Hacker News Reader

Comment by jacquesm | Hacker News Reader

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...

View on HN

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.

I use dual gate FETs frequently for all kinds of tricks and they're super useful.

Is that what you had in mind?

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.

Coincidentally, there were vacuum tubes with dual grids for mixer and AGC applications.

And there's someone with a stash of those too. Dual-gate mosfets are one of the ways you know something's been in the back catalog way too long.

Omg... and thinking that my mother throws a huge stash of components like that. my father was an electrical engineer and ham radio. At least, I managed to save a stash of electronic valves and some analog equipment like an old oscilloscope that could be in a museum (I saw a similar model in a museum).

Reply on news.ycombinator.com