In NGE AND AAC you pay 5 for a tech roll. On a 6 you receive a random technology.
The AAR version tried to make technology less random. You could choose which technology to roll for. Heavy Bombers were downgraded, while Industrial Technology was replaced by Destroyer Bombardment. This allowed an exploit, where the Germans spend all the cash on Long-Range Aircraft research, with a good chance of successfully capturing Britain on the first turn. To prevent this, technology was made effective at the end of the turn.
In AA50 you purchase researchers for 5 IPC's each. Each researcher succeeds on a 6. Once any researcher succeeds, you get to choose to roll on 1 of 2 technology tables (one land oriented, one sea/air oriented), after which all your researchers are discarded. The techs are reduced in power.
In AA42 technology was removed entirely.
All the technology rules have the fundamental problem of introducing a highly random element into a game of strategy. In addition, most technologies benefit the nations who have more resources, throwing the balance even further against struggling nations.
To reduce the randomness of technology you can try Reduced Luck Technology, Low Luck for Technology or Technology Bidding
In TripleA technology is controlled by the following properties