This circuit controls resistive and inductive loads up to 2,500W. Its main functional device is an integrated phase control circuit - Siemens TLE3103. It contains its own power supply, a zero voltage crossing detector circuit and a logic driver. An additional feature is the low voltage input to enable/disable triac firing enabling/disabling the logic driver. The function is as follows: pin13 TLE3103 open (floating), trigger output active, tied to ground trigger output disabled.
An UP and a DOWN pushbutton control a 32-step digital potentiometer IC2 (AD5228) via the debouncer IC1 (MAX6817). The digital potentiometer has a power on reset pin which might be tied to ground causing the potentiometer to start at midscale, or to VCC causing it to start at zero scale. The desired function is selectable using jumper JP1. The triac (capable of driving 40A loads) is a bit overkill for the desired power but the BTA41 has an isolated body and therefore handling of the board under voltage is less dangerous as it is with phase on the package. The snubber circuit uses a 68μH inductance but this might be replaced with a 100 resistor. When replacing the inductance C5 should have a value of 47nF.
Board: Purely single sided, measurements: 3.54X2.15 inches (87.63X54.61mm)
Remark: The debouncer circuit is manufactured with a SOT23-6 package. It might be soldered directly onto the board (DIP-6 package) using thin wires or an adapter board.
Part Value Package
Inside a huge PCB factory: https://www.youtube.com/watch?v=_XCznQFV-Mw
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