IRLED Kartı
CompletedA 36-LED infrared illumination board running on 29 V. The control side is galvanically isolated with an optocoupler and the LEDs are switched by a MOSFET.
The board
A long, narrow board I designed for infrared illumination, carrying 36 IR LEDs in a 3 × 12 layout. The LED array runs on 29 V, while the control circuit that switches the board is galvanically separated from the LED power side through an optocoupler.
Circuit
- 36 IR LEDs in 3 parallel strings of 12 in series; each string's current is limited by its own series resistor
- 29 V input: the LED array is fed from a single power line
- Isolation: a VO615A optocoupler carries the trigger signal with no electrical connection between the two sides
- Switching: the optocoupler output drives the gate of an IRLML2502 N-channel MOSFET through a resistor network
- Connections: two separate 4-pin JST PH connectors for power and control
PCB layout
The LEDs sit on a regular grid in the middle of the board; the optocoupler, MOSFET and resistors are grouped at the edges next to the connectors. Traces carrying LED current were kept wide, and there are mounting holes in all four corners.