Simple 9V battery-powered NE555 astable LED blinker with on/off switch, red indicator LED, and hand-solder-friendly through-hole components.

Competition PCB for a to and fro memory robot using through-hole components only. Target layout is maximum 120 mm x 70 mm, 2-layer maximum with top-layer routing only, 0.5 mm trace width minimum design intent, 0.3 mm clearance minimum, restricted solder mask outside the board center, and manufacturing freeze before 15 April 2026. Planned architecture uses a simple 5 V control and drive system with sensor inputs, memory/control logic, motor-driver stage, user controls, and edge-access debug/test points.

Hand-solderable 9V battery-powered red LED blinker using a 555 timer astable circuit, on/off switch, and through-hole support components.

9V battery-powered 1 Hz red LED blinker using a through-hole 555 astable timer, on/off switch, and hand-solderable components.

DIP-20 is a through-hole package with 20 pins arranged in two rows spaced 7.62mm apart. The body of the package is typically 27.94mm long and 10.16mm wide. DIP-20 is commonly used for a variety of integrated circuits and other electronic components. 20-DIP #part #template

DIP-20 is a through-hole package with 20 pins arranged in two rows spaced 7.62mm apart. The body of the package is typically 27.94mm long and 10.16mm wide. DIP-20 is commonly used for a variety of integrated circuits and other electronic components. 20-DIP #part #template

DIP-20 is a through-hole package with 20 pins arranged in two rows spaced 7.62mm apart. The body of the package is typically 27.94mm long and 10.16mm wide. DIP-20 is commonly used for a variety of integrated circuits and other electronic components. 20-DIP #part #template

Through-hole 9V battery-powered 555 timer circuit that blinks a red LED approximately once per second using an on/off switch and hand-solderable components.

Through-hole 9V battery-powered 555 timer circuit that blinks a red LED approximately once per second using an on/off switch and hand-solderable components.

Resonate Pendant golden reference design. Board is a 39 mm x 63 mm portrait rectangle with 5 mm corner radii, 2-layer FR4, 0.8 mm thickness, 1 oz copper on both layers, matte black top solder mask, no bottom solder mask, ENEPIG finish, and no silkscreen on either side. Allowed components only: U1 STM32L052C8T6, U2 CH340E, U3 BQ24210DQCT, C1 10uF, C2 4.7uF, C3-C7 100nF, R1 24k, R2 1k, R3 10k, D1 green 0402 LED, MAG1-MAG4 magnetic pads, J1 solar solder pads, J2 battery solder pads, TP1-TP4 test pads. Required top artwork: golden-ratio grid lines and gold circles on F.Cu with mask openings, decorative only, 0.8-1.0 mm width, at least 0.5 mm from active traces. Required bottom artwork: exposed ENEPIG bottom copper split into FREQ_OUT 61.8 percent and GND 38.2 percent with an exact 0.20 mm S-curve isolation gap, no vias through bottom except one PA4-to-FREQ_OUT via at the extreme edge. Functional requirements: MAG1 and J1 VIN feed U3 IN, U3 OUT feeds J2 battery pad and system VBAT, MAG2 to U2 UD+, MAG3 to U2 UD-, MAG4 to common ground, U2 TX to U1 PA10, U2 RX to U1 PA9, U1 PA4 to bottom FREQ_OUT, U1 PA5 to R2 then D1 to GND, U3 ISET to R1 to GND, U3 TS to R3 to GND, decoupling exactly as specified. Prohibited items: external crystal, JST connectors, wireless module, antenna, separate regulator IC, ESD protection IC, USB-C connector, through-hole parts, bottom solder mask, silkscreen, more than three ICs, or any unapproved substitutions.

DIP-20 is a through-hole package with 20 pins arranged in two rows spaced 7.62mm apart. The body of the package is typically 27.94mm long and 10.16mm wide. DIP-20 is commonly used for a variety of integrated circuits and other electronic components. 20-DIP #part #template