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Topic: Can L293D really be put in parallel? (Read 6435 times) previous topic - next topic

electricviolin

Ok I will try it out tomorrow and let you know how it goes
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

#16
Jul 28, 2015, 08:05 pm Last Edit: Jul 28, 2015, 08:23 pm by raschemmel
Each  section has an Enable, an "A" and a "Y" pin.
make sure that each pair of like pins are jumpered.

Section-1-En to Section-4-En
Section-1-A to Section-4-A
Section-1-Y to Section-4-Y


Section-2-En to Section-3-En
Section-2-A to Section-3-A
Section-2-Y to Section-3-Y
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MAS3

The problem is that you need to understand how the component works, at least for a bit.
This is why i have a large aversion to sites like instructables.
Over there they tell you "Do this and that, to create the world domination device", but they don't tell you what's going on inside that device.
If you roughly understand the component, you can find mistakes in explanations yourself.
And i'm certainly not stating that anyone actually has made such mistake.

Make distinction between words input, output and pin number.
I can see where you saw what you mentioned, and what went wrong if i take the above in consideration.

I can also understand that all the information, which isn't all synchronised might be somewhat overwhelming.
So help yourself and find a schematic of the internal function blocks of that chip you understand and or like the best, and print it as large as you can.
Keep that available when reading the tips given here and check the answers against that print.
That might help.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

raschemmel

Look at the  schematic of a discrete H-Bridge:
H-bridge

Essentially, what you are doing is taking a duplicate of the above H-bridge circuit, and
wiring it in parallel. When you connect one of your windings across pins 3 & 6, you are also connecting that winding across pins 14 & 11, because section-1 is in parallel with section-4 and section 2 is in parallel with section-3.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

I am slowly understanding how and why this works.

I want to check if this is the correct wiring:

8 go to 12V
12 go to 5V
1-9 go to 5V
2-15 go to logic 1
3-14 go to logic 2 (opposite of logic 1)
6-11 go to coil side 1
7-10 go to coil side 2
4-5-12-13 go to GND


"To invent, you need a good imagination and a pile of junk" -Thomas Edison

electricviolin

#20
Jul 28, 2015, 09:07 pm Last Edit: Jul 28, 2015, 09:08 pm by electricviolin
Wait thats wrong, it should be

8 go to 12V
12 go to 5V
1-9 go to 5V
2-15 go to logic 1
7-10 go to logic 2 (opposite of logic 1)
6-11 go to coil side 1
3-14 go to coil side 2
4-5-12-13 go to GND

So is this correct?
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

Repost it with the label "Pin-" in front of the pin numbers and the word "Input" or "Output" where appropriate, so it reads
Input  X => pin Y where "X" and "Y" represent whatever the number should be.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

#22
Jul 28, 2015, 09:22 pm Last Edit: Jul 28, 2015, 09:22 pm by electricviolin
(VCC2) Pin 8 go to 12V
(VCC1) Pin 16 go to 5V
(1,2EN - 2,3EN) Pin 1 - Pin 9 go to 5V
(IN 1 - IN 4) Pin 2 - Pin 15 go to logic 1
(IN 2 - IN 3) Pin 7 - Pin 10 go to logic 2 (opposite of logic 1)
(OUT 1 - OUT 4) Pin 3 - Pin 14 go to coil side 2
(OUT 2 - OUT 3) Pin 6 - Pin 11 go to coil side 1
(GND) Pin 4 - Pin 5 - Pin 12 - Pin 13 go to GND
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

#23
Jul 28, 2015, 09:32 pm Last Edit: Jul 28, 2015, 09:45 pm by raschemmel
Correct.

If you have any small heat sinks and thermal paste you can put a heatsink on top of each chip.

Test it with a 100 ohm resistor as a dummy load in place of each winding first.

Measure the voltage across the dummy load resistors for ON and OFF and post that info
for feedback. If it appears to be working correctly shut off the power and replace the resistors with the motor windings.

You can also substitute a LED in series with a 470 ohm resistor in parallel with a duplicate set with the polarity reversed for each winding so the GRN led turns on for one direction and the RED led for the other direction. Do that for each winding (two leds , opposite polarity with resistors for each winding. Don't parallel the resistors, parallel the led -resistor series combinations.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

I do have an old heat sink, but not thermal paste. I think it should be fine though because I am splitting the load among two ICs now (a single chip got very hot, but never blew).
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

electricviolin

I only have 1/4W resistors on hand - will that work for this test?
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

Yes
12V/0.020 A = 600 ohms (470 ok)

12/470= 0.025 A
P = I*V = 0.025 * (12V-2.2V) = 0.245 W (1/4 W)
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

I did the whole setup, and the motor turned. However, one side of one IC got very hot, while the others didn't. The motor was running, so both halves of all the ICs had to be doing something. I am not sure why only one half of one IC got hot.
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

Did you test the chips with resistor dummy loads and measure the voltage drop across them ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

I did, but it just fried the resistors... maybe they were 1/8 watt whoops...
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

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