Enabling Seamless Real-Time Data Transmission for Pulse Oximeters: A GPRS-Based Attachment with Offline Connectivity

230 VAC to 5 V non-isolated offline buck using Power Integrations LNK3204D. Every net, including HAZ_5V and HAZ_RETURN, is hazardous live/mains-referenced; sealed internal use only with galvanically isolated test and programming equipment.

Secure offline password manager using Arduino Pro Micro, MB85RC256V F-RAM, detachable Nokia 5110 LCD, rotary encoder, and 3.3 V support circuitry.

Industrial 24 V DC MESBox controller with embedded Linux SOM, STM32 real-time I/O, triple RJ45 Ethernet, TFT display, isolated inputs, protected transistor outputs, offline memory, surge/reverse-polarity protection, and EMC-focused layout constraints.

Unconnected DER-920 65 W offline LED ballast component schematic grouped by input/EMI, PFC boost, isolated flyback, secondary control/dimming, and connectors. Components are intentionally not wired yet.

300 W universal-input isolated offline SMPS based on a modified ATX-style architecture. Universal 115-230 VAC, 50/60 Hz input via fused IEC C14 inlet. Outputs: +12 V at 20 A, +5 V at 14 A, +3.3 V at 12 A, +5 Vsb at 2.5 A, and -12 V at 0.3 A. Includes primary rectification with GBU806 bridge, bulk capacitors, bleeders, snubbers, main PWM and driver transformer, standby flyback, optocoupler and TL431 feedback, supervisor logic, test points, fan and heatsink provisions, and 2-layer FR-4 PCB layout with 8 mm primary-secondary isolation and heavy copper routing on high-current rails.