modulation speed control on trolling motors?

[MBS]

To my knowledge, trolling motors now made with variable speed control
have modulation control circuits built in to improve efficiency (as
opposed to older resistive controls). However, these are not available
on lower thrust motors. In this link is a company that makes on of
these and claims to improve battery longevity by 6 times. Being this
is rather expensive, my question is whether anyone can point me to
plans or other references where I could design one of these myself?

http://www.lightperformanceworks.com/Kit_Specs/kit_specs.html

Thanks!
Bailey--

 

[default]

To my knowledge, trolling motors now made with variable speed control
have modulation control circuits built in to improve efficiency (as
opposed to older resistive controls). However, these are not available
on lower thrust motors. In this link is a company that makes on of
these and claims to improve battery longevity by 6 times. Being this
is rather expensive, my question is whether anyone can point me to
plans or other references where I could design one of these myself?

http://www.lightperformanceworks.com/Kit_Specs/kit_specs.html

Thanks!
Bailey--

Search on these words> pwm speed control schematic circuit

http://www.solorb.com/elect/solarcirc/pwm1/ Has one

http://www.commlinx.com.au/control.htm another link

 

[MBS]

Thanks. I meant to also ask if someone could recommend a company that
sells these for a resonable price. If not, then maybe partial
components that can be assembled.

 

[default]

Thanks. I meant to also ask if someone could recommend a company that
sells these for a resonable price. If not, then maybe partial
components that can be assembled.

You're gonna take the fun out of it.

Jameco has a DC lamp dimmer kit, which does what you want but not with
the current a trolling motor might draw.

I figure you might need 20 amps or more and I know of no off the shelf
device or kit that is reasonably priced. There are DC motor
controllers for hobby RC cars but 5 amps is the limit there and they
cost a lot.

It's a wide open market if you want a business. Probably a lot of
golf carts still running around with resistance controllers as well.

I'd use a 555 timer wired as a pwm astable multivibrator driving a
power mosfet or darlington transistor. That would be ~$20 in parts.
A couple of 2N3771's in parallel for 30 amps ($4) or a 27 amp mosfet
($.81 if that isn't a typo in the Jameco catalog)

 

[Peter Kiproff]

You're gonna take the fun out of it.

Jameco has a DC lamp dimmer kit, which does what you want but not with
the current a trolling motor might draw.

I figure you might need 20 amps or more and I know of no off the shelf
device or kit that is reasonably priced. There are DC motor
controllers for hobby RC cars but 5 amps is the limit there and they
cost a lot.

It's a wide open market if you want a business. Probably a lot of
golf carts still running around with resistance controllers as well.

I'd use a 555 timer wired as a pwm astable multivibrator driving a
power mosfet or darlington transistor. That would be ~$20 in parts.
A couple of 2N3771's in parallel for 30 amps ($4) or a 27 amp mosfet
($.81 if that isn't a typo in the Jameco catalog)

That's what I did for a friends boss that blew up his controller

a 555 with a TO-247 fet, I also put a fast diode in a TO-220 pkg
worked fine but @ 16khz was too noisey so I turned it up to 25 khz
then he was happy.

Peter

 

[pkh]

If you don't want to start from scratch, you could get one of these
lower current kits and just add more drive FETs (and/or FETs with higher
current ratings). You may load down the circuit driving the output FETs
if you add too many, so you'll have to experiment...

Regards,

Paul

 

[N. Thornton]

To my knowledge, trolling motors now made with variable speed control
have modulation control circuits built in to improve efficiency (as
opposed to older resistive controls). However, these are not available
on lower thrust motors. In this link is a company that makes on of
these and claims to improve battery longevity by 6 times. Being this
is rather expensive, my question is whether anyone can point me to
plans or other references where I could design one of these myself?

http://www.lightperformanceworks.com/Kit_Specs/kit_specs.html

Thanks!
Bailey--

Hi. Improving battery longevity by 6x sounds very optimistic. PWM
control is quite a bit more efficient, but 6x? Hardly. If you happen
to run your motor at the most inefficient setting possible, ie at very
slow speed using an R controller, then you could get 6x. But if you
use it at full whack, there is no efficiency gain there at all.

I'd use opamps to produce a variable m/s square wave, which is what
you need.


Regards, NT

 

[Roy J. Tellason]

[email protected] (MBS) wrote in message


Hi. Improving battery longevity by 6x sounds very optimistic. PWM
control is quite a bit more efficient, but 6x? Hardly. If you happen
to run your motor at the most inefficient setting possible, ie at very
slow speed using an R controller, then you could get 6x. But if you
use it at full whack, there is no efficiency gain there at all.

I'd use opamps to produce a variable m/s square wave, which is what
you need.


Regards, NT

Why throw an op amp at something like this? Take a CMOS schmitt trigger part,
use one gate as an astable oscillator and vary the duty cycle, all that
takes is one cap, one pot, and a couple of diodes. Any unused gates in the
package can buffer the output, and handling of power could be done with a
power darlington. That's a total of 4 passive components and 2 active ones,
maybe a bit more if you need a protection diode across your power part,
noise filtering, etc.

Why complicate things unnecessarily?