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Kitcarlson

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This How-To is about converting a sewing machine, for tool battery pack operation. A cordless machine would be excellent for RV use, and for quilt club sewing events. In the past, the idea of doing this was not so practical. Both batteries and motors have improved in performance, a good time to try and evaluate.

 Product development often starts with researching, thinking about scenarios. I enjoy vintage machines, so will start with an aluminum 99K as machine. Original components will not be modified, instead components scavenged from my donor parts bin will be used and modified. The conversion will be installed by removing original hand wheel, belt and motor, then installing conversion components. It is something easily done in a few minutes, like changing to a hand crank.

 My first scenario was to use a portable hand drill motor and battery pack. The drill would be taken apart, gearbox removed, pulley attached to motor, then repackage for mounting. I have a few drills, the best, is one with a brushless motor. A brushless motor has permanent magnets in the rotor and 3 phase windings in stator. Stator windings are driven with rotating electrical signals, where frequency controls speed. Brushless motors seem to make battery packs last twice as long prior to recharge. Being fond of my drills, I decided to purchase a used drill on ebay as donor.

20200129_170345.jpg 
I opened it, a few seconds later discovered speed control attached directly to motor, so repackage not convenient. No loss, drill is like new and works, on to plan B.

I was given a Memory Craft 9000 with seized main shaft. It is from the early 90’s, by the time I got to the main shaft, it was well taken apart. It had many stepper motors, and X Y table for embroidery functions. My wife did not want the machine so it became parts. It has a 24V DC brush motor, very small compared to 110V AC motors. I hooked the motor up to bench top power supply, with variable voltage and current control. The motor was nearly silent, and had good torque, when slowing was attempted with fingers. Current seemed reasonable at 12V and 1A with my crude finger load test, enough to run a 99K. The motor is proven for use in sewing machine and would be a good choice to get started and learn more about power needs.

 20200128_133146.jpg 
The motor is shown in the middle, on left is main shaft drive pulley, on far right the foot control. The drive pulley is hollow, no mass like on a vintage singer. The drive belt is a thin cog belt, providing an efficient non slip drive means. While main shaft pulley is very similar to the 99K in belt drive diameter, the motor pulley ha a small diameter of about 5/16” with a motor to main shaft ratio 8.7:1. A 99K with Singer motor has a ratio of about 3:1. The high torque of DC permanent motor, non slip coupling, plus inertia of high speed motor, hand wheel inertial not necessary.

 20200131_161534.jpg 20200131_161543.jpg  20200131_161523.jpg 

The MC 9000 pulley would not directly work for install on a 99K it would need to be fitted to a Singer style hand wheel. I used a plastic hand wheel from a 70’s vintage Singer Fashion Mate 360. It seemed to share similar features and might mount on 99K with some modifications.

20200202_090616.jpg  

The rear section of the Fashion Mate 360 main shaft was used as holding tool for lathe cut of hand wheel to accommodate MC 9000 pulley section. The pulley section was cut with lathe chuck holding metal insert. The pulley section is presses on for now, later fitting will be checked on Singer 99K, along with possibility of modifications to retain bobbin winding feature.

20200202_130927.jpg 20200201_114655.jpg 

There is a 2lb weight savings in proposed conversion. The battery and charger weigh about 1lb together, so even with them a 1 lb savings. It is unknown at this time if multiple, or larger battery packs will be needed to achieve desired sewing time.

The small circuit under the charger is an arduino nano v3. It is the size of a computer thumb drive. They cost about $2 each in quantities of 10. I have significant experience, using them on various projects. The board, plus a couple transistors, resistors and a diode is all that is necessary to make the speed controller. The MC 9000 foot control has an off resistance of 200 Ohms and full depression of 10K Ohms. It is just a sensor that micro controller measures to determine operator needs. The programming is simple and direct via a USB cable to a PC. When project is complete I will post program file, and circuit details for others to use if they wish.

Next step is to mount motor and test sewing with motor power supplied by variable power supply.  The variable supply will provide data for PWM range necessary for sewing.

20200202_090916.jpg 

The controller program will monitor battery voltage, measure motor voltage and current, interpret foot control, and provide safety for detached foot control.  PC to controller controller communications will be done with common USB to mini USB cable.

