Hello my RC car has a 7.2 Volt 2200 mAh battery. I used an dual L298N H-bridge to control it but nothing happened.Only was working on 255 PWM and very very slow.
I connect directly motor to battery and with multimeter saw that on air motor need 1.8 A
When i block intantly the motor, it needed 4.8 A.
So the L298 gives max 2 A and i cant use it.
Any suggestion to make an H-bridge that can work with 5-6A fine ; H-bridge with power Mosfet is the only solution;
I think a part like this
driving 4-N-Channel MOSFETS
would probably work well for you.
Yes but the driver says "Voltage - Supply 8.5 V ~ 15 V "
I need supply it with the 7.2 Volt from RC car battery.
If someone can post a schematic i will be pleased
Can you follow the schematic in the datasheet?
I mean to make it with some Mosfets and transistors, like IRF9540 and IRF540
if someone can help 
I made that H-bridge but no results:
o Replace the 10k resistors on the top FETs with 680 ohm resistors
o lose the 100 ohm resistors
o change the 22k base resistors to 4k7
o run it at 10V to 15V (so the p-channel MOSFETs have the correct gate drive)
o replace the IRF540's with logic-level n-channel MOSFETs
o add 150 ohm resistors inline with the n-channel MOSFET gates.
o change the p-chan MOSFETs to one's with less on-resistance, 0.03 ohms or less.
Then that circuit will work and be able to PWM at reasonable speeds.
You'll need to drive it with some dead-time between high-side and low-side
conducting, perhaps only a few us.
I must supply it with 7.2 volt , cause its the only battery i havw with those mAh ..
Any suggest for what n & p Mosfets to use ;
You'll then need logic-level MOSFETs top and bottom - but make sure the gate-source
max voltage for the p-channel FETs is well above 7.2V (well, below -7.2V to be precise).
I made some changes but i dont know with what mosfets to change the IRF9540 and where to place the 150 ?? you said
Pololu has ready made motor drivers, at reasonable cost, that will do what you want: Pololu - Brushed DC Motor Drivers
I know ,but a want to make that bridge and no buy it
For instance look at the suggested circuit at the bottom of page 1 in this datasheet:
That's a half-H-bridge, so double it up to make an H-bridge. There are many other
similar high-side-low-side MOSFET driver chips to choose from. You do need 10 or
12V for them (a small boost conveter from 7.2V would provide that). The MOSFETs
are non-logic-level n-channel, giving a wide choice. Such H-bridges can run at almost
any voltage from <1V to 600V (depending on devices), since the MOSFET supply
is separate from the driver's 12V.
This idea my friend wont work ;
Legolas69:
I know ,but a want to make that bridge and no buy it
The below might be good reading id you are considering a DIY h-bridge. Note that MOSFETS need to be logic level to be directly driven from the arduino. Ebay has inexpensive h-bridge motor drivers for the arduino.
They sell on ebay for less than $2.
Making your own is kinda like making your own paper.
You can, but why?
John
Because i want to learn and dont take something that is ready
I made an H-bridge with 12 Volt suply and worked perfect, the problem is that i must make one for 7.2 Volt cause i change the battery i have now (its from the RC car )
Somewhere i read that i must not use IRF but IRF mosfet .
Basicly thats the best schematic i found and most logic to me:
http://cdn.instructables.com/FDQ/NF1D/GWF60U03/FDQNF1DGWF60U03.MEDIUM.gif
Can anyone tell me what i must make/change to make it work on 7.2 V supply for a motor needing 4.8 A ;
Both of the below h-bridges have specs that say the lower limit voltage is around 6v. I doubt you will be successful in making an h-bridge any cheaper.
I know, its just about not cheap or no. Its about making something alone
Last time a made that bridge and was working perfect on 12 V. Its H-bridge for 8051 microcontroler but was working for my Mega too. The 2 LED for up Mosfets are used to driver them to "cut" (5+2+2 V)
Now i need replace those led with NPN transisor. Any idea ;