They put into place things like Congress, the veto, the committee in Congress, and made it pretty difficult to change the Constitution.
There is another aspect of American government that I believe would prevent tyranny of the majority, though it is an accidental or derivative feature, one which seems often to be unappreciated by particular Congresses. It is also one which once unappreciated invites further lack of appreciation in retribution. The idea is that because majority rule in Congress is at best temporary and secure only until the next election, it would be wise not to pass laws that are intolerable to the minority party, so that they do not do the same against you when they become the majority. To do otherwise is to invite a damaging feud or the political equivalence of the nuclear policy known as ‘mutually assured destruction’ (M.A.D. for short, in one of the most apt acronyms ever designed). Unfortunately political groups, here or abroad, are not usually wise in this regard. Or they tend to hold the belief that if they could just get a law on the books it will become less objectionable somehow before the next election. It seems to me, however, unequivocal that if you rule by sheer majority numbers without looking for an acceptable accommodation of the minority, that, if and when they become the majority, they will not try to accommodate you. In that case both sides lose for at least part of the time, instead of both sides having what they need the whole time. With common sense and sensitivity apparently not forced on legislators by nature, nurture, or the ephemeralness of power, it is left to formal voting mechanisms to try to force cooperation.
All of this stuff will work, only if the people are properly informed. Unfortunately, we are not properly informed, because our media has been taken over by Corporations, who have wiggled into the pockets of our politicians, and control both of the only 2 choices we have. All of the “choices” Americans are given come from corporations, and the media than tells America which choice our politicians have taken.
Google Edward Bernays, who was Sigmund Freud’s nephew. He psycoanalyzed people in large groups and figured out how to manipulate how people can think by giving people information you want them to have, rather than people figuring out information on their own.