ITR9608 (Everlight) — what it is + current pricing
Type: 5 mm slot, IR LED + phototransistor output (no logic inside; no built-in Schmitt trigger). That’s straight from the datasheet.
Typical unit pricing (USD, today):
Digi-Key – bulk table shows  .5236 @270 pcs (not normally stocked; shows pricing tiers .
Mouser – page indicates regional availability issues; list pricing commonly around  .70– .80/ea when in stock.
LCSC –  .1380 starting price for ITR9608-F (Everlight), widely in stock; also XL-ITR9608 (Xinglight) from  .0763.
Other retail/marketplaces: small packs on eBay/Amazon typically  .20– .60 per piece equivalent.


Bottom line: If you want immediate, inexpensive supply for prototyping, LCSC has the best per-unit price right now. For North-America-centric BOMs, Digi-Key/Mouser are fine when stocked but cost more.

What a Schmitt trigger does (and why you might add one)

The bare ITR9608’s output is an analog phototransistor. As a slotted vane moves, the output voltage ramps and can chatter with vibration/EMI.
A Schmitt trigger (either built-in to some interrupters or added externally) converts that slope into a clean digital edge with hysteresis:

Two thresholds (V_T+ and V_T–): input must rise past the upper threshold to switch high and fall past the lower to switch low → noise immunity and no edge chatter.

Fast edges: better timing repeatability for your CCP/Timer scheduler.
Direct MCU/FPGA-friendly logic levels.

Some slotted sensors ship with internal amplifier + Schmitt (“Photo-IC output”). Examples you can drop in if you want an integrated digital output:

Omron EE-SX3081 / EE-SX4081 (5 mm slot, Photo-IC output, CMOS/TTL compatible).
OMRON Device ＆ Module Solutions Website

Many EE-SX “3xx/4xx” families specifically call out integral Schmitt trigger/amplifier in the literature.

Your ITR9608 does not include that circuitry—it’s just LED + phototransistor (see datasheet). If you stick with ITR9608, add one of these externally:

Two easy conditioning options

Single-gate Schmitt buffer (cheap, fast, tiny)

TI/Nexperia 74LVC1G14 (1-channel, 1.65–5.5 V) or 74HC14/74HCT14 (6-channel).

Wire the phototransistor open-collector to MCU rail with a pull-up (e.g., 4.7–10 kΩ) → Schmitt input.

Optional RC (e.g., 1–4.7 kΩ with 1–10 nF) before the gate for extra de-glitch if your vane edges are slow.

Comparator with hysteresis (tunable thresholds)

E.g., MCP6561 or LMV331 with a feedback resistor to set ≈0.2–0.5 V hysteresis.

Useful if you run long cables or need specific thresholds/noise margins.

When to insist on a Schmitt stage

High-RPM pulsing with narrow slots (fast dV/dt and any wobble → chatter).

Long harnesses near ignition coils (EMI).

Dual-stack arrangements where you need crisp phase separation.

Quick pick list (so you can buy today)

Exact part: Everlight ITR9608-F — .52 @270 pcs (DK pricing), ~ .14 @ LCSC (spot pricing).

With built-in logic: Omron EE-SX3081/4081 (Photo-IC, 5 mm slot).
OMRON Device ＆ Module Solutions Website

External Schmitt buffer: TI SN74LVC1G14 (single) or 74HC14 (hex). (Standard logic families; choose to match your 5 V or 3.3 V rail.)
Fast wiring note (for your PIC build)

ITR9608 phototransistor collector → MCU Vdd with 10 kΩ pull-up, emitter → GND.

Node → 74HC14 (or MCU pin if it has Schmitt inputs); if the PIC pin isn’t Schmitt-type, insert the 74HC14/74LVC1G14.

Add 100 nF decoupling at the sensor and a series 100–220 Ω in the LED drive line; drive LED around 10–20 mA per datasheet.

Slotted opto-interrupter (plastic package):
• Everlight ITR9608-F (5 mm slot, phototransistor output). This is a very common choice in modern replications; it’s plastic-bodied and looks like what you see in most builds.
 
• Vishay TCST2103 (3.1 mm slot) – another robust, through-hole “plastic type” slotted sensor used in encoders/switching.
Vishay

Plastic slotted codewheel (the “encoder disc”):
If you don’t 3D-print the disc, a ready-made plastic codewheel on a hub works well: US Digital HUBDISK-1 / HUBDISK-2 (pick diameter & bore to match your shaft; select a low CPR like 4–64 for a distributor). These are plastic disks on an aluminum hub and are designed exactly for transmissive slot sensors.
cdn.usdigital.com
Why I’m confident this maps to what they used
The publicly available “Laser Distributor” pages explain the same architecture you’re building: IR LED + phototransistor slot switches + rotating slotted plastic disc on the distributor shaft. That matches the geometry and wiring seen in Miller/Crowder photos/videos, even though they don’t publish a brand/PN.
The ITR9608 and TCST2103 are the two most widespread, plastic, through-hole slot sensors that fit those photos and mechanical clearances; both are still in production and easy to source.
Frontiers

For the disc, builders typically either 3D-print ABS/PLA (like your STL “ROTARY OPTICAL SLOT DISC”) or use an off-the-shelf US Digital HUBDISK plastic codewheel.
US Digital

Recommended, replicable BOM (works with your PIC firmware & wiring)

Slotted opto (pick one):
• Everlight ITR9608-F (5 mm slot) — easy alignment; tolerant of wobble.
Frontiers

• Vishay TCST2103 (3.1 mm slot) — slightly tighter mechanicals, very common.

Codewheel: US Digital HUBDISK-1-64-250-NE (1″ OD, 64 CPR, ¼″ bore, NE = no-index) or HUBDISK-2-64-375-NE (2″ OD, ⅜″ bore) depending on your shaft. (If you prefer fewer events, order 4–16 CPR and cut your slot count accordingly.)
cdn.usdigital.com
 
Biasing: 5 V logic, LED side ~220–330 Ω series; phototransistor side 4.7–10 kΩ pull-up to 5 V (active-LOW when blocked), which matches your firmware’s “active-LOW” edge logic.

Physical tips: print a black ABS mask or use heat-shrink on the sensor windows to reduce stray light; set sensor-to-disc gap ~0.5–1.0 mm. Start with 1–4 wide slots for cylinder indexing (your firmware maps edges→cyl).

If you must match their exact part

I couldn’t find a published PN from Max Miller or Ethan Crowder in open sources; their public pages reference the mechanism, not the manufacturer part. If you can share a still photo that shows the sensor’s side profile or footprint, I can visually identify whether it’s closer to ITR9608 (square, short body) or TCST2103 (taller, narrow slot) and spec an exact twin. (No guesswork.)

Bottom line

Use ITR9608-F (or TCST2103) + a US Digital HUBDISK (or your STL plastic disc) and you’ll have exactly the “plastic type” optical encoder stack those builds rely on — functionally identical and fully supported by your current PIC firmware and wiring scheme.

ok