Anybody have a good L298 driver board ???

[epineh]

I am in the process of doing a dirt cheap small servo board, I need a H-bridge to take PWM signals from EMC directly and run the servo(s).

Does anybody have a simple circuit, board layout or anything that will give me a head start, I have some L298's and was going to use these, but can make something to suit Mosfet's if that is easier (or better).

The servo's for this app are low power, a couple of amps and 24-30Volts should be fine.

Circuit design is really not my strong point so I am happy to bludge on that part. I can produce my own boards, from schematic if needed, if that helps.

Cheers.

Russell.

[mr jones]

Russell.......

Someone correct me if i am wrong, but wont the L297 chip I am using suit this mans purpose for driving the L298?

Russel, If I am not mistaken........the PCB schematic you want can be found on the L298 PDF Datasheet......Its the circuit I am using to drive my Unipolar steppers, but it should work just as well for your purposes I THINK. If I am mistaken may i be struck down by lightening and given 1000 lashes with a wet noodle.

The L297-L298 combo circuit on the L298 PDF Datasheet seems downright simple at first glance.......Yet is downgraded in my opinion to merely "fairly simple" once you start to assemble it because the parts layout on the board is mildly confusing (and shows an extra capacitor where i can find no call or need for one) but all in all seems to come highly recommnded and the parts fly together fairly quickly.

But someone correct me if I am mistaken.....For I am no expert here.

Good Luck!

[Madclicker]

The L297 is a stepper translator chip. He wants to build a servo drive.

[samco]

http://emergent.unpy.net/projects/01148303608

sam

[skullworks]

The L297 is a full/half step driver chip which can output the coil phase signals to the L298n H-bridge which actually switches the current thru the windings thru a diode grid.

Key phrase for L297 is "Stepper" motor.

Key phrase for OP was SERVO

To see a simple direct use of the dual H-bridge L298n check out the Solarbotics card .

Here is the Schematic http://downloads.solarbotics.net/PDF..._schematic.pdf

In the L298n data sheet it has a schematic to parallel the dual channals to get 4A capacity. Using this same method I have seen a working board that ganged up 3 L298n's to run an 8amp motor but keep individual driver chip temp lower.

L298's do run hot under load so use a generous heat sink!

I have been toying with a 5 chip dual axis servo drive circuit for use with EMC2 - it is just a ganged H-bridge. (this has no current limiting so running a motor into a hardstop without limit switches could blow the chips) This could be run off a paraport for a 2 axis lathe. I plan on driving 3 axis using a pluto-P.

Once the circuit has proven itsself it will be posted on the EMC2 wiki.

The Solarbotics unit can be modified by switching out the 8 1amp diode with 4 6amp diodes and changing out the 5v reg to a noraml 7805, or leaving the 5v reg circuit out completely and suppling the 5vdc from an off board source. Also the second pair of LED's would be omitted. This would allow using the full potential of the L298n.

[epineh]

Originally Posted by mr jones If I am mistaken may i be struck down by lightening and given 1000 lashes with a wet noodle.

Lol, now I gotta find a noodle and some water

Sam, can I use two of those boards to make a 4 axis system, using extra parallel port's, and setting it up properly with HAL ?

Skullworks, thanks for the tips and schematics, now I gotta do a little research and work out what I am going to make...

Thanks all!

Russell.

[epineh]

I have decided to try Jeff's board layout that Sam listed, main reason is that I can get a test platform up and running in a very short time, I may chop the parallel port connector out later to make a H-bridge only board, with headers to a breakout board.

But for now I have done a board, actually did 2 for good luck, just have to drill and populate...

Cheers.

Russell.