Motor Speed Control

[Marcus]

I'm just wondering of anyone has any alternative for using an RC Car speed
controller ? I'm building a robot and need speed contollers and the PWM
input and analog voltage output of the premade speed controllers is ideal,
however, the cost is not. From towerhobbies.com the price is $80+ which is
a expensive.

Any ideas how to vary voltage (high current too) via PWM would be
appreciated.

Thanks,

Marcus

 

[Paul Burridge]

On Fri, 12 Nov 2004 19:26:17 -0500, "Marcus"
<mkennedy@lakeheadu.ca.Removethis> wrote:

"Marcus" <mkennedy@lakeheadu.ca.Removethis> wrote in message
news:jXbld.10370$14.5496@read1.cgocable.net...
I'm just wondering of anyone has any alternative for using an RC Car speed
controller ? I'm building a robot and need speed contollers and the PWM
input and analog voltage output of the premade speed controllers is ideal,
however, the cost is not. From towerhobbies.com the price is $80+ which
is a expensive.

Er, no, it's *dirt* cheap, actually. If you can find ready-built
controllers that will do the job needed at that stinking, low price,
you'd be a fool to try to roll your own for anything other than fun.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Paul Burridge]

On Sat, 13 Nov 2004 19:58:56 GMT, Rich Grise <rich@example.net> wrote:

One thing to be aware of - when you're using RC servos, they're
designed such that if they lose the signal, they just sit in
the position they're at - they don't "home" or anything - I
guess the reasoning is, if you lose the RF signal, the airplane
just continues in whatever turn or dive it's in, so the damage
will be predictable. ;-)

In Robot Wars in the UK., we're compelled to use FS1s or equivalent to
counter this problem.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Paul Burridge]

On Sat, 13 Nov 2004 19:58:56 GMT, Rich Grise <rich@example.net> wrote:

One thing to be aware of - when you're using RC servos, they're
designed such that if they lose the signal, they just sit in
the position they're at - they don't "home" or anything - I
guess the reasoning is, if you lose the RF signal, the airplane
just continues in whatever turn or dive it's in, so the damage
will be predictable. ;-)

In Robot Wars in the UK., we're compelled under the rules to use FS1s
or equivalent to counter this problem. They return the servos to a
predetermined, safe default setting in the event of signal
loss/interference. They only cost about 25 bux a piece in your dough.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Paul Burridge]

On Sat, 13 Nov 2004 21:33:56 GMT, Carl D. Smith
<cdsmith69NOSPAM@earthlink.net> wrote:

Wow. This one claims maximum continuous current of 232 amps
and maximum peak current of 800 amps, for $65.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LL4926&P=1

Do they supply the fully-electronic/solid-state ones and if so, for
how much?

--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Fritz Schlunder]

"Carl D. Smith" <cdsmith69NOSPAM@earthlink.net> wrote in message
news:rdvcp0l9g25efml4ejh5ad5sosl02ebh8l@4ax.com...

Wow. This one claims maximum continuous current of 232 amps
and maximum peak current of 800 amps, for $65.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LL4926&P=1

Hmmm... Surely they must have gotten a decimal place wrong or something on
that? 232^2*0.0035 = 188 Watts. I think that small a package would have a
very hard time handling that continuously. Additionally I don't think 14
AWG wire would much like 232 Amps flowing through it for very long. Surely
23.2A continuous and 80A peak would be much more likely for a 0.0035 Ohm on
resistance and 14 AWG wires...