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Author Topic: L293D alternative  (Read 1178 times)
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Hey, everyone, I tried this circuit:

http://farm5.staticflickr.com/4092/5030023537_054846f468_z.jpg

with a component that I believe is very similar to the L293D used in the picture. Further more I got this component from an old rc car which really makes me believe it is used to control simple dc motors spinning direction. Here it is:

http://sdz-upload.s3.amazonaws.com/prod/upload/data1.JPG

But the circuit doesn't work. Does anyone know where I can find the datasheet for my component: R67370S 0215, by New Bright Toys? I guess the pin configuration is different...
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if you just have one or few pieces, might not be worth to trouble. but if you reverse engineer the diagram might help a lot. or drop a line to http://www.newbright.com/
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Did the RC car that chip came from have any transistors?

Did the RC car that the chip came from have a separate radio receiver?

If you answered Yes to the first and No to the second then what you probably have is an RC receiver and not a dual H-bridge.

See this page for a similar NewBright toy:
http://www.et.byu.edu/~bmazzeo/LTR/tech.phtml
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Without any documentation, what lead you to believe it was the same as another component?
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Without any documentation, what lead you to believe it was the same as another component?

X-ray, ... if worth to trouble, reverse engineer could ... since New Bright has no IC fabrication capacity.
« Last Edit: June 28, 2013, 12:29:57 am by sonnyyu » Logged

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2 of you guys talked about reverse engineering. What do you mean to "reverse engineer the diagram might help a lot" ?

Attached is a picture of the board I got the component from. You can see the rectangle on the board is where the part originally was located.


* daaaaa.jpg (496 KB, 800x719 - viewed 44 times.)
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You'll need to follow the traces on the reverse side of the board and need to know which of the connectors
on the board went to which part of the RC car before being able to determine the role that chip played.
It's quite likely its a microcontroller pre-programmed specific to that toy - there is a lot of discrete transistor
circuitry on that board which may or may not be RF receiver circuitry (can't see any obvious quartz crystal).

"Reverse engineer" = "detective work".

Absolutely no a-priori reason to suspect that that chip is a motor driver (there are several power devices on
heatsinks already taken from the board that are much more obvious candidates for this role)
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"there are several power devices on heatsinks already taken from the board that are much more obvious candidates for this role"

Such as?
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The chip is going to be a microcontroller to pick up radio, and determine direction based on the RF input..

I've got my eye on J7 in the corner for having output to the motor.. It looks like it could be driving PWM.
« Last Edit: June 28, 2013, 06:33:06 am by tocpcs » Logged

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So no chance to use it as a L293D alternative?
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very minimum to none.
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So no chance to use it as a L293D alternative?

What you have there is likely the RX2 half of the TX2/RX2 radio-control chipset, a chipset that is commonly used (though nowadays the SMT variant is more often found) in low-cost radio-control toys from manufacturers like New Bright. The receiver chip decodes a modulated signal (from an RF receiver on the vehicle's PCB) to then send on to control discrete component (generally) h-bridges that control the motors for steering and acceleration.

It is not an h-bridge IC itself (and likely you have damaged it attempting to use it as such).

If you want to know more about this chipset (and where to find datasheets), go to this thread:

http://forum.arduino.cc/index.php/topic,86883.0.html

Note that there are a ton of different datasheets for this chipset out there; I have recently found other members of this family (TX5/RX5 and TX7/RX7) - but they are all very similar, with the TX2/RX2 set seemingly the most popular/used by manufacturers in China (where most of these toys originate from).
« Last Edit: June 28, 2013, 11:13:15 am by cr0sh » Logged

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"there are several power devices on heatsinks already taken from the board that are much more obvious candidates for this role"

Such as?

Top left, two TO220 packages with an L-shaped heatsink tab (well they are silk-screened outlines for them),
also two packages on bottom left look like power transistors perhaps.   The linear package bottom right could
be something interesting too.
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Top left, two TO220 packages with an L-shaped heatsink tab (well they are silk-screened outlines for them),
also two packages on bottom left look like power transistors perhaps.   The linear package bottom right could
be something interesting too.

I'm willing to bet that those TO-220 devices are for a "bang-bang" electromagnetic steering mechanism (shown in a few of the different TX2/RX2 datasheets), and that the SIP device is an actual h-bridge (albeit low-power) motor driver of some sort (something like a BA7886).

mooop, if you go to the last page of that link I provided, there should be a link to a more recent forum thread where somebody managed to implement a means of generating the input control signal the RX2 chip expects from the receiver circuit (which is actually generated by the TX2 in the transmitter). You could just solder the chip back in place (remember to orient it properly when you do!) - then drive that input using some of the sample code given in that thread. That way you wouldn't need to go to the trouble of implementing a separate board from parts (unless that is your goal or you want to learn how to do it - no problems with that).
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