Notes on Mechanical Devices for the Electronics Experimenter - Revision history

Marcin: /* Summary */

2018-08-13T17:47:02Z

Summary

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	== Summary ==		== Summary ==
	I got this book because I don't know much about mechanical engineering and this seemed like a great intro.		This is the title of a book. I got this book because I don't know much about mechanical engineering and this seemed like a great intro.

	The introduction says it's meant for amateur experimenters to get a good foundation for experimentation and measurement and build by designing<=>building<=>testing.		The introduction says it's meant for amateur experimenters to get a good foundation for experimentation and measurement and build by designing<=>building<=>testing.

Alexau: /* Ch 7: Gears and pulleys */

2018-08-07T17:22:27Z

Ch 7: Gears and pulleys

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	== Ch 7: Gears and pulleys ==		== Ch 7: Gears and pulleys ==

			=== Belt Drives ===
			When you create a machine, you want 1 source of power, and then you want to distribute that power in various ways to different elements to make the system perform work.

			So gears and pulleys give you more ways to not only translate the direction of power and its location, but also to amplify the power through mechanical advantage.

			Here's 4 different gear/pulley systems:
			* Wheel drive - wheels spin each other
			* Gear drive - gears spin each other
			* Belt drive - a belt connects two wheels, that spin each other
			* Chain and sprocket drive - a chain connects two gears, that spin each other

			There's a bunch of rules on page 85 for how to design belt drives.

			There's also a diagram of how to make a belt.

			=== Gears ===
			There's ALOT to design about gears. Here's something that's notable to understand about why their design is so complex:

			* if you have a gear A
			* you must have a different design gear B for it to rotate on A
			* if you have a gear C that "meshes" with gear A
			* then generally speaking, gear B and gear C WILL NOT mesh together
			* But... it is possible to design "tooth profiles" where all the gears can mesh with each other

			Although gears lose a little power to friction, you can stack them and increase your mechanical advantage.

			In a Black and Decker Model 9072 cordless power screwdriver, it's handheld but has a mechanical advantage of 81 for like-woah torque.

			Keep in mind that you can have a shaft of a gear be the axel for another gear, which, when connected to another gear, has the lever thing happening.

	== Ch 8: Other mechanical stuff ==		== Ch 8: Other mechanical stuff ==

Alexau at 17:11, 7 August 2018

2018-08-07T17:11:21Z

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	Apparently these are often used in motors.		Apparently these are often used in motors.

			== Ch 7: Gears and pulleys ==

			== Ch 8: Other mechanical stuff ==

Alexau: /* Solenoids */

2018-08-07T17:02:12Z

Solenoids

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	=== Solenoids ===		=== Solenoids ===
			This device transforms electrical energy into mechanical energy. Here's how it works:

			* there's a hollow cylinder
			* there's a coil wrapped around it
			* there's a magnetic plunger that fits into the cylinder
			* when you energize the coil, the plunger will be pulled into the cylinder
			* then you de-energize the coil
			* a spring can return the plunger to its starting place (hanging at the edge of the cylinder poking out)

			ToDO: Add picture

			Apparently these are often used in motors.

Alexau: /* Stepper motors */

2018-08-07T16:57:48Z

Stepper motors

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	=== Stepper motors ===		=== Stepper motors ===
			When I imagine a motor, I think of it as just either running or being turned off.

			Apparently, there's such a thing as a stepper motor, which has more states that it can be in while it's turned on.

			Because you can control it's state while it's turned on, you have more control over the timing for when power is being generated.

			There's 3 types of stepper motors:
			* permanent magnet
			* variable reluctance
			* hybrid

	=== Solenoids ===		=== Solenoids ===

Alexau: /* Motor control */

2018-08-07T16:55:25Z

Motor control

← Older revision		Revision as of 16:55, 7 August 2018
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	=== Motor control ===		=== Motor control ===
			There's different circuit diagrams for different systems of controlling a motor.

			It seems like if you have a steady voltage, and you want to adjust the current to adjust the work, the thing you control is resistance.

			By using a "variable resistor" or an uninjunction transistors, you can control the resistance and therefore the current.

			Not really sure if this is how it works because I did not read this chapter.

	=== Stepper motors ===		=== Stepper motors ===

	=== Solenoids ===		=== Solenoids ===

Alexau: /* Motors */

2018-08-07T16:51:53Z

Motors

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	=== Motors ===		=== Motors ===
	A motor acts a bit like a generator, which means it generates an electric field.		A motor acts a bit like a generator, which means it generates an electric field (and therefore also a magnetic field, bc the 2 are intertwined)

	Curiously, the polarity of the motor, which I believe is a magnetic property, is something that "lowers" the voltage of a motor.		Curiously, the polarity of the motor, which I believe is a magnetic property, is something that "lowers" the voltage of a motor.

Alexau: /* Motors */

2018-08-07T16:51:24Z

Motors

← Older revision		Revision as of 16:51, 7 August 2018
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	=== Motors ===		=== Motors ===
			A motor acts a bit like a generator, which means it generates an electric field.

			Curiously, the polarity of the motor, which I believe is a magnetic property, is something that "lowers" the voltage of a motor.

			Not really sure how voltage of a motor translates into its capacity to generate power or work or joules.

			Did some research and you can look more info on that here: [https://electronics.stackexchange.com/questions/39387/how-are-current-and-voltage-related-to-torque-and-speed-of-a-brushless-motor How are current and voltage related to torque and speed of a brushless motor?]

			Basically: V = E + IR \|OR\| V = IR - E depending on the motor type, where V = voltage, E = internally generated voltage generated by magnetism, I=current, R=resistance.

			Voltage is the difference in charge between 2 points.

			Current is the rate at which charge is flowing.

			Resistance is a material’s tendency to resist the flow of charge (current).

			[https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law Voltage Current Resistance and Ohm's Law]

			So as it turns out, torque of a motor is related to the current, so if you increase the voltage, you increase the work (torque) done by the motor.

	=== Motor control ===		=== Motor control ===

Alexau: /* Sensors and control */

2018-08-07T16:39:10Z

Sensors and control

← Older revision		Revision as of 16:39, 7 August 2018
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	=== Sensors and control ===		=== Sensors and control ===
			There's open-loop control and closed-loop control.

			Open-loop control: you have a theory of what will happen, and then you command the machine to act accordingly. Then it does its best.

			Closed-loop control: After the machine acts, there's a measurement of what is actually happening. This feedback returns to inform the input about what the machine should actually be doing.

			Position sensing: you can see how many times a gear has turned by using light and a hole in a wheel to track its revolutions, or derivative measuring systems.

	=== Motors ===		=== Motors ===

Alexau at 16:30, 7 August 2018

2018-08-07T16:30:27Z

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	TODO: add picture		TODO: add picture

			== Overview of Chapters not-relevant to building lasers: 2-6 ==
			I did not read these chapters carefully but only skimmed them for a sense of what is important to robot builders and to familiarize myself with more mechanical things and also to know where I might look if I needed to know these things in the future.

			Here's the chapter list:

			(#2). Sensors and control

			(#3). Motors

			(#4). Motor control

			(#5). Stepper motors

			(#6). Solenoids

			=== Sensors and control ===

			=== Motors ===

			=== Motor control ===

			=== Stepper motors ===

			=== Solenoids ===