Availability & Target Pricing: One Channel Wider in Its Own Body
Shenzhen Spot Stock (24-48h Dispatch)
Electrical & Core Specs: The eight-channel sibling of the same Darlington class: the same 50V / 500mA per-channel outputs and clamp diodes with the 2.7k input network, one channel wider and four pins longer.
Same output envelope; the COM pin moves with the wider body.
Compatibility & Drop-In Notes: Channel count is the package: 18 pins against 16, not a designed replacement - but the pin functions do align. Leaving pin 1 and pin 18 (the eighth channel pair) out of a 16-pin socket maps channels 1 to 7 one for one, which is the documented bench hack; the designed answer remains the wider part on its own layout, and the eighth channel exists for stepper and multi-relay duty.
Package & Solder Footprint: DIP-18 against DIP-16: one position wider by construction - pins 2 to 17 land where the 16-pin socket expects 1 to 16.
Shenzhen Warehouse Stock & MOQ: Universal stock; the eight-channel default of the relay-driver world.