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EOG build: where to find the parts

Checked 1 Nov 2026 1 November 2026

In short

  • The EXG Pill is not in stock at any Dutch or EU shop; in stock at Crowd Supply (US) and the maker (India).
  • Everything else is in stock in the Netherlands (Tinytronics, Kiwi) or at DigiKey NL, except a 500 mAh protected LiPo (only 1200 mAh in stock).
  • Cheapest from EU shops: about €79 (Pill on 4-week back-order). Simplest, all in stock: about €95–100.
  • Nothing has been ordered; prices and stock change daily.
On this page

This is a guide, not a recommendation to buy. Prices and stock change daily. Prices are as the shop showed them on 2026-11-01, without shipping, and “incl. VAT” / “excl. VAT” is written only where the page said so. Nothing here is a medical device. For why these parts were chosen and how to use them safely (battery only, never while charging), read Build your own eye-movement sensor (EOG) with an ESP32 first.

UK shops (The Pi Hut, Pimoroni): since Brexit, an order to the Netherlands can bring Dutch VAT, customs handling fees and sometimes duty on top of the price. The same is true for US and Indian shops.

1. BioAmp EXG Pill (Upside Down Labs)

ShopRegionProduct pagePriceStock (2026-11-01)Notes
Upside Down Labs store (maker)Indiastore.upsidedownlabs.tech₹2,599 (1 Pill); ₹5,199 (2-pack); ₹19,999 (8-pack)28 / 20 / 2 in stockSingle kit includes 1 BioAmp Cable v3 (JST-PH to snap), 3 jumper cables, 12 gel electrodes. The site ships abroad by DHL but its banner sends international buyers to Tindie, DigiKey or Mouser. Shipping cost not checked
DigiKey NLEU (ships from US)digikey.nl search, part 5075-0047-ND€34.40 (1 pc)0 in stock, “standard lead time 4 weeks”Page does not say whether cable or electrodes are included
Tindie (maker’s store)Worldwide1 Pill, 2-packUS$34.49; US$69.00Not shown; page says shipping rates for the chosen country are not set yetKit contents only shown as an image, so not confirmed
Crowd SupplyWorldwide (US)EXG PillUS$69 Explorer Pack (2 Pills); US$249 (8)In stockExplorer: 2 Pills, 15 gel electrodes, 2 electrode cables, 6 alligator clips, headers. Shipping US$18 worldwide
Robu.inIndia(product pages blocked our checker, HTTP 403)not checkednot checkedSearch snippets show an “unassembled” version in stock

Not found: Tinytronics, Kiwi, Opencircuit, Elektor, Antratek, Berrybase, Pimoroni, The Pi Hut. Mouser lists Upside Down Labs as a brand, but its pages did not load for us (not checked). No AliExpress or Amazon.nl clone found.

2. Seeed XIAO ESP32-C3

ShopRegionProduct pagePriceStockNotes
TinytronicsNLlink€6.30 incl. VAT (€5.21 excl.)200+ in stock, Eindhoven
Kiwi ElectronicsNLlink€5.82 incl. VAT (€4.89 excl.)198 in stock
DigiKey NLEUsearch 113991054€4.66 excl. VAT23,068
BerrybaseDElink€7.90 incl. VAT100+ availableWith or without headers
The Pi HutUKlink£5.10 incl. UK VATIn stockImport costs, see top
Seeed Studio (maker)ChinalinkUS$4.90In stock

3. ADS1115 16-bit ADC breakout

ShopRegionProduct pagePriceStockNotes
Adafruit (maker)US1085US$14.95In stock
DigiKey NLEU1528-1461-ND€13.27 excl. VAT (€16.06 incl.)2,927Genuine Adafruit 1085
OpencircuitNLlink€23.25 incl. VAT100 in external warehouse, 10–12 daysListed as Adafruit 1085
BerrybaseDElink€15.90 incl. VATNot available
PimoroniUKlinknot shownPre-order
TinytronicsNLgeneric module€5.50 incl. VAT100+ in stockUnbranded clone-type module (“Merkloos”); lower quality assurance
TinytronicsNLDFRobot Gravity DFR0553€17.25 incl. VAT9 in stockBranded alternative, same chip

4. Protected 3.7 V LiPo (400–1000 mAh)

The XIAO ESP32-C3 has solder pads for the battery, not a plug. A JST-PH battery needs its plug cut off or a matching JST-PH socket soldered on. Check polarity: Tinytronics warns there is no standard polarity for LiPo JST plugs.

ShopRegionProduct pagePriceStockNotes
TinytronicsNLPKCELL 500 mAh LP503035€4.75 incl. VATNot in stock (2–4 weeks)Protection circuit, JST-PH
TinytronicsNLPKCELL 1200 mAh LP503562€6.00 incl. VAT200+ in stockSlightly above the range; protection IC S-8261, JST-PH, 65×36×5.3 mm, 24 g
Kiwi ElectronicsNLPKCELL 500 mAh€5.94 incl. VATOut of stock, no backorderProtection, JST-PH
BerrybaseDELP-503035€5.10 incl. VATNot available
The Pi HutUK500 mAh£6Sold out
AdafruitUS1578US$7.95Out of stock

Not found: an in-stock 400–1000 mAh protected cell at a Dutch shop on the day.

5. Snap electrodes and snap cables

The maker’s single EXG Pill kit already includes a BioAmp Cable v3 (JST-PH to snaps) and 12 gel electrodes (maker’s store page). DigiKey’s and Tindie’s contents are not confirmed. SparkFun-style cables end in a 3.5 mm audio jack, so they need a jack socket to wire to the Pill.

