Incomplete archive. This is all the information that could still be found for this meter. Other notes and docs were lost over time. The KiCad files are older and may contain errors, incomplete footprints, or value typos. Use them as a reference, not a guaranteed build package.
What it is
Each LM3914 drives a 10-segment LED bar. Cascading twenty of them gives a long, fine-resolution linear LED scale for voltage. A Ref102-class precision reference sets the measurement baseline; trimmer and resistor networks adjust span. Supporting analog parts on the schematic include TL064 and LM358 op-amps and an LM317 regulator section.
The project folder name 3914-20 is shorthand for LM3914 × 20.
What you can download
Anyone may download these files. No account required.
- Full project ZIP — KiCad schematic/PCB, libraries, netlist, enclosure DWGs, and a short README
- 3914.sch — legacy KiCad schematic
- 3914.kicad_pcb — PCB layout
- 3914.kicad_pro — KiCad project
- 3914.net / 3914.xml — netlist exports
- 3914-20-box.dwg, jim-box.dwg — enclosure / plastics drawings
- rescue-backup/ — older 2018 rescue snapshot (browseable)
Major parts (from the schematic)
| Qty | Part | Role |
|---|---|---|
| 20 | LM3914 | Dot/bar LED driver (linear) |
| 20 | BarLED (10-seg) | Display segments |
| 1 | Ref102cp | Precision voltage reference |
| 8 | TL064 | Quad op-amp support |
| 4 | LM358 | Dual op-amp support |
| 1 | LM317 | Regulator |
| 1 | Trimmer pot (RV1) | Calibration |
Many discrete resistors and capacitors are also on the sheet (including several labeled only as generic R_Small / CP in the old library). Expect to verify values against a real board if you rebuild it.
KiCad notes
- Schematic is legacy
.schformat (KiCad 4 / early 5 era). Open with a modern KiCad via the legacy importer, or keep an older install handy. - Symbol libraries ship in-tree (
3914-cache.lib,3914-rescue.*). Paths may need fixing after you unzip. - Known quirks in the archive include odd value strings (for example a resistor marked
9.88kk) and editor backup clutter (left out of the ZIP). - Last clear project timestamp in the old
.profile: 12 December 2018.
License / use
Personal bench project by James Burney (K9DTV), shared so others can study or attempt a rebuild. No warranty. If you publish a derivative, a credit to K9DTV is appreciated.