The motor was fit to machine for testing machine SPM (Stitches Per Minute) w/o sewing, and current at a few different voltages.   My wife was out, real sewing later, not enough hands to sew, film and take readings.

Motor Voltage   Current    SPM    Est. Watts
   
    5 V                 0.3 A      115       1.5 W
       10 V                0.4 A      300       4.0 W
       15 V                0.5 A      480       7.5 W
       18 V                0.5 A      600       9.0 W

Sewing 2 layers of cotton,  12 stitches/" 
       18V                 0.55 A    580       9.9 W

20200204_162214.jpg 

Here is short movie:


A comparison of running machine, and sewing suggests only about 1 W is required for moving needle cloth and thread. That is much lower than expected.

 I also discovered that motor is very efficient. This idea of using a brushless motor is shelved. The brushless motor requires more parts, 6 large transistors instead of one, and more components to drive them. For this application, not much, if any, would gained in efficiency. Good designs are often simple, so for now using brushed motor.

 I have done research on finding suitable motors, replacement 24 V sewing motors run $50 to $100. I have found a couple similar, surplus medical equipment motors on ebay for ~ $12 each, and purchased for test. I think it may be possible to couple to a potted motor worm gear on a 201.

 Two additional 20V drill batteries and charger for Porter Cable, found inexpensively on ebay. I wanted the charger, for the connector. The connector makes connection to battery, and motor control. It saves work, of fabrication of electrical contact plates, and mechanical mating mechanism.

 Battery protection system (BMS) electronics was investigated. Batteries have on-board system for charge, min and max voltage, and over current protection. Not all batteries are the same, some have BMS parts in charger.

 I am researching DIY battery building from common 18650 li-on cells, and adding battery management boards. For this project sticking with drill batteries (using five 18650 cells and BMS board), for simplicity.

 I sorted my electronics parts stash, getting ready to construct controller.

 A schematic developed and tested with CircuitMaker simulator:

SewMtrCntrl_V1.png

I placed the motor in a Singer Bakelite motor housing.  The wiring compartment will be used for the electronic circuit.
20200216_170436.jpg 20200216_170723.jpg 20200216_171257.jpg 
I didn't have machine when motor was installed in case.  When testing on machine, there was a collision between motor case and arm of machine.  It may have worked if the belt was shorter, but planned to use belt from MC9000.  I changed plan and used bracket made for 1st test and fit and clearance case to fit.
  20200223_153337.jpg 20200223_153352.jpg 
20200223_153645.jpg Circuit is in upper left side of motor case.

It is not as pretty, but with finishing and paint it should be fine.
I started building the electronic circuit.  As suggested earlier, about building and checking a few parts at a time.  I took that further, and only built essential parts, motor control and foot control interface.  Both are very simple.  The additional features including light control, over current protection, current, and voltage measurements can be done outside of circuit, with lab power supply, meters and a lamp.  A third most simple schematic was developed, by deleting parts.

pdf SMCverysimpl.pdf      

 20200223_153755.jpg 
I developed complete software and checked it out for complex circuit, and also revised a simple version for simple circuit.

My first test on the machine was good.  It works as planned.  My wife might test sew with it  in a day or two.

Here is a code snip that shows in software how micro controller reads foot control, and generates value for motor speed control.

#define DetachedVal 0x8f // adc reading above normal control operation when controller plug detached
#define MinControlStartVal 0x10 // adc reading with control depression for start sewing
#define ControlNearMaxVal 0x70 // adc reading when depression near full on, above that PWM max

void MotorControl(void) // PMW control of sewing motor
{
  FootVal = read_adc(); //(0); // read foot controller voltage, assign to FootVal
  if ((FootVal >= DetachedVal) || (FootVal <= MinControlStartVal)) // stop motor
  {
    DDRD.5 = 0; // clear motor pwm pin by setting as input, full off.
    OCR0B = 0; // at 0, PWM duty cycle is 1/128 , so statement above turns pin off
    MotorPWM = 0; // for debug
  }
  else // run motor, vary PWM with foot control depression
  {
     if (FootVal >= ControlNearMaxVal) MotorPWM = 0x7F; // 0x7F is full ON (127 in decimal, 7bit resolution)
    else MotorPWM = FootVal & 0x7F; // avoid possible overflow
    // output PWM
    DDRD.5 = 1; // set pin to output
    OCR0B = MotorPWM;
  }
}

About Program:
Defines at the top assigns names to numbers, for improved reading
Motor only runs for valid window of operation, stopped for pulled foot control cord, and only slight control depression.
When foot control is near full depression, motor is turned full ON, to relieve stress of keeping foot control mashed.

