5.6 V Zener, 1 W — the workhorse voltage reference
The 1N4734PE3/TR12 is a 5.6 V zener diode from Microchip Technology in the industry-standard DO-41 axial package. It dissipates up to 1 W, which means it can handle a steady 178 mA at the nominal voltage before hitting the power limit — enough for a simple shunt regulator or a voltage clamp on a 5 V rail. The ±10% tolerance on Vz is the standard commercial grade; the actual zener voltage for any given part will fall between 5.04 V and 6.16 V. For a precision reference, you would reach for a tighter-tolerance part, but for clamping a logic supply or providing a crude bias rail, this is the one you keep in the kit.
DO-41 axial — field-service friendly
The DO-204AL (DO-41) axial-lead package is a through-hole part. You can swap it on site with a basic iron and solder sucker — no hot-air station, no paste stencil. The banded cathode end is clearly marked, so orientation is obvious even under a worklight. The 5 Ohm maximum zener impedance (Zzt) means the regulation slope is moderate; expect the voltage to shift a few hundred millivolts as the current changes from 10 mA to 100 mA.
Microchip lists this part as Active in production. That means no last-time-buy clock ticking — you can design it into a new BOM today and expect to source it for years. The Tape & Reel packaging (TR suffix) is the standard reel format for automated insertion; the base product number 1N4734 is shared across the family, so the same die is available in bulk or other reel quantities.