Comment by jacquesm
6 hours ago
That's a great exercise. The hard part is always that in chips you can pull stuff that is rather tricky discretely, for instance, a multi-emitter transistor. So you can't always do a 1:1 conversion but for a 555 it is still doable.
I saw this a while ago:
https://www.instructables.com/Designing-a-555-Timer-on-Discr...
Only because odd components aren't marketable. There used to be 4-terminal MOSFETs, they weren't sold after ICs became normal. Never heard of a multi emitter transistor being sold discretely but it's possible.
Dual gate mosfets were a godsend when building RF/IF mixers or preamps. Luckily I have a small stash as they're almost unobtanium and costly these days, but for most uses such as mixers and preamps they can be swapped with a pair or normal jfets in a cascode configuration like this one: https://i.stack.imgur.com/6Nyhg.gif
Today I learned you can build an entire freaking CPU out of 555s lol
https://hackaday.com/2011/08/05/building-a-computer-out-of-5...
> Dual gate mosfets were a godsend when building RF/IF mixers or preamps.
exactly :)
BF901 FTW.
I use dual gate FETs frequently for all kinds of tricks and they're super useful.
Is that what you had in mind?