>
> What is the frequency of your PWM? The 754410 is happiest at 2KHz or
> lower. At 20KHz I've detonated these chips!
>
> DLC
>
> ooPIC Tech Support
>
>
I got the Sabertooth, and it operates in a decidedly undesirable fashion
where the range of speeds is 0-127 (or was it 255) where 0 is full reverse,
and the other end (whatever it is) is full forward. Everything else is
somewhere in the middle. Off is therefore "something in the middle", but the
exact off point is slightly different for each wheel, and power draw might
be pretty high even at that point. Therefore, I started putting together a
circuit where the power would be switched off except when the wheels should
be turning.
However, I decided to try something different with the original H-Bridge,
and this message was the key point. The original problem was the speed. Once
I pre-scaled the PWM down to the lowest frequency possible, the motors began
operating the way I wanted them to originally. I still need some of the
circuit mentioned above, but for totally different reasons.
The thing that got me to re-test the original H-Bridge was finding a
different spec sheet for it that suggested that it wouldn't actually melt
with the power requirements I have. The chip gets a bit warm, though. There
is a heat sink that sandwhiches the chip between two pieces of metal with
fins on the top side. The heat sink has only a tenuous connection with the
chip, so I was thinking of adding some thermal contact grease to improve the
contact between the heat sink and the chip.
My question is this: It appears that the chip will work as long as it
doesn't burn up. How can I improve the cooling of the chip using passive
means (no fans or water cooled systems)?
--
View this message in context: http://www.nabble.com/H-Bridge-issue...maybe.-tp13928519p15793085.html
Sent from the OOPic mailing list archive at Nabble.com.
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