Shopping list, did I forget something? - Page 1
Forum section: electronics / beginners

author: VTKimchi
author_rank: Newbie
timestamp: May 08, 2023, 06:02:31 pm
content: Hello! I have decided to start building my own simple electronics as a hobby, and want to start with something small and (what I hope is) simple to build up my experience and knowledge with various components. I decided I want to use a breadboard to realize the project, so I hopefully can wait with soldering.My goal is to power a vibration motor, with a 9V battery (later a 3.7V LiPo battery) and be able to control the speed of the motor with a potentiometer.I don't know if I need anything else but I went to Digi-key and picked out the components I think I'll need, I would love to get some feedback if this would work or if I need some other components as well.I decided on two different type of vibration motors, coin and capsule(?).This will be a project I want to expand later. But rather than trying to get everything to work at once, I want to have a iterative process where I can experiment first.I already have a breadboard, but the rest I do not. So this is what I have in the cart right now. I picked a few different motors to test with, and two potentiometers to test with.1670-VZ7AL2B1692082-ND- capsule motor1670-VZ7AL2B169208T-ND- capsule motor1670-VC1020B111F-ND- coin motor1738-FIT0774-ND- coin motor1597-1244-ND- coin motor3310Y-001-103L-ND- potentiometerPTV09A-4220F-B103-ND- potentiometer455-2247-ND- 2 pin JST-XH connectorBS6I-ND- 9V battery connectorI want to power this with a 9V battery at the moment, and later find a more suitable LiPo battery. I think a JST-XH connector would work for that, feel free to correct me. But for now I assume I need something more if I want to use a 9V battery instead. So feel free to add to the shopping list, and if possible explain what the component(s) do. I am not sure if the 9V battery connector is suitable for use with a breadboard, so if there are better options feel free to suggest it.Does the list look good, is anything missing, anything I should think about?

author: themadhippy
author_rank: Super Contributor
timestamp: May 08, 2023, 06:19:27 pm
content: More potentiometers ,your going to be burning a lot of them out trying to directly control motor speed

author: VTKimchi
author_rank: Newbie
timestamp: May 08, 2023, 06:32:56 pm
content: Oh, I wouldn't want to burn them out, what could I add to prevent that?

author: rstofer
author_rank: Super Contributor
timestamp: May 08, 2023, 06:36:11 pm
content: With no schematic, I have no idea what you are trying to do but...There is a graph of voltage versus current versus G vibration in the datasheet:https://www.vybronics.com/erm-cylindrical-vibration-motors/encapsulated/v-z7al2b1692082Use your applied voltage (before the pot), figure out what the pot has to drop to meet the current graph in the datasheet. The dropping resistor should be a very low value.If the battery voltage is 3.7V and you want to get to 3V and 150 mA then the pot has to drop 0.7V at 0.15A for a value of about 4.7 Ohms.I only took one example, you have multiple motors of presumably different characteristics so each will need to be considered separately. A spreadsheet seems like a good idea when considering multiple variants.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 08, 2023, 06:39:10 pm
content: The 10k pots are much too high in resistance to directly control motors. And lower resistance ones likely will not appreciate the power dissipated in them.I have looked up the specs of only the first motor you listed and see that the typical current is 180 mA. That is rather high for the 50x25x18 mm size of 9 Volt battery that your battery connector is commonly used with.I think you would do better to start with some LEDs instead of motors.

author: rstofer
author_rank: Super Contributor
timestamp: May 08, 2023, 06:40:21 pm
content: Quote from: VTKimchi on May 08, 2023, 06:32:56 pmP = I2R - The power dissipated in watts is equal to the current through the pot squared times the maximum resistance.0.152* 4.7 = 0.1 Watts - a quarter Watt potentiometer of 4.7 Ohms per my previous example. We're ponly dropping 0.7V. Another form P = E2/R or 0.72/ 4.7 = 0.1 WattsIf you use a 9V battery on a 3V motor at 150 mA, the resistor has to drop 6V and the resistance should be 40 Ohms and the power rating should be 62/ 40 or 0.9W - probably need to buy a 2W pot and it won't be small.That's why we use a uC and PWM to control speed - much lower power loss and a suitable micro might fit in an 8 pin chip.

author: Infraviolet
author_rank: Super Contributor
timestamp: May 08, 2023, 06:55:29 pm
content: I'd tend to recommend a h-bridge chip for motor control. TB6612FNG on a carrier board works nicely. Getting yourself an arduino uno and some 555 timer chips, as well as sets of common resistors and capacitors could be helpful too.

author: themadhippy
author_rank: Super Contributor
timestamp: May 08, 2023, 07:33:35 pm
content: Forget the h bridges oscillators and microprocessor,start with the basics ,a simple single transistor circuit is all ya need,

author: VTKimchi
author_rank: Newbie
timestamp: May 08, 2023, 08:02:32 pm
content: QuoteI want to control the speed of a motor (such as the 3.7V one you looked at) by turning a knob. So it was something I thought wouldn't be too fancy. I am very new to all this, so I might have underestimated the difficulty for what I wanted to try.QuoteI really liked your explanation. I'll see if I can make a spreadsheet for this that take the different requirements into account.QuoteI am actually waiting on a box from Elegoo "The most complete starter kit Uno R3 Project". But I am not sure if it had a 555 timer chip, so I might need to get one of those.QuoteYes, I think microprocessors is a bit above my skill level when it comes to electronics at the moment. It would be fun to look at later, when I have the basics. If I may ask, how would a "simple single transistor circuit" look?QuoteThank you for your explanation it is really helpful! uC and PWM seems a bit to hard for me at the moment, but I'll look into it and see if I can understand it.

author: rstofer
author_rank: Super Contributor
timestamp: May 08, 2023, 08:44:19 pm
content: If you bought the UNO starter kit, there will be a project for controlling a motor with PWM - page 191 here:https://m.media-amazon.com/images/I/C1wMkX1+N9L.pdfthe Motor experiment - it is shown in the table of contentsIt uses a L293D motor driver chipWith the Arduino starter kits, all of the code is provided. It's a great way to get started.The tutorial and code is at:https://download.elegoo.com/01%20STEM%20Kits/01%20Uno%20R3/Super/ELEGOO%20Super%20Starter%20Kit%20for%20UNO%20V1.0.2022.08.04.zipI highly recommend this starter kit and a similar offering for the Raspberry Pi. There's' a lot of education with these kits.

author: VTKimchi
author_rank: Newbie
timestamp: May 08, 2023, 08:45:20 pm
content: QuoteThank you! I will check it out!

author: rstofer
author_rank: Super Contributor
timestamp: May 08, 2023, 08:47:21 pm
content: Quote from: VTKimchi on May 08, 2023, 08:45:20 pmThe Amazon link had a trailing backslash that was bogus. Link corrected.

author: themadhippy
author_rank: Super Contributor
timestamp: May 08, 2023, 09:28:12 pm
content: Quotesomething likebest to add a back emf diode across the motor