This Forum is Dedicated For all The Object Oriented PIC Lovers .......... The concept behind OOPic is straight forward. Use preprogrammed multitasking Objects from a library of highly optimized Objects to do all the work of interacting with the hardware. Then write small scripts in Basic, C, or Java syntax styles to control the Objects. During operation, the Objects run continuously and simultaneously in the background while the scripts run in the foreground telling the objects what to do.

Monday, November 26, 2007

[oopic] Re: H-Bridge issue...maybe.

I see a great future in not using H-Bridges. Good ones are expensive
and usually there is some little gotcha just waiting to jump out. The
H-Bridge wants R/C signals and you have PWM or the H-Bridge can't
handle high frequencies or the minimum voltage is beyond the desired
battery ratings, things like that.

OTOH, you can easily reverse a motor with a DPDT relay controlled by
an OOPic output and a simple transistor or MOSFET. Then on the lead
between the relay and ground, use a logic level MOSFET (just one, not
four) and the job is finished. An IRL540N would be my choice for the
driver MOSFET and I might use an IRLD110 to drive the relay. I might
put 100 ohm resistors between the OOPic pins and the MOSFET gates.

The IRL540N can easily handle several amps and with adequate
heatsinking is good to 36A.

If braking is required, this approach needs a little more thought.
Basically, the DPDT relay is replaced with 2 SPDT relays and, of
course, 2 small MOSFETs and the original driver MOSFET.

In the end, the relay approach is cheaper and more robust.
Unfortunately, they don't seem to be commercially available. Too bad...

Richard



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