When you get to be my age, you will store your small parts in pill bottles, not envelopes. Also, when you get to be my age, it helps to label your parts immediately upon salvage. Another point about the porcelain isolator, is that it will dissipate heat generated by the variable resistor type switch that it is. A factor that is minimized in electronic type switches.
Excellent example of the old "carbon stack" foot pedal. I also save old parts for many of my hobbies. Silentlly causing my family to talk of a possible hoarding issue. However, I would like to explain the function of the carbon discs. When the foot button is pressed, the pressure increases to the disc stack reducing the space and the resistance between the discs causing an increase in the voltage and current to the motor. ( Ohms Law - P=I×E and E=I×R ). The problem of controlling motor speed, 100 years ago, was solved with this foot pedal design. It worked with all of the different types of voltages, AC/DC 30 to 110. But the result is heat generated at lower speeds due to the higher watts or heat going into the carbon discs. NOTE: This is the reason you must always unplug a carbon stack controller when not physically using it. The possibility is the disc stack generating maximum heat at the slowest speed and at "no speed", if it malfunctions or is out of adjustment. Imagine a wall dimmer switch that does not have a smooth increase to the light fixture. Would you attempt to fix that switch, or replace it? The carbon discs get worn out causing carbon powder and disc breakage. Both of these cause an increase in current flow. The motor speed is also increased by the increased voltage supplied by your power company. Voltages above 130VAC are not uncommon. This was initially engineered to be 110VAC. [ Another infrastructure topic for later ] Carbon discs controller are amazing. But they also hard to adjust, and sometimes a source of damaging heat. The best solution is to use an electronic foot pedal in place of the carbon disc controller. I have tried rebuilding several pedals and it is not generally worth the effort with worn out discs. I use a analog multi meter to check for a smooth transition from slow to fast. DISCLAIMER: ( I have extensive Training on electronic repairs. So if you dont know what I have been talking about, please have a qualified person replace your foot pedal).
When you get to be my age, you will store your small parts in pill bottles, not envelopes. Also, when you get to be my age, it helps to label your parts immediately upon salvage.
Another point about the porcelain isolator, is that it will dissipate heat generated by the variable resistor type switch that it is. A factor that is minimized in electronic type switches.
Excellent example of the old "carbon stack" foot pedal. I also save old parts for many of my hobbies. Silentlly causing my family to talk of a possible hoarding issue.
However, I would like to explain the function of the carbon discs. When the foot button is pressed, the pressure increases to the disc stack reducing the space and the resistance between the discs causing an increase in the voltage and current to the motor. ( Ohms Law - P=I×E and E=I×R ).
The problem of controlling motor speed, 100 years ago, was solved with this foot pedal design. It worked with all of the different types of voltages, AC/DC 30 to 110. But the result is heat generated at lower speeds due to the higher watts or heat going into the carbon discs.
NOTE: This is the reason you must always unplug a carbon stack controller when not physically using it. The possibility is the disc stack generating maximum heat at the slowest speed and at "no speed", if it malfunctions or is out of adjustment.
Imagine a wall dimmer switch that does not have a smooth increase to the light fixture. Would you attempt to fix that switch, or replace it?
The carbon discs get worn out causing carbon powder and disc breakage. Both of these cause an increase in current flow. The motor speed is also increased by the increased voltage supplied by your power company. Voltages above 130VAC are not uncommon. This was initially engineered to be 110VAC. [ Another infrastructure topic for later ]
Carbon discs controller are amazing. But they also hard to adjust, and sometimes a source of damaging heat.
The best solution is to use an electronic foot pedal in place of the carbon disc controller. I have tried rebuilding several pedals and it is not generally worth the effort with worn out discs. I use a analog multi meter to check for a smooth transition from slow to fast.
DISCLAIMER: ( I have extensive Training on electronic repairs. So if you dont know what I have been talking about, please have a qualified person replace your foot pedal).
Thanks! Good explanation; good closeups! I'd have to leave that bad boy intact, and store it like that, so I didn't forget what goes where.
Interesting! It looks like the prototype for an electric mouse trap.🐁
I really enjoyed sewing with a knee controller on my Mom's old Elna when I was a kid.