HmmmâŚerror in the diagram?
It seems that the small caps (0.1uF) are depicted with the symbol for electrolytic caps, but they sure look like ceramic caps on the fotos? Correct me if Iâm wrong?..
Theyâre probably Tantalum
Theyâre probably Tantalum caps, judging from the appearance, value and polarisation.
Damnit âŚ
Damnit I think youâre right. The 3rd kind I allways forget. Another noob mistake on my part. Man it isnât easy learning electronics. A lot of incomplete or wrong information around. Guess Iâll have to find a better symbol list.
Besides these things look VERY similar to the ceramic ones
No plus sign = ceramics
No plus sign = ceramics probably. Note the plus on the actual electrolytic. Sometimes folks use whatever symbol is handy (in graphics) for the device they have.
It does appear they have a place for caps on the LadyAda Motorshield between ground and motor outputs, but they appear to not be populated. Iâd probably omit those 4 too.
Iâll keep that in mind
And the problem with the symbols is that the description I posted above (as well as many others) says the symbol with a plus sign is an ELECTROLYTIC cap. Thatâs apparently incorrect. It simply means a POLARIZED cap? Furthermore the ones with no plus could mean both a tantalum or ceramic one, allthough tantalum caps are polarized too? Oh well Iâll get used to it sooner or laterâŚ
Still wondering
HOW can you tell itâs a tantalum cap judging from the appearance, value and polarisation?
According to the diagram theyâre NOT polarized (tantalums are). The value could be both ceramic and tantalum (or am I wrong?). And the appearences of the two types are extremely similarâŚ
You can also get
You can also get non-polarised electrolytics, which naturally have no (+) sign at all =D
Damnit!!
Youâre just saying that to confuse me
There are other
There are other non-polarised types too, such as polyester, aluminium foil, green capsâŚ
At the end of the day only a few things really matter for most uses: capacitance, maximum voltage and polarity. Sometimes youâll need to know the equivalent series resistance, leakage rate, or other details but normally you donât worry about them.
To guibot!
Now I gotta know for sure: Are the o.1uF caps tantalum OR ceramic?
DâOH!
"There are other non-polarised types too, such as polyester, aluminium foil, green capsâŚ"
L293D for noobs
Just found this tutorial and thought Iâd share it. It explains how the L293D works in details so even noobs (like me) canât possibly misunderstand it.
Plus the accent is great
hi
Hi. LMR world⌠. i dont have any PICAXE or arduino or any other development board⌠Is there any alternative way of checking it out??Â
First - thank you for this
First - thank you for this tutirial. Now the question. On the first foto you have 2 big caps before and after the voltage regulator. But then you have 2 smaller but not 0.1uF caps on the Vss and enable pin of the L293. On the schematic later you only have 2 âbigâ caps, but on the first foto 4! Why is that, and do I need additional âbigâ 100uF caps on the L293. Thank you
Caps
The two caps on the first foto are, as you can see here very advisable.
The other caps on the drawing are meant to supress electric noise and voltage spikes⌠you can try all the circuit without the caps and it will work, but remember it is always a good practive to use them. I am no EE though and I apologize for not being able to explain this in greater details.
Problems when using it with a Tamiya Twin Motor Gearbox
Hey, Guibot!
Obrigado pelo bom tutorial!
I have been experimenting with this same IC and I am having unidentified problems. Mainly when using it in conjunction with the Tamiya Gearbox. The problem is that those motors use only 3VDC.This is below the minimum specified voltage for the IC VCC. I was wondering if there are any limitations to VCC2 or pin 8. Can I simply apply 3VDC to pin 8 and get them out of either output pin (if enable and control pins are high)?
Or do I need to use 5VDC for everything (including pin 8) and drop them down to 3 VDC after the output pins with some diodes?
Thanks for your help,
AndrĂŠs
The L293D drops about 1.5V
The L293D drops about 1.5V from the supply you give it to what the motors actually see. So if you supply 5V the motors will actually see about 3.5V, which should be fine.
Thanks, Ignoblegnome. I will
Thanks, Ignoblegnome. I will do that then.
Cheers!
AndrĂŠs
Same problem
Hi Andres,
I kinda have the same problem. I bought a Tamiya double gear box (double gear) and i am using a Arduino Mega ADK board. I understand that the motors are rated @3VDC. Did u get them to run now? Also I am using a L293DNE motor driver. My circuits are according to this example and the code too. But my motors/motor doesnât respond. Any suggestions?
Â
Gokul
Try thisâŚ
Hey Gokul,
Yep. I got them running. If yours don´t spin AT ALL, make sure the following is happening:
- Pin 16 is getting between 4.5 and 36VDC.
- Either or both pins 2 and 15 or 6 and 11 get a logic high.
- That the enable pins (1 and 9) are high at the same time of the ones in the previous point.
- That the GND is common between the L293D power supply and the mcu power supply.
- Pin 8 gets at least 4.5VDC.
Here is what I´ve learnt: pin 8 (motor V+) will not accept anything below it´s minimum rating: 4.5 VDC. In my own research, the IC will drop between 0.5 and 0.8 VDC. That means you will be supplying between 4 and 3.7 VDC to the motors. In my case, that was still too hot for my motors. I solved it doing something that should not have solved it. I hooked a bicolour LED (common cathode) in parallel to the IC´s motor output. So, if the motor spins CW, the green half of the LED lights up. If it spins CCW, I get a red.
Hope this helps.
AndrĂŠs