There are other more simple chips in the same Atmel AVR8 family. I plan to build a second controller using a 8 pin chip (ATtiny85) that is about 3/8" square. The code will easily transfer.  The arduino nano was good to start with, program and debug.  The ATtiny 85 is easier to wire up, and is smaller.  I will follow with more details.  It will be something that can be built in a small 0.1" x 0.1" proto circuit board.



My wife sewed using drill battery today. Here is short video. She liked it.


My wife sewed with it for a few days, used a few bobbins, wound them with it. I checked battery voltage, it was 19.3V. Fully charged battery 19.9V. It only took 15 minutes for recharge, on a low current charger. A single battery pack will provide more sewing than can be done at a gathering.

It was warm yesterday so i took time to paint hand wheel and motor.

Attached Images
png SimplContlr2.png (132.37 KB, 6 views)
jpeg 20200304_074242.jpg (208.92 KB, 3 views)
jpeg 20200304_074334.jpg (240.12 KB, 3 views)


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Dave in middle TN

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Reply with quote  #2 
While I can't help thinking, "Didn't we already invent hand cranks for use in an RV?", I definitely like where this thread is going!  I love it when hobbies converge...
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Kitcarlson

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Reply with quote  #3 
It also something to do with electronics, and getting back in. I quit cold turkey on electronics about 3 years ago after starting baby sitting a grandson. Before that, immersed in electronics for 5+ decades. On Saturday my 3yr old gs, picked up an old land phone, and said, "can we take it apart?". He might be ready, so I need to get back. Tomorrow we will investigate the phone.

On Monday I asked grandson if he wanted to look at phone, he quietly said yes.  I gave him a Phillips screw driver, he said, "me do".  He knew where the 4 screws were and tried, I had to help with about an 1/8 turn, to break them loose. He quickly did the rest. We looked over the various capacitors, resistors, transistors, integrated circuit, connectors and switches.  He clearly repeated each word, then told me he wanted to see microphone, I was surprised.  I took the handset apart a showed him the microphone and speaker.  He helped in reassembly, he dropped in all 4 screws and tightened. He was immediately on his way, to play with other toys.

20200203_104100.jpg 
We went from warm and sunny to this:
20200207_074656.jpg 


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SteveH-VSS

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Reply with quote  #4 
Fantastic in every respect.
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JWrobel

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Reply with quote  #5 
First post for me here.  Been lurking for a while.  So thinking about this battery power concept, it occurs to me that many of the earlier electric singers had motors that would run on both ac and dc. So it seems that one could use a Lithium battery of a voltage appropriate to run the original motor, and an electronic foot control for electrical efficiency, and save all the trouble of adapting the machine and motor?
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Reply with quote  #6 
Welcome JWrobel !  Interesting idea
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pgf

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Reply with quote  #7 
A 60 watt sewing machine motor will draw .6A at 100V.   To run the motor for an hour, a 100V battery would need to hold .6 amp-hours.  You can buy a 2.5Ah 100v battery for your Snow-Joe tools for about $210, plus $90 for a charger.  Pricey, and you'd still need to figure out how to connect to the battery.  But it could definitely be done!

https://www.snowjoe.com/collections/100v-ion-cordless-tool-system

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Kitcarlson

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Reply with quote  #8 
A typical triac based electronic foot control will not work on DC. AC has two zero crossings per cycle. Without zero cross (DC operation), machine would start and not turn off.

100V DC for home use could be unsafe.

A 12V to 110V sine power inverter may be better alternative. When voltage in boosted 10x, input current increases more than 10x. So 0.5A load would be greater than 5A from 12V supply. Most power tool packs limit current below that.

Not suggesting the inverter is a good solution, it might work for a few hours if a car battery is used.

https://www.amazon.com/BESTEK-Power-Inverter-Adapter-Charging/dp/B00UFERZKO/ref=asc_df_B00UFERZKO/?tag=hyprod-20&linkCode=df0&hvadid=312158556601&hvpos=1o2&hvnetw=g&hvrand=12813473620935473779&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9013143&hvtargid=pla-493528008903&psc=1



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Reply with quote  #9 
But wouldn't it be fun to run one of those universal motors on DC, just as they were designed to do?  There are lots of resistive controllers around still.  (But you're right that safety is, as always, a concern.)

