Table Saw Soft Starter With Option Output

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Introduction: Table Saw Soft Starter With Option Output

About: Hi, i'm electronic technician but it's my hobby too. I like to do and try many projects just for fun :)

Hi, this is my new project. A Table saw soft starter with option output. This means, when you have something to cut with a table saw or miter saw or any power tools. This module detect when the load is turned on and send voltage from low to high in 3 seconds. It remove the huge spike at the beginning, lower startup current and very more quiet. No more breaker problem at startup. Very handy with generator. Some generator have limited startup current.

I have also added a second output to plug a vacuum, light or anything else. This output have different options. It can start at the same time of the saw or after. It can be soft start or hard (direct) and can also stop 6 seconde after saw has be turned off. These options can be chosen by connecting some pin to gnd.

So if i resume, you plug the saw (turned off) in saw outlet. You plug the vacuum (turned on) in vacuum outlet. When you turn on the saw, the saw will start slowly. As your option switch setting, the vacuum will start by itself. No need to turn this on. The module will send the voltage for you. When you will turn off the saw, the saw will turn off (of course) and the vacuum too. No need to touch at the vacuum anymore.

I was searching for this on internet. I found different soft start but some modifications was needed on the table saw. Like cut the power button to bypass the switch. I wanted something transparent. I finally found a module but without option output. You can see this module here. By the way as you can see the girl is very pretty :P On my side i dont have some pretty girls and Ferrari (see behind) to do my demonstration but at the end, it's doing exactly the same :)

ADVANTAGE:

0v ac to 115V/230V in ~ 3.2 sec

2 Outputs: Saw and Vacuum

Output 2 can be soft, hard, start and stop delayed

115V/230V same pcb, Only 1 layer pcb.

1 universal software for both version (115v,230v)

Device can Hold up to 25 Amp. (Triacs)

No external modification needed on saw

Board fit in a conventional electric box

Disadvantage:

Lost of approx 2v rms at the output. The triac are not like relay. it's not a mechanical contact.

Step 1: So Let's Begin. the Schematic.

I give you the image and pdf version.

There are 5 areas.

- The uC atmega328 is the controler for this projet. i'm using 3% of memory only. Why i choose a 328 instead a simple tiny ? Because those one are very very popular and cheap. Buy a arduino and you will get an atmega328. But i'm not coding with arduino ide. I'm using atmel studio.

- The Power supply. Nothing more that a regular linear psu. Bridge regulator et lowpass filter.

- The 0 crossing detector. When we work with ac and triac. We must know when remove the trigger on the triac.

this is the job of H11AA1. This one send a pulse to uC when 0v is achieved.

- The current sensing module. We must know when we power on the saw. This is the job of the CSE187L

when a current pass throw the transformer, a voltage is coming at the output. Diode, lowpass and the zener 5.1v ensures that voltage will not cross higher than 5v.

- Output modules. optocoupler and triacs are limiting the current to the load.

Step 2: The Parts.

As you can see on picture, there are no very much parts. All those parts aren't obsolete and can be easily buy on digikey, mouser or even ebay.

This is the list: At the end is the digikey PN of the main component

B1 Bridge rectigier DF02MDI-ND

C1 0,02uf

C2 100uf 25v

C3 33uf 10v

C4 .1uf

C5 0,02uf

C6 .1uf

C7 1uf

D1 Zener 5.1v 1N5231B-TPCT-ND

D2 1N4148 1N4148FS-ND

IC1 ATMEGA328P ATMEGA328P-PU-ND

IC2 7805TV 497-1443-5-ND

LD1 LED5MM

LD2 LED5MM

OK1 H11AA1 H11AA1M-ND

OK2 MOC3021M 160-1374-5-ND

OK3 MOC3021M 160-1374-5-ND

R1 1k

R2 33k

R3 220

R4 150

R5 1,2k

R6 2.2k

R7 220

R8 150

R9 1,2k

R10 33k (removed in version 1_1)

R11 1M

T1 BTA24 497-3124-5-ND

T2 BTA24 497-3124-5-ND

T3 FS12-090-C2 237-1577-ND

T4 CSE187L 237-1103-ND

You will need electrical boxes. So buy 2 and attach both boxes together. But at the beginning it's easier to have them split up. More easier to fix the board in place.

