey |
| D7, D8: 1N4733A |
5.1V Zener / Axial |
Ready |
85,582 |
$0.26 |
DigiKey |
| D11: 1N4004 |
Rectifier / Axial |
Ready |
128,112 |
$0.14 |
DigiKey |
| D12: LED |
5mm T1-3/4 |
not checked |
— |
— |
— |
Passives (Digital Meter Board)
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| R4: WSL3637R0100FEA |
0.01 Ω Shunt / 3637 |
At risk |
>100 |
$1.05 |
Future Elec |
| Resistor Kit |
0603 Variety |
Ready |
>100 |
$39.95 |
Adafruit |
| Capacitor Kit |
0603 Variety |
Ready |
>100 |
$39.95 |
Adafruit |
Passives (Analog PSU Kit)
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| Power Resistor |
0.47 Ω 5W / Radial |
Ready |
605 |
$1.26 |
DigiKey |
| RV1: 3296W-104 |
100k Ω Multi-turn |
Ready |
>100 |
$2.38 |
Mouser |
| Panel Potentiometers |
10k Ω Linear |
Ready |
>100 |
$0.95 |
Adafruit |
| Axial Resistor Kit |
0.25W Variety |
Ready |
>100 |
$9.95 |
RobotShop |
| Electrolytic Kit |
50V Minimum |
Ready |
>100 |
$5.99 |
ShillehTek |
| Film/Ceramic Kit |
Various |
Ready |
>100 |
$14.95 |
Electronix Exp |
Electromechanical and Chassis Hardware
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| K1: G5LE-1-VDDC12 |
Power Relay / DIP-5 |
Obsolete |
0 |
— |
— |
| Arduino Uno R3 |
Microcontroller |
Ready |
>100 |
$4.99 |
Micro Center |
| 20x4 I2C LCD |
Character Display |
Ready |
>100 |
$4.50 |
Elecrow |
| Transformer |
24V AC / 100VA |
Ready |
>100 |
$25.67 |
PowerVolt |
| Heatsink for Q4 |
TO-247 Large |
Ready |
>100 |
$7.60 |
DigiKey |
| Enclosure |
Aluminum Box |
Ready |
>100 |
$7.99 |
eBay |
| Terminal Block |
4-way 5.08mm |
Ready |
144 |
$1.94 |
DigiKey |
| Molex Connectors |
KK 254 Series |
not checked |
— |
— |
— |
| Pin Headers |
0.1 inch |
not checked |
— |
— |
— |
| Binding Posts |
Banana Sockets |
not checked |
— |
— |
— |
| Cooling Fan |
24V DC |
Ready |
>100 |
$5.45 |
CoolerGuys |
Substitutes
| For part |
Substitute |
Differences |
Judgment |
| 2SD1047 |
TIP35CG |
TO-247 package; 25A rating exceeds original 12A. |
Recommended. |
| G5LE-1-VDDC12 |
G5LE-1 DC12 |
Suffix difference; identical footprint and coil. |
Recommended. |
Verify any substitute against its datasheet before ordering.
Other dependencies
- Firmware:
DCmeter.ino target for Arduino Uno (not checked).
- Library Dependency:
LiquidCrystal_I2C. Original link is dead; use GitHub mirror at github.com/fmalpartida/New-LiquidCrystal.
- Fabrication: 2-layer PCB (not checked).
- Calibration: Requires manual adjustment of RV1 until output is 0V at minimum setting.
- Input Constraint: 24V AC only; DC input is forbidden by design.
Watch list
- WSL3637R0100FEA: This 4-terminal Kelvin shunt is specialized and frequently has zero stock at major distributors (DigiKey/Mouser).
- 24V AC-AC Transformer: Retailers often provide AC-DC power bricks when "24V transformer" is searched. Chassis-mount AC-AC units must be manually verified.