DC motor connected to an H-brige IC, does it need a transistor and a diode ?

hello guys, i need please to know if it is necessary to use a transistor and diode to make a connection between a dc-motor and a h-bridge IC ? nevertheless H-bridge is formed by transistors

Depends. Some H-bridges have diodes built in (L293D) while others do not (L293). http://www.ti.com/lit/ds/symlink/l293d.pdf Arduino can often drive H-bridge inputs directly - but sometimes not. Do you have more specifics?

Yes the H-bridge has all the transistors - BJTs or MOSFETs, and usually the diodes (MOSFET bridges always have built-in diodes since that's a property of power MOSFETs).

(Happen to be working on an H-bridge at the moment, rather a monster: )

then i must wait to see which h-bridge they will get me and then i will decide ? does additional transistor and diode have a negative effect on the circuit if the h-bridge IC has already a diode ?

What additional transistor? Perhaps I don't understand, but I'm assuming you mean an H-bridge with logic level inputs and direct output to motor terminals, which is the commonest sort on motor shields.

MarkT: (Happen to be working on an H-bridge at the moment, rather a monster:

Ok - I think we need some details on that contraption of yours!

Are those MOSFETs or IGBTs? Where'd you get them? How much were they?

...and just what are you building this insane thing for?

I was looking at IGBTs the other day, noticing how some were fairly expensive - but you could easily run an electric vehicle with 'em! Somewhere on the internet is a Prius "teardown" where they showed the IGBTs used - they were encapsulated in this weird super-clear gel or something - huge things. I think the guy was doing a plug-in conversion, and had decided to do the "tear down" to show the tech - pretty impressive.

So - is this h-bridge of yours for a vehicle or a robot? Or a robot-vehicle? Or something else?

i am building an RC car
so what i want to do is this : arduino connected to L293D and L293D connected to dc motor, my question is do i have to put a transistor (2N2222) and a diode between the L293D and motor ? or the L293D will do the whole work ?
check the attachment file please to see both setups

dc motor.jpg

motor with h-bridge IC.jpg

L293D does all the work. 5V from the board may not be sufficient. 500mA is available from USB. Up to 800mA from barrel jack, and less if the source is greater than 7.5V as the onboard 5V regulator heats up.

CrossRoads: L293D does all the work. 5V from the board may not be sufficient. 500mA is available from USB. Up to 800mA from barrel jack, and less if the source is greater than 7.5V as the onboard 5V regulator heats up.

one sec !! let me get it clear because now my head is really messed up !! i am giving arduino power from a 12V batteries set, i was told here that a 12V will be good with the transistor to make a motor run properly with full power so ? and about the usb you mean if the arduino is getting power from the usb ? and which regulator will heats up ?! i know that arduino will take care of a 12V source going into it and the transistor (2N2222) will amplifier current voltage so that the motor will take a 12V isn't that right ?

cr0sh:

MarkT:
(Happen to be working on an H-bridge at the moment, rather a monster:

Ok - I think we need some details on that contraption of yours!

Are those MOSFETs or IGBTs? Where’d you get them? How much were they?

…and just what are you building this insane thing for?

I was looking at IGBTs the other day, noticing how some were fairly expensive - but you could easily run an electric vehicle with 'em! Somewhere on the internet is a Prius “teardown” where they showed the IGBTs used - they were encapsulated in this weird super-clear gel or something - huge things. I think the guy was doing a plug-in conversion, and had decided to do the “tear down” to show the tech - pretty impressive.

So - is this h-bridge of yours for a vehicle or a robot? Or a robot-vehicle? Or something else?

Yup, robot vehicle probably - based on a 24V 2hp golf-buggy transaxle. MOSFETs since low voltage, IXFN200N10P
in SOT-277B package for about £15 each. FAN7392 drivers (3A gate drive) to go on a shield-style board atop the MOSFET slab.

I am hoping I don’t need the full 200A capability of the devices though, being rather conservative with the power handling.