Also some wire. I recommend 18 awg for psu and 14 awg for triacs

Step 3: PCB, Gerber File or DYI Method

I'm giving you 2 choices. A diy PCB like i did. It's only 1 layer, no big deal. Or you can use gerber file to have a professional pcb. The .zip is gerber file. This file you need to upload to pcb manufacture. You can see the final result by uploading the file here

The gerber file isn't the same than diy pcb. There 2 layers for triac. Also trace space are a bit higher between each other.

For the DIY method i prefer the toner transfer method.

Impossible to upload gerber file. Internal server error so...

Gerber Files here

Step 4: Solder Component

As you can see, i added solder on pcb large wire. The current will be higher on those wire. It's also time to solder the larges wires. 18 awg for psu and 14 for triacs.

Step 5: Program the Atmega328

Plug in your USBasp or USBtiny device in your computer and let Windows detect the device (it will report driver not found). If a window pops up asking to search for driver, just close it or click on Cancel.

At this point, download and run Zadig, it should detect the USBasp or USBtiny, or any libusb device that you have. Then in the selection box (see picture), choose libusb-win32 (v1.2.6.0), click on Install Driver, and wait for the installation to complete. Check in device manager for atmel usb device = ok. No excalmation mark anymore Download SoftStart_code below on this page and unzip files in a folder. I create a batch file to program the chip with .hex and fuses bits at same time. Connect USBasp or USBtiny cable in your board, no need to plug the softstart in wall. Double click on program usbxxx.bat At the end, code and fuse bit are programmed.

You can use atmega328 or atmega328p.

Step 6: Preparing the Box

Remove the 4 screws. We will reuse those screws later. Put some nuts as spacer and add some plastic sheet (like picture) or if not, probably some electrical tape should be ok but try to find some plastic isolator first. Maybe on an old power supply. That's what i did.

Gangable electrical box.

https://www.homedepot.ca/product/iberville-device-...

https://www.rona.ca/en/device-box-gangable-2-1-2-0...

Step 7: Bent Triacs, Thermal Paste

You need to bent a bit both triacs and add some thermal paste. With only a half of electrical box, fix the board and triacs. You will need to do 2 holes for this.

The triacs doesn't need to be insulate. BTA24 are stock insulate.

Step 8: Option Wires

4 little wire to connect the option switches. The option switches are optional.

If you add no jumper at all default of out 2 is: Soft start, delayed start and stop at same time of out1.

See next step for more details

Step 9: Install Outlet and Option Switches

With schematic help, install outlet. Be careful to put the Hot at the right spot. Connect also the ground earth to the outlet.

Important. You must disconnect outlet from each other by removing the tab between the outlet. See picture. Only hot side need to cut.

Like i said, The option switches are optional.

Options.

Pin1(pb4) to gnd = Out2 will start after Out1

If not = Out 2 will Start at same time of Out1

Pin 3(pb5) to gnd = Out 2 will Hard Start

if not = Out 2 will Soft Start

Pin 4(pb3) to gnd = Out 2 will continue 6 seconde after.

if not = Out 2 will stop at same time of Out1

If you add no jumper at all default of out 2 is: Soft start, delayed start and stop at same time of out1.

Step 10: Is a 15 Amp Breaker Is Enough ?

A saw consume a lot of current. You can see here a full table saw review including amp current.

https://www.toolboxbuzz.com/head-to-head/best-port...

as you can see, it can varie from 7.8 to 24.1 amps

On my side, i'm only using a 15 Amp breaker and so far, working for me. The vacuum have almost 0 load and i doesn't cut hard wood.

But, best thing to do should be 2, 15 amp breakers. I'm not saying to use 240v here. I means one Hot and one neutral by output. It's 120v by output with 2 different breaker.

It's like a kitchen outlet. We can plug a toaster and a kettle in same time because each outlet have different breaker.

Now, if you have 230V/50Hz the current is a half. I dont thing that will be a problem for you.

Step 11: The End

I hope you have enjoys this project. At first i tough that this project should be easy to do. But i under rated some parts. The 0 crossing wasn't easy to deal with. It's not a sqare 0-5v output but sort of pulses so i spend some time with my oscilloscope to match the timing.

