JKH not sure where your getting info but the resistance control on the 6970 was not the last version but the cheaper version of the Reactor Control. The 6970 Resistance control was on most Bread and Butter 11&23 UCL Controllers made in the 50's and 60's. 6970 Reactor was still the Premium Operator in 1975 with A Base Solid State Operational and Motion Controllers. I Adjusted them at the Renaissance Hotel at the Renaissance Center in Detroit in 1975 on 1000fpm cars. Watch some of the VVVF control for doors. Some of them when the transistors short they close very fast with nothing to stop them but a circuit breaker which does not always trip.
