Back in the 70's my Dad worked for Nikon as part of their Nikon School of Photography and helped out with the Nikon Professional Service. NPS provides equipment and repair support at major news/sporting events. In the early 70's he used to go down to help NPS out at the Apollo launches at the Kennedy Space Center. I got to go with him for one of the last Apollo launches (I recall it was the 2nd one to use the lunar rovers).
Early on my Dad worked with photographers to devise a way to set up remote cames "near" the launch pads (probably a 1/2 mile away). The cameras consisted of Nikon F2's with motor drives and "bulk" backs that could hold 250 frames worth of film (it's the smaller of the two in this photo):
The NASA Press Center was a couple of miles from the launch pad for safety and the remotes would have to be able to fire on their own. My Dad and his friends came up with a great low-cost solution. They went to Radio Shack and bought one of these kits:
It's a "VOX" or "Voice Operated Switch". You use the variable resistor (the white knob near the center) to adjust the noise level threshold that would close a circuit when the noise level was exceeded. It was easy to wire into the motor drive's firing connection. To make the VOX "directional" they took a toilet paper tube, covered it in gaffer's tape, put one end over the round microphone, and pointed the other end towards the rocket.
For security and safety reasons, NASA required that approved remote cameras had to be set up the day before the launch. This meant traipsing around the "nature defenses" of Cape Canaveral (swampy wet lands with aligators, snakes, and some feral pigs), setup up your cameras on tripods with the 50 cent Radio Shack VOX kits strapped to a leg, with the toilet paper tube/mic pointed towards the rocket. If it were a morning launch they were setting up for, they had to hope that the dew would be all burned off before the 3-2-1 came. You never really knew what you got until the film was developed. One of the friends of my Dad's got a very well known photo of the Apollo rocket taking off with a flock of birds flying in the foreground due to the sound of the rocket.