Schotky diode the keep the base out of saturation ? As used in 74S 74LS, appreciate it's an extra component to bodge in see eg https://electronics.stackexchange.com/questions/242715/using-a-schottky-diode-to-improve-pnp-transistor-turn-off-time Martin
-----Original Message----- From: Christian Corti via cctalk <[email protected]> Sent: 28 October 2025 08:30 To: Jon Elson via cctalk <[email protected]> Cc: Christian Corti <[email protected]> Subject: [cctalk] Re: Replacements for DEC 3639 On Mon, 27 Oct 2025, Jon Elson wrote: > I have used its NPN mirror (MPSH10) in switching circuits and they > work quite well, giving ~1ns 10-90% rise and fall. I have not used > the MPSH81 Rise/fall times are not the problem. The problem is the huge delay of over 100ns due to the storage time. Christian