Anyway, still looking forward to your conversion!

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Kitcarlson

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Reply with quote  #10 
I think the BT7 and PH7 (101 potted motor) were AC/DC motors. They seem to date from 1919 to perhaps 1930. They had a A D field tap plate with screw, for AC, screw at A, for DC screw at D. The D position was extra field turns on one winding, to counteract, it also added resistance. The idea was to make AC and DC operation similar. Later models BR7, and 201 potted motors name plates were AC. I am never at the correct house to check machines, so not sure.

My concerns about safety. Most switches have AC ratings that far exceeded DC ratings. Switching AC clears much better with inductive loads because of zero crossings. DC will draw an arc, contacts need open wider, quicker and even insert insulator. With all that said, 0.6A is not a large current, and switching would be done with machine off, or controller resistance at max.

When shocked with DC it bites, different from the AC tingle. It tends to keep your hand on the tool. When pulling away, tool may go flying.

Shorting a wall plug should trigger a breaker, shorting a 100V battery without fault protection ... very dangerous.

One method of getting 100V - 110V DC would use a variac (transformer with adjustment knob), full wave bridge rectifier and filter capacitor. Adjustment is needed because peak value is greater by about 40%. I don't have a variac. Result may be similar to AC, the variac will make the 60Hz hum, not the motor,  with unfiltered ripple, noise will be at 120Hz.




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Kitcarlson

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Reply with quote  #11 
Additions made to top post showing test currents, and stitches per minute at various voltages, along with short movie running at 600 RPM at 18V.

Added draft of motor driver circuit.

Added to post #3, about grandson.

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Miriam

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Reply with quote  #12 
Just buy a Jackery 500, plug in the machine or use the Jackery to power something else. You still have to plug the Jackery into a power source to recharge. 
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Kitcarlson

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Reply with quote  #13 
Jackery  could power 5 machines,  about a table  full.
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Reply with quote  #14 
Hello Dave,
    You have now shown proof of concept.  I vote you get a 56volt battery powered lawn mower and REALLY make it sew fast......  lol  


Man what a great job!!!  I love that you have taken an option for one trade type and applied it to another!!!  2 thumbs up!!
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Guy,

Wow 56 V! I was thinking of stepping up to 24 V, for the gear driven machines that need a little more power.  I hope to test on a Singer 201 in a week or so.

All,

Thanks for comments, I have updated the end of first post.

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Reply with quote  #16 
Somehow I missed the part earlier about your 3 y.o. grandson taking apart and reassembling a phone (mostly) by himself.  Wow.   You'll be wanting to hide the keys for your treadle bonnets!  :-)
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Reply with quote  #17 
He does like keys. He opens shed where his outdoor toys are kept, and uses key as fake for his car. He is mechanical. I gave him nylon bolts and nuts to play with at about 1 year. He learned those and even practiced with gloves on to get better, his idea.

He has been good about not messing with machines, but eager to crank or pull pins while my wife sews. He is consistent with correct crank rotation.

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Reply with quote  #18 
A more complete schematic has been developed, replacing the early schematic of motor drive circuit.  It is posted at end of first post.  The schematic shows connections to Arduino Nano board.  I have parts on hand to build the board. There are many ways to physically construct and package circuit. At first I thought of using the shell of a Bakelite motor to house motor and control electronics.  I strayed from that, now returning to that idea.  The DC is motor is small enough to fit, and electronics inside too.  The look of machine will be similar to original.  The light plastic hand wheel will be painted gloss black, a flexible LED light mount on motor case.  The whole unit will mount with one screw, and can be easily moved to another machine.

Construction of electronics will be done a few parts at a time, with testing. I will post updates as build and test progresses.

I have started software development, and verified pin settings and actions for PWM signals and analog measurements.  The LED lamp control will have just a single button, with ON, three intensities, and OFF. I have struggled a bit getting back into electronics, has been slow but good.

Tools like CadSoft Eagle for drawing schematics, CircutMaker for simulation and CodeVisionAVR for C-compiler were foreign to me, with use they became familiar.

