Hi, I have a schematic for ultrasonic preamp@471 kHz . Vin is 20mv p-p and supply voltage is 5V. but non of these transistors are available in SMD. any suggestion for a equivalent from this century? with SMD package.
NXP has various SMD, e.g. maybe BFS17 or BF840 might be roughly comparable to a BF494..
For BF256, there are many popular N-ch RF devices, e.g. MMBF5484.