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<div class="moz-cite-prefix">That idea should work fine.<br>
<br>
The clever bit is to figure out how to source the large drive
currents required to overcome the input capacitance of the output
FETs, allowing the FETs to switch quickly (and not generate heat).<br>
<br>
Part 2, is to manage all of the circulating currents so that
everything goes where it is supposed to.<br>
<br>
Part 3 is to specify capacitors which can manage 2 above without
overheating, or exploding :)<br>
<br>
In all seriousness, have a look around before you climb in :
<a class="moz-txt-link-freetext" href="http://www.robotpower.com/products/osmc_info.html">http://www.robotpower.com/products/osmc_info.html</a> appears to have
gone through quite a few revisions, and may be stable now.<br>
<br>
The <span style="color: rgb(0, 0, 0); font-family: Verdana,
Arial; font-size: small; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; background-color: rgb(255, 255,
255); text-decoration-style: initial; text-decoration-color:
initial; display: inline !important; float: none;">HIP4081A is a
popular H bridge driver, has hi and low side translation, can
deliver a couple of amps gate current, and has an overlap
generator so that top and bottoms FETs do not switch on at the
same time.<br>
<br>
A 'typical' output FET may have 5000pF gate capacitance, and for
a 10V change in 100ns will need around 500mA peak. Allowing gate
voltage to change slowly can generate lots of heat (since the
FETs will spend time in their linear region, which is V
undesirable).<br>
<br>
Anyway, just my 2c<br>
<br>
</span>Regards, Mark<br>
<br>
On 24/02/2018 5:39 PM, Andrew Errington wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAGZkoWQbQPTVR2FkP8rDoje+Js+sL=LCfSJ+bavKBP6f+7CiuA@mail.gmail.com">
<div dir="auto">Thanks for your suggestions everyone. I might get
lucky if I can get an ESC without braking (or can be configured
to turn that off), otherwise a micro to read servo control
pulses and drive an H-bridge.
<div dir="auto"><br>
</div>
<div dir="auto">Best wishes,</div>
<div dir="auto"><br>
</div>
<div dir="auto">Andrew</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Feb 24, 2018 11:31 AM, "Robin Gilks"
<<a href="mailto:robin@gilks.org" moz-do-not-send="true">robin@gilks.org</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
> Hi Synco,<br>
><br>
> Thanks for replying. I'm sorry, I should have mentioned
the motor type.<br>
> Simple brushed dc motors.<br>
><br>
> I could build something, but I'm looking for an
off-the-shelf module.<br>
> Popular and cheap fits the bill.<br>
><br>
> Thanks,<br>
><br>
> Andrew<br>
><br>
<br>
I used these to drive the 24v wheelchair motors on my walnut
washer.<br>
<br>
<a
href="https://www.aliexpress.com/item/Double-BTS7960B-DC-43A-Stepper-Motor-Driver-H-Bridge-PWM-For-Arduino-smart-Car/32647125360.html"
rel="noreferrer" target="_blank" moz-do-not-send="true">https://www.aliexpress.com/<wbr>item/Double-BTS7960B-DC-43A-<wbr>Stepper-Motor-Driver-H-Bridge-<wbr>PWM-For-Arduino-smart-Car/<wbr>32647125360.html</a><br>
<br>
They don't even get warm @ 5A<br>
<br>
No idea if there is anything available here for less that 5
times as much!<br>
<br>
<br>
--<br>
Robin Gilks<br>
<br>
<br>
<br>
<br>
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