Please feel free to ask questions about schematic or other things in this project.

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Reply with quote  #19 
Nice job on the motor housing.
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Kitcarlson

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Reply with quote  #20 
Thank you. I reversed housing, the backend required only minor face clearance, where DC motor mounts flush. I felt a bit guilty modifying housing, but have other spares. The Singer motor was a 0.53A, and seemed weak. It was an add on motor to a rough 66.
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Kitcarlson

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Reply with quote  #21 
I revised bottom of top post again with updates.  The controller works!  Hope to do more sew testing this week.
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Added details of controller code snip at bottom of first post.  I also plan to build a second simple controller, easily built with an ATtiny85.  Later I can post the program as text, it can be imported into an evaluation version of CodeVisionAVR.

No time for test sewing today, perhaps on the weekend.

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Reply with quote  #23 
I'm confused:  why does the ADC value go up when you press the foot control?  The controller resistance should be going down, dragging the input closer to ground, no?  I'm also confused as to why the unpressed controller reading isn't in the same low range as the open circuit reading ("DetachedVal").

And...  I never would have imagined having this conversation, or talking about an ATTiny85, on this forum.  ;-)

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Kitcarlson

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Reply with quote  #24 
A good question. The foot control goes from about 200 Ohms unpressed, and 10k pressed. In the circuit the foot control center pin is attached to a 10k resistor that goes to 5V, the outer shell goes to ground. The adc is referenced to 5V, so with supply variations, the reading will be immune. The foot control along with the 10k are a variable voltage divider. Unpressed the voltage is 5x200/(10000+200) about 0.1V, and pressed about 2.5V. If foot control detached, the adc reads 5V.

The code sets a window, so low reading are full off, and a bit above 2.5V is off too. The adc reading happen about every 30 ms, that is real time for human perception. I used a scope to verify operation, the cutoff is perfect, i expected a glitch, but there is none. There is a 0.1uF capacitor that should filter the adc signal, it seems to do well, but possibly over damped. The voltage takes about a second or two to reach final value. I think the control may have a capacitor in it.

My wife will be the true judge, she is in tune with sewing machines, like i am with cars. The value in defines can be adjusted for the machine take-off for smooth consistent start. The 99k vibrates at high RPM, the max PWM can be adjusted too, to keep below that. I considered using the encoder tach, but for simplicity not.

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Reply with quote  #25 
Ah.  I didn't understand that you weren't just using a standard sewing machine foot control, where resistance decreases when pushed.
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Reply with quote  #26 
I am using foot control from Janome, where motor was salvaged. It also has a neat feature of retactable cord. Good for portable use.

.

About the tiny micro. There is also an ATtiny4, six pins. It would work fine, also enough to control light. Shown is 3-pin transistor same size.

Attached Images
jpeg 20200227_084442.jpg (229.42 KB, 4 views)
jpeg 20200227_090538.jpg (402.54 KB, 2 views)
jpeg 20200227_090500.jpg (85.11 KB, 2 views)
jpeg 20200227_090436.jpg (159.21 KB, 1 views)


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Reply with quote  #27 
Do you do your own SMT layouts?  I've done SMT rework at work, when needed, but never for home use.  For home projects I've tended to to use bigger-than-necessary micros,  because they're easier to handle and mount, and they're more flexible, so I only need to keep one type on hand.  And for one-off at home projects, the cost difference between a $1 part and a $4 part isn't really a deal breaker.  (I've used several over the years, most recently the ATtiny44 and ATtiny861.)
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Reply with quote  #28 
Paul,

Good to hear you do electronics too. And avr, that is great!

I use Cadsoft Eagle tool for layouts, I last purchased support around 2010, so not up to date. I think they were bought and upgraded since then. They used to have free evaluation version of limited size board, not sure today. I did layouts for hobby projects like my automotive engine ecu's. When I worked for large companies, there were cad departments, that did that work. There are many details for manufacturing, it takes a village :)

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Reply with quote  #29 
I'm really (or "was" -- retired for several years now) a firmware guy, not a hardware guy.  But I can read enough of a schematic to get by, and to develop the driver.  :-)

My most recent (going back a bit) home AVR projects were to automate the blinds in our bedroom, and put an energy monitor on our electric meter.
https://github.com/foxharp/autoblind#readme
https://github.com/foxharp/irmetermon#readme

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Reply with quote  #30 
Interesting projects!