Also the current sensing part was time consuming too. I tried with some op-amp, with some wire pass throw a coil etc. At the end i found this transformer cse187l. And surprise the output was very strong. No need to add an op amp anymore.

230v is supported but... in north america we dont have 230/50 HZ. So program detect frequency. I tested with a frequency generator. But i dont have tested the whole thing in real life. If some of you did the project just confirm me if all is ok under 230v 50HZ.

Step 12: Demonstration With Saw and Light

As you can see the saw is starting slowly. I'm using a light bulb instead real vacuum for the demo.


Step 13: How It's Work

-As soon you plug the softstart in an outlet, the uC check the time between 2 zero crossing points.

-It's the way the uC know the frequency of the line, 50 Hz or 60 Hz and in the meantime the voltage it is dealing with. 50 Hz = 220V and 60 Hz = 120V

-Knowing that, uC send the good starting voltage on softstart power outlet. This starting voltage is different for 120 or 220v.

-It's why you see the opto led very dim when the saw is off. This is normal.

-When you turn on the saw power switch a current is appearing in T4. Doing a voltage spike through D2 and stay at high level until the saw is turned off. Zener diode protect the uC if voltage is too high. C7 is a low pass filter and transform the ac spike in DC. uC detect the high level and trig an interrupt.

In other word, when you turn on the saw power switch, 5v is on C7 and detected by the uC.

-Triac is trigged from 2% to 100% (duty cycle) in around 3 seconds and stay at 100% until the DC from T4 goes from hi to low.

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    101 Comments

    0
    trevor.gti
    trevor.gti

    1 year ago on Step 1

    Have to tried replacing the CSE187L for a ACS712 which is a easier product But will need a differential amp

    0
    Yannick99
    Yannick99

    Reply 1 year ago

    Let me know

    0
    trevor.gti
    trevor.gti

    Reply 11 months ago

    Your explanation does not say how the circuit works. You just mention which section does what. Please explain. How do you get current at T4 is Triac is off.
    trevor.gti@gmail.com

    0
    Yannick99
    Yannick99

    Reply 10 months ago

    The triac isn't completely off. A starting voltage is present. This one trig a pulse in T4 and detected bu the mcu.

    0
    trevor.gti
    trevor.gti

    Reply 10 months ago

    So how does the the circuit sense when the tool is switched on ? or does this circuit only work when mains input is switched on ?

    0
    Yannick99
    Yannick99

    Reply 10 months ago

    The softstart is plug in the wall outlet. The switch saw is off. A few voltage is present on the softstart outlet. When you turn on the saw, some current if flowing in T4. This do a spike through D2 and trig the uC interrupt.

    I will add a step to explain how the circuit is working in more detail.

    0
    trevor.gti
    trevor.gti

    Reply 11 months ago

    You dont need a zero crossing if you use a MOC 3041 which has a built in Zero crossing So that circuit can be removed

    0
    Yannick99
    Yannick99

    Reply 10 months ago

    No you wrong. The mcu need to know exactly when to trig the triac. So we need to have a zero crossing detection circuit.

    0
    trevor.gti
    trevor.gti

    Reply 10 months ago

    If a voltage is applied at any time to the MOC it switches on when its zero volts hence a 3041 is better It has a zero crossing switch built in I use it all the time

    0
    Yannick99
    Yannick99

    Reply 10 months ago

    Hi Trevor, I know what you mean. And you right about this (3041 have 0 crossing) But i'm sending a wave form from 2% to 100% duty cycle in 3 seconds. And I didn't want to have a "hi" when the opto wasn't to 0. Even I know the opto (3041) will wait until it reach 0 before the start. I have more control like that and it's something else.

    I needed this 0 crossing detection to know the speed of the line. 50 or 60 Hz. Again you will tell me that if i was using 3041 no need to know this. In fact, it's handy to know this because this tell us the voltage I'm dealing with. The starting voltage is different with 120v or 220v.

    So, one schematic, one code for everybody. And it's why i decide to go with a 0 crossing detection circuit.

    Hope this help to understand.

