A History of World Lighting Control pre-1960

"liquid dimmer....judicious adjustment of the quantity of salt could be made to handle almost any required load..." Good to know.

The only time I came across a working resistive dimmer was at a historic meeting hall. It had a label with a wattage range.
 
Thank you Steve for findi g this gem. I have to say I found the Q&A most interesting as similar conversations happen today.
 
"liquid dimmer....judicious adjustment of the quantity of salt could be made to handle almost any required load..." Good to know.

The only time I came across a working resistive dimmer was at a historic meeting hall. It had a label with a wattage range.
I grew up on resistance dimmers. First used Saltwater dimmers on a March of Dimes presentation tour in the late '50's, then later piano boards of 14 3,000w resistance plates and a locking main shaft. Most shows had one electrician for every two piano boards sitting face to face. A large show might have 6 to 8 (sometimes more) piano boards for 84, 108 or more dimmers for a large musical. Part of the LD's job was to design circuiting/dimmer allocation so that no one electrician had to do all the dimmers in a single cue. One became an acrobat to do some cues. We had 3 and 4 dimmer "boards", an actual pine board that was about 18" to 30" long and spanned 3 or 4 dimmer handles so you could move adjacent dimmer handles at once. For a large fade up or down, all the dimmers moved together if they were on the main shaft so you might have a 3 dimmer board balanced on a knee moving up ( couldn't fade down with your knee), 7 or 8 dimmers locked into the shaft moving up or down and maybe 1 or 2 singles moving different directions. As the dimmers on the shaft reached the desired setting you'd "drop" them off, a quick twist of the handle to release the shaft, sometimes but rarely lock one in as you went by, When the cue was finished you would go back and nudge individual dimmers as needed to the exact desired setting as fast but as subtle as possible. A piano board was abou 7' wide, 4'-5' tall and about 42" deep at the base. There was a noticeable amount of effort needed to move 5 or 6 dimmers at once. So after 60 - 80 cues on a Musical, you were tired. If the show hac a lot of low light level scenes you were also very hot and sweaty. For those of you that don't know, a resistance dimmer dims the light by transforming a portion of the current into heat. The brighter the stage light, the less the heat, the dimmer the light the greater the heat in the control room. In the summer we ran most shows in shorts and no shirt. Patching was by pushing or pulling stageplugs (a 2 1/2" to x 5" slab of bakelite with 1/2" to 7/8" wide exposed copper strips down each side) in and out of the 2 1/2"x 1 1/2" open porcelain receptacles across the top of the board, each of which could accommodate 2 half plugs or one full plug. Anyway, history 101 is over.
 

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