Elsewhere: Check out the through-hole version of this electroscope
This is an Electroscope done up using a design from Alan "vk2zay" Yates in his Making Electrets video.
Latest/updated (use this one): Updated electroscope (OSHPark shared project)
Older: Old electroscope (OSHPark shared project)
This BOM specifies the amount needed for one board.
| Quantity | Description | Digikey Part Number | Board Placement |
|---|---|---|---|
| 3 | 2N3906 | MMBT3906FSCT-ND | Right (label: 2N3906) |
| 3 | 2N3904 | MMBT3904FSCT-ND | Left (label: 2N3904) |
| 2 | 100 ohm resistor (0603 imperial) | 1276-5038-1-ND | Bottom (label: 100 ohm) |
| 2 | 100k ohm resistor (0603 imperial) | 1276-5110-1-ND | Middle (label: 100k ohm) |
| 2 | 1M ohm resistor (0603 imperial) | 311-1.00MHRCT-ND | Top (label: 1M ohm) |
| 1 | 9v female PCB mount snap | BSPCF | 9V+ terminal (verify before soldering by attaching to a 9V battery -- reworking afterwards is difficult without specialized tools/materials) |
| 1 | 9v male PCB mount snap | BSPCM | 9V- terminal (verify before soldering by attaching to a 9V battery -- reworking afterwards is difficult without specialized tools/materials) |
Pick either the 3mm LEDs or surface mount 0805s
| Quantity | Description | Digikey Part Number | Board Placement |
|---|---|---|---|
| 2 | 3mm LEDs | (Red: 160-1704-ND / Green: 160-1958-ND | Bottom (verify orientation before soldering!) |
| 2 | 0805 imperial LEDs | (Orange: 350-2040-1-ND / Yellow: 350-2041-1-ND | Bottom (verify orientation as with the 3mm LEDs) |
There is no part for this, so you'll have to make your own. A simple loop soldered together usually works well (the twisted termination used in the previous photos is just a fancy flourish).
Shielding: I experimented with a three-layered combination of kapton/polymide tape (to cover the BJTs), copper tape (edge to edge, touching the exposed ground edges), and then another layer of kapton/polymide to keep the copper looking nicely unscuffed by oils (from fingers).
Original design/schematic by Alan "vk2zay" Yates