    Yannick

    0
    Rogerino
    Rogerino

    10 months ago

    Bonjour Yannick
    J'espère que tout va bien avec vous, puis-je avoir de l'aide avec le soft start? Dernièrement, je dois recommencer plusieurs fois jusqu'à ce qu'il commence à fonctionner. Je ne sais pas ce qui ne va pas, le moteur démarre directement sans problème lorsqu'il est connecté directement à 110v, mais via le softsart, je dois allumer et éteindre plusieurs fois pour le faire fonctionner.
    Cordialement
    P.S. Si vous connaissez quelqu'un qui a besoin d'un PCB de votre circuit ou de celui a DenisL57, j'ai quelque un de chaque a doner, envoyez-moi un mot,
    goldring101 à courrier chaud.com
    R.G.

    0
    Yannick99
    Yannick99

    Reply 10 months ago

    Soit, le voltage de départ ne doit pas être assez haut pour votre scie. Cela fait que le peak de démarrage est marginal et souvent trop bas pour être détecté.

    Ou soit que le circuit du tranfo T6 n'est pas assez performant.

    Ce que vous pouvez faire. Remplacer r6 par une 1k et/ou d2 avec une schoky diode. Vous gagnerez quelque milivolt ce qui peut être suffisant.

    Sinon on modifie un peu le programme pour avoir une tension de départ plus grande. Je peux le faire ou vous donner le code source.

    Yannick

    0
    Rogerino
    Rogerino

    Reply 10 months ago

    Bonjour Yannick
    Merci pour une reponse rapide, J'ai le code source que vous avez mit sur le net, comme je ne comprend rien en assembly j'ai pas trouver la ligne pour modifier. Ci vous pouvez me le faire ca sera bien apprécié.
    Je vais essayer de remplacer R6 & D2 et si ca ne fonctione pasje vais reprogramer le atmega 328 avec le code que vous aller menvoyer.
    Cordialment
    Roger

    0
    Yannick99
    Yannick99

    Reply 10 months ago

    D'accord laisse moi savoir par email c'est plus rapide. agaguk_99 a hotmail point com.

    0
    Rogerino
    Rogerino

    Reply 10 months ago

    Merci Yannick
    J'ai envoyer la reponse sur hotmail
    Roger

    0
    pelake2005
    pelake2005

    Question 1 year ago

    Hi Yannick99
    Your design is best, I use 230v AC, it's relay difficult to find T3 FS12-090-C2 & T4 CSE187L in the UK , specially t3 , is it possible to use another components instead to do same things please.
    Thank you

    0
    trevor.gti
    trevor.gti

    Answer 1 year ago

    Any simple basic transformer can be used T3 It can be quite a lot smaller as its only used for 5v supply to controller

    0
    Yannick99
    Yannick99

    Answer 1 year ago

    Hi, sorry for the delay. For t3 you can use any 230v/12v. Just maybe check for the pad layout if hole are in same place.
    T4 is different. It's a current sense. Probably some other will do the job. But i can't recommend any. The spike on uC side must be high enough to fire the start.
    Check on ebay i saw some shipped worldwide.

    0
    trevor.gti
    trevor.gti

    1 year ago

    Nice circuit can you not use a smaller simpler cheaper controller ?

    0
    dobernik
    dobernik

    1 year ago

    I'm using 230VAC and the circuit behaves this way:

    When there's no load on the outputs (and pins 1,3,4 not connected anywhere):
    - Zero crossing detector give correct pulses to pin4;
    - Led 1 blink with barely visible light, LED 2 is dark;

    When switch on the table saw is put to ON:
    - after 3-5 sec the motor try to start like geting short pulses (LED 1 blink the same way as mentioned above).
    - sometimes after pulsating the motor start to run softly (like expected), both LED became normal bright) and then with full power. The voltage on the C7 rises from 0 to about 4V. Pulses on pin 12 correctly get wider and wider as motor goes to full power.
    - on other cases motor just pulsates erraticaly and finally stops. Voltage on C7 rises up to about 3V and then drops.
    SInce I cannot see the code I do not know how uC detect when the table saw is powered on. I assume that there should be some short trigering pulses on pin 12 to enable motor to start (means the T1 is totally opened). After switching the motor ON pulses from T4 should start the proces of soft start. Am I right? On osciloscope I can only see some very small spikes on pin12 which cannot triger the triac. Can you please let me know how the circuit should start?

    BR