Excitation current source v2
About the Excitation current source v2 PCB
Excitation current source v2 is an open source PCB design by Moore-Lab, published on GitHub. It is a 4-layer board measuring 159.5 × 100 mm, with 35 components from 13 distinct parts.
Other key parts include the ADS1115IDGSR. By type, the board carries 14 resistors, 8 capacitors, 7 connectors, 4 diodes and 2 ICs.
From the project
Multi-channel 4-wire RTD readout for a LabJack T7 Pro.
Multi-channel 4-wire RTD readout for a LabJack T7 Pro.
Each RTD gets its own constant-current loop: a current-regulator diode (CRD, ~220 µA) drives a precision reference resistor Rref in series with the RTD. The RTD voltage VRTD is read on the T7's existing differential pairs; the current-sense voltage Vref is digitized on-board by I²C ADS1115 ADCs on the T7's digital lines. Each RTD is then computed ratiometrically as RRTD = C · (VRTD / Vref), where the per-channel constant C is found by one-time cross-calibration against a known resistor. This makes the result independent of the CRD's…
Main components on the Excitation current source v2
Excitation current source v2 bill of materials (BOM)
35 components, 13 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | ADS1115IDGSR ADS1115IDGS (0x48) Texas Instruments | MSOP-10_3x3mm_P0.5mm | U1 |
| 1 | ADS1115IDGSR ADS1115IDGS (0x49) Texas Instruments | MSOP-10_3x3mm_P0.5mm | U2 |
| 4 | 1984646 (PT 1,5/5-3,5-H) Conn_RTD_4W Phoenix Contact (PT 1,5/5-3,5-H, 3.5 mm pitch; pin 5 = cable shield to AGND) | TerminalBlock_Phoenix_PT-1,5-5-3.5-H_1x05_P3.50mm_Horizontal | J1, J2, J3, J7 |
| 1 | RJHSE-5380 Conn_T7_RJ45 Amphenol CS (Commercial Products) | RJ45_Amphenol_RJHSE5380 | J4 |
| 1 | 53048-0410 Conn_T7_I2C Molex (PicoBlade; mate: pre-made pigtail 2181120404, 425 mm - NO crimping) | Molex_PicoBlade_53048-0410_1x04_P1.25mm_Horizontal | J5 |
| 1 | 1984617 (PT 1,5/2-3,5-H) Conn_Power Phoenix Contact (PT 1,5/2-3,5-H, 3.5 mm pitch) | TerminalBlock_Phoenix_PT-1,5-2-3.5-H_1x02_P3.50mm_Horizontal | J6 |
| 4 | S-101T CRD ~100uA SEMITEC | D_SEMITEC_S-101T | D1, D2, D3, D4 |
| 2 | CL21B104KBCNNNC 0.1uF Samsung Electro-Mechanics | C_0805_2012Metric | C1, C2 |
| 2 | CL21A106KACLRNC 10uF Samsung Electro-Mechanics | C_0805_2012Metric | C3, C4 |
| 4 | GRM31C5C1H104JA01L 0.1uF Murata | C_1206_3216Metric | C5, C6, C7, C8 |
| 4 | TNPU12061K00AWEN00 1k Vishay (>=10ppm/C thin-film; see BOM_REVIEW) | R_1206_3216Metric | R1, R2, R3, R6 |
| 2 | RC0805FR-074K7L 4.7k Yageo | R_0805_2012Metric | R4, R5 |
| 8 | RG2012P-102-B-T5 1k Susumu | R_0805_2012Metric | R7, R8, R9, R10, R11, R12, R13, R14 |
Excitation current source v2 design files
The KiCad project lives in the Moore-Lab/excitation-current-source-v2 repository on GitHub; these links point at the commit this page was built from.
- Layouthardware/rtd-readout.kicad_pcb
- Schematichardware/rtd-readout.kicad_sch
Excitation current source v2: common questions
How big is the Excitation current source v2 PCB?
The Excitation current source v2 measures 159.5 × 100 mm, has 4 copper layers and is 1.6 mm thick.
How many components are on the Excitation current source v2?
35 components, from 13 distinct parts. The full bill of materials is listed on this page.
Where can I download the Excitation current source v2 design files?
From the Moore-Lab/excitation-current-source-v2 repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the Excitation current source v2 design in my own project?
The repository has no license, so all rights stay with Moore-Lab. Use it as a reference, and ask the author before reusing the design.