ShopRegionProduct pagePriceStockNotes
SparkFun (maker)USSEN-12969, 10 × 24 mmUS$9.95In stock, “only 2 remaining”Ag/AgCl-coated sensor, 4 mm snap
OpencircuitNLsame pads€16.50 incl. VATExternal warehouse, 5–7 days
The Pi HutUKsame pads£9.60In stock, 12 left
MindfieldDE50 pre-gelled electrodes€14.90 incl. 19% VATNot statedAg/AgCl per image caption; size and snap size not stated
Tindie (Upside Down Labs)WorldwideNeo gel electrodes, 100US$19.499 left3.2 × 2.5 cm, “Ag/AgCl” solid gel, stainless snap
Crowd SupplyWorldwideNPG Lite page, accessoriesUS$20 snap cables (10); US$20 tab hydrogel electrodes (100)In stockMade for NPG Lite; fit with the EXG Pill not checked
OpencircuitNLSparkFun 3-lead cable CAB-12970€14.75 incl. VATExternal warehouse, 5–7 days3.5 mm jack
RobotShop EUEUsame cable€10.21In stock3.5 mm jack
BerrybaseDEsame cable€10.50Not available

Not found: the BioAmp Cable v3 on its own at an EU shop (Robu.in lists it, page blocked for us).

6. 5 V boost module

ShopRegionProduct pagePriceStockNotes
Adafruit (maker)USMiniBoost 4654US$3.95In stockTPS61023, 2–5 V in, 5.2 V out
DigiKey NLEUsearch 4654€3.51 excl. VAT1,853
The Pi HutUKMiniBoost£3.80In stock
Pololu (maker)USU1V10F5US$7.95“Active and Preferred”, backorders allowed0.5–5.5 V in
OpencircuitNLU1V10F5€7.10 incl. VAT619 in external warehouse, 5–7 days
TinytronicsNLgeneric 2 A 5 V boost€3.00 incl. VAT100+Unbranded, 2.7–5 V in, 80 mV ripple, no reverse-polarity protection

Whether a boost is needed at all is still open (section 7). A switching converter also adds ripple near an amplifier, which is worth testing.

7. Optional: NPG Lite (all-in-one) and BITalino EOG (reference)

ShopRegionProduct pagePriceStockNotes
Tindie (Upside Down Labs)WorldwideNPG Lite ExplorerUS$99“Only 2 left”Includes 7 snap cables, 12 gel electrodes; battery not included
Crowd SupplyWorldwideNPG LiteUS$113 Explorer / US$179 Ninja / US$240 BeastAll pre-orderShip dates shown (e.g. Ninja “Oct 30, 2026”) look stale. Ninja lists a LiPo; Beast page contradicts itself
PLUX (maker)PT (EU)EOG for BITalino€60.00No status shown, “Add to cart”Needs a BITalino base: BITalino Board €195, Plugged €225. VAT treatment not stated

Not found / unclear

  • EXG Pill in NL/EU shops: none found. DigiKey NL lists it with 0 stock. The closest in-stock sources are Crowd Supply (US) and the maker’s Indian store.
  • EXG Pill supply voltage, conflicting: datasheet says 5 V. The docs list “3.3 V / 5 V” and describe 3.3 V use via an output divider. Tindie lists “Input Voltage 4.5–40 V”. A LiPo (3.0–4.2 V) is below the Tindie minimum, which is why a boost module is on the list. Test on the bench.
  • What DigiKey’s and Tindie’s single Pill include: not confirmed.
  • Mouser.nl: pages did not load, so all Mouser prices and stock are not checked. Farnell, Reichelt, Elektor, Antratek: not checked or not found for these items.
  • Robu.in: blocked our checker, so not checked.
  • AliExpress / Amazon.nl clones: no product pages found for any of these parts. The only clone-type items listed are the unbranded Tinytronics ADS1115 and boost modules.
  • Protected LiPo, 400–1000 mAh, in stock in NL: not found. Only 1200 mAh was in stock.
  • Ag/AgCl: confirmed for SparkFun pads, the maker’s Neo gel pads and Mindfield’s. Not confirmed for the EXG Pill kit’s own electrodes.
  • Shipping costs and import VAT for US, UK and Indian orders: not checked.

Approximate baskets (one sensor channel)

Cheapest realistic from EU shops (approximate, incl. VAT where shown, plus 3 shipping charges): DigiKey NL EXG Pill €34.40 excl. VAT (about €41.60 with 21% VAT, back-order ~4 weeks) + Tinytronics XIAO €6.30, generic ADS1115 €5.50, 1200 mAh LiPo €6.00 and boost €3.00 + Opencircuit SparkFun electrodes €16.50. About €79, plus a snap cable (~€10–15) if the DigiKey Pill turns out to come without one.

Simplest basket (fewest shops, everything in stock): Crowd Supply Explorer Pack (2 Pills, cables, 15 electrodes) US$69 + US$18 shipping, plus one Tinytronics order (XIAO, ADS1115, LiPo, boost) €20.80. About US$87 + €21, roughly €95–100, before any import VAT on the Crowd Supply parcel. You get a spare Pill for a second channel. To use only genuine Adafruit boards, swap the Tinytronics ADS1115 and boost for DigiKey NL (€13.27 + €3.51 excl. VAT), which adds a third shop.

Sources