Guys,
This type of motor starter was very common (I did a quick edit here, how time passes! make that) 40 years ago. Also there were many part-winding, two speed, 2-winding, Y-Delta motor circuits and starters, wound-rotor motors, eddy-current clutches, and even AC motors shaft-coupled to a DC generator, which in turn powered a DC motor, all for some type of speed or torque control! The reason some of you have never seen this circuit can be summed up in 3 letters: V.F.D. The variable-speed and variable-torque motor drives really made motor control a LOT easier, and made circuits like this one kind of obsolete. In 10 more years there will be no one who even recognizes what it was.
As for building-your-own, that used to be pretty common too. In the old days, off-the-shelf equipment was not readily available on short notice. This was before the days of nationwide UPS and FedX delivery service. It used to take 5 to 6 weeks to get something like a two-speed motor starter delivered from the factory. The process was long and slow. First you wrote out a purchase order and had your typist type it up on a manual typewriter. Then you checked it over for errors and mailed (by snail mail, Email was not invented yet) it off to the supplier. He gets your letter, writes out an order receipt, sends the order to the factory, and sends you a letter back telling in how many weeks you can expect shipment. Many times you just had to make do with what your local distributor had in stock or could get from the next town.
This type of motor starter was very common (I did a quick edit here, how time passes! make that) 40 years ago. Also there were many part-winding, two speed, 2-winding, Y-Delta motor circuits and starters, wound-rotor motors, eddy-current clutches, and even AC motors shaft-coupled to a DC generator, which in turn powered a DC motor, all for some type of speed or torque control! The reason some of you have never seen this circuit can be summed up in 3 letters: V.F.D. The variable-speed and variable-torque motor drives really made motor control a LOT easier, and made circuits like this one kind of obsolete. In 10 more years there will be no one who even recognizes what it was.
As for building-your-own, that used to be pretty common too. In the old days, off-the-shelf equipment was not readily available on short notice. This was before the days of nationwide UPS and FedX delivery service. It used to take 5 to 6 weeks to get something like a two-speed motor starter delivered from the factory. The process was long and slow. First you wrote out a purchase order and had your typist type it up on a manual typewriter. Then you checked it over for errors and mailed (by snail mail, Email was not invented yet) it off to the supplier. He gets your letter, writes out an order receipt, sends the order to the factory, and sends you a letter back telling in how many weeks you can expect shipment. Many times you just had to make do with what your local distributor had in stock or could get from the next town.
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