The F-28 speed Brake was variable and whilst the Fix-it lever could be pulled at any speed the actual deflection of the Speed Brake doors was proportional to the speed of the Aircraft - around 200Kts springs to mind where the Brakes were fully deployed.
Alas I didn't fly the F70/F100 - a curse I will have to live with! I have heard that they did have the all or nothing feature but that information has been spoiled by alcohol and time.
Lift Dumpers were actuated via a combination of wheel speed generators and micro switches on the mains after touchdown but once again we were able to prove anything is possible if we try hard enough as we had the Lift Dumpers deploy in flight on one occassion. Mr Fokker wasn't pleased!
A wonderful aircraft ahead of its time.
If only Mr Boeing could realise that generators don’t need to be put on line after start, that anti ice systems can operate automatically, speed brakes can actually slow an aircraft down and an aircraft does not have to fly like a D9 bulldozer
Once again a curse I will have to live with!