With most parts being surface mount, I use adapters and smt proto board. It takes some exacto knife, and adding fine wire jumpers. For one of a kind prototypes.

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My wife tested machine today, all went well. Short video at bottom of first post.
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Reply with quote  #32 
Congratulations!   Do you two have actual plans for using your newly portable machine in places without normal power sources?  Or was this all an academic exercise?  :-)
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Reply with quote  #33 
My wife attends quilt guild meeting, they do group sewing classes for techniques, and charitable quilts. She is also doing quilts of valor, with a group.

With multiple machines, there are electrical cords, and outlet strips. A light weight portable, with built-in power source is convenient. It is also smooth and quiet, that helps too.

I am in the process of making a portable rechargable lamp. I have hooks in the motor controller to run a light. Planned to do that, but thought a separate goose neck,could be used for cutting, and sewing. My wife has one she likes, but it powers from a wall adapter. The lamp has a heavy ballast. I will remove that, and replace with li-ion battery pack, along with charge electronics, and regulator.

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I added information about battery usage and added pictures with hand wheel and motor end painted at bottom of first post.  Battery life is much greater than expected.  My next step will be to make a 24V battery and try on the Singer 201K.  The electronics will work with the 20V or 24V batteries.  I have purchased some 18650 sized batteries, and battery management boards to build a battery packs.  I may also build a spot welder to join the batteries instead of soldering.  I will report back when tests are available on the 201k.


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Dave in middle TN
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Kitcarlson

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Reply with quote  #35 
With a few minutes each day, I built a spot welder from parts salvaged from a microwave oven.  The large transformer that stepped up voltage, was modified by replacing the secondary with 2 1/2 turns instead of the original 100.  The transformer is capable of about 500A at 2V, for controlled weld, the transformer is energized for about a tenth of a second.  I was going to build a time controller,  however new controller was found on ebay for only $13.  Welding is done using two electrodes about 5mm distance apart.  Weld current flows from electrode to nickel strip, to battery terminal, then nickel strip and returns to other electrode. Each weld has two spots.  With short weld times, battery is kept cool,  much cooler than soldering.

Most of build of build time was spent constructing electrodes, arms, spring pressure and trigger system.  When pad is depressed, a spring rod pushes the arms down with a force of about 350g on each electrode, and triggers a micro switch for weld start.

20200411_114750.jpg   20200411_130538.jpg20200418_160930.jpg  

My wife likes goose neck LED lamps she purchased from Aldi.  One of them was defective, the wall wart power supply was intermittent.  I could not find a replacement power supply of same class 2 10V 1.6A.  Aldi was great and provided a refund.  I could power the light from my variable bench supply, but that was awkward.

20200418_124903.jpg 20200418_132447.jpg 20200411_085932.jpg 

I decided to replace the plastic covered concrete ballast with batteries, make the lamp rechargeable, use it to power sewing motor and another LED machine light.

Samsumg INR18650-30Q were used, 4S2P configuration.  The battery pack will have about 4 times the energy of single 1.5Ah drill pack. 3M outdoor double stick tape use to adhere batteries and pcb boards.

A battery management system (BMS) was purchased on ebay for about $7 it has electronics that protects battery pack from over charging, over discharge, and equalizes charging of individual cells. Another small board on top is a buck regulator, it efficiently regulates the voltage to 10V for lamp operation.  The lamp also has a USB port, it will power the USB stick-on sewing lamp.
20200418_124924.jpg 20200418_124010.jpg 20200418_123359.jpg 
The middle picture shows LED machine light, it has a control switch for ON/OFF and intensity, it remembers intensity setting.  The right picture shows light under arm of machine.  It has 18 LEDs, and can be cut to length, 5 LEDs were cut off.  The lamp cost was about $6, it works well.

A battery charger was assembled using a laptop power supply and a buck-boost regulator 36140PS purchased from MPJA.com.  It has variable resistors for setting desired charge voltage and current.  It was $6.95.

20200418_125810.jpg Battery charger

Everything thing works as planned.  I will know perhaps in a few weeks how long the battery lasts before recharge.





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Dave in middle TN
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