Trolling Motor PWM design?

[gm280]

I am a retired Engineering Technician and worked for years reverse engineering older antiquated circuits and redesigning them to more useful and modern day components and better capabilities and more time between failures. However, I was just wondering if anybody on these boat comment boards has ever built a PWM trolling motor circuit? Yes I do have many schematics and could easily design one myself, but if somebody has already built one and did the R & D already and proofed it, I would like to get a copy or be pointed to the previous posting. So all you Electronic folks, put your thinking hats on and post your version with your proto-type results. Otherwise once I do the bread-boarding and circuit board design, I?ll post what I?ve designed and built with parts list and PC layout... Any takers? :happy:

 

[gm280]

Re: Trolling Motor PWM design?

Can we assume you mean Pulse Width Modulation?

Yes I guess I should have spelled that out. See I assume too much sometimes...

 

[fishrdan]

Re: Trolling Motor PWM design?

anybody on these boat comment boards has ever built a PWM trolling motor circuit?

Not that I've seen, on Iboats. I saw some site that had people making custom controllers for multiple trolling motors, speed and direction from a joy stick, but I don't remember where that was. MK and MG use PWM for their "digital" TM's, but the boards I've seen from them are encapsulated so no telling how they built the circuit board.

 

[Silvertip]

Re: Trolling Motor PWM design?

Why copy other work. Why not reverse engineer a factory setup then do your design. Copying someone elses effort may be a waste of time since you don't know how well it works or if it works.

 

[gm280]

Re: Trolling Motor PWM design?

Oh, I have a quite a few schematics of quality PWM (Pulse Width Modulation, okay a Digitizer as some companies commonly call it) circuits and when I do build one and work all the bugs out of it, I will post all the details, including the parts list, the PC board layout and where folks can buy all the parts if others want to build one. I will do a bread-board workup hopefully this week and then force it to the extremes in both heat, voltage and power draw to try and see where the limits are before posting everything. It will most likely be based on the very familiar 555 timer chip with MOSFET output devices for very low on resistances and very high current capabilities. I was just wondering if anybody else has done that already on these forums. I didn't want to duplicate their efforts. I am actually a little suprised that on a large open forum like this comment board that somebody hasn't already done that before, but I searched and found no results...

 

[fishrdan]

Re: Trolling Motor PWM design?

I didn't want to duplicate their efforts. I am actually a little suprised that on a large open forum like this comment board that somebody hasn't already done that before, but I searched and found no results...

Probably because MK and MG already have digital trolling motors, kind of like reinventing the wheel. MK used to have an add-on "maximizer" box, that was essentially a PWM powersupply for the TM. MK has their Digital TM's pretty low now with the EnduraMax line. Heck, BPS has them at $219 for a 40# digital TM with the rebate.

One thing I was thinking of toying with is, reducing the noise digital TM's make over speed coil TM's. Speed coil TM's make about the same noise through out the speeds, while digital TM's get noisy at 50% power then quieter towards slow and full speed, due to the choppy-ness of the digital output.

 

[glenn property of pam]

Re: Trolling Motor PWM design?

the noise is to do with the ammount of pulses so by adding additional timers they could be tuned out. This is common on vfd's running air-con fans and drives office staff nuts.
Im intrested in what ever you post (please included parts numbers) as im looking into a way of controlling multiple trolling motors as i want a boat that can run sideways in a forward current with out the boat turning or going forwards.

 

[gm280]

Re: Trolling Motor PWM design?

Probably because MK and MG already have digital trolling motors, kind of like reinventing the wheel. MK used to have an add-on "maximizer" box, that was essentially a PWM powersupply for the TM. MK has their Digital TM's pretty low now with the EnduraMax line. Heck, BPS has them at $219 for a 40# digital TM with the rebate.

One thing I was thinking of toying with is, reducing the noise digital TM's make over speed coil TM's. Speed coil TM's make about the same noise through out the speeds, while digital TM's get noisy at 50% power then quieter towards slow and full speed, due to the choppy-ness of the digital output.

fishrdan, the reason some of those digitizers (PWM circuits) get noisy is because they are probably changing both the frequency as well as the duty cycles as they move through the speed range. So as the frequency increases the noise should get a little less noticeable. I am hoping to keep a constant frequency (somewhere around 400hz but we will see) and just vary the duty cycle and therefore I can filter those noises out from being annoying to the operator by using filter capacitors/diodes across the output. These Digitizer circuits are not very expensive or complicated to build and I have no idea why they don't have them available on all trolling motors regardless of price or as an add on options to use with any trolling motor as an aftermarket item... It isn?t rocket surgery...

 

[gm280]

Re: Trolling Motor PWM design?

Can't say I've spent any time designing one, too many off the shelf ready to install to invest much time in it. But that's just me...

Bubba1235, I love designing such circuits and making them do what I want them to accomplish. I have a different approach to this issue. I could easily buy some PWM circuit and integrate it into my trolling motor hookup but I want a better design that I don't have to worry about. I usually over design so there are no edge limits on the component selections. For instance, the usual absolute maximum amperage draw would be around 50 amps max for any trolling motor but more realistically around 30 amps. So designing a circuit for 30 amps could cause problems in certain circumstances. So I'd use 60 amp MOSFETs so it won't be on the edge of its capabilities. I see too many manufactures use just the bare minimum capable (at best) components to make their products and know that some will fail if pushed to their limits for any length of time. So in essence, they design failure into their designs... I'm not that type of designer... I go for beefier components so I never have those issues.

 

[Silvertip]

Re: Trolling Motor PWM design?

Another case like this (and it actually relates to boats) was an American Company whom I worked for at the time, built some of the first tape players for automobiles. These were 4-track (yes you read that correctly) continuous loop cartridges about 8 inches square. If you are old enough to remember a TV hawker known as Mad Man Muntz of Muntz Stereo and TV, you will remember his hight-energy ads. He purchased of few of these "for evaluation" in readiness for a huge market release. Well guess what! Those units were evaluated in, you guessed it, Japan. The huge order never came and in short order the world moved on to 8-track and then Cassette. The US Manufacturer ended up selling many of those units to a US Boat manufacturer who will remain nameless. By the way, when the Boeing 747 was launched in 1969, it had a 16 channel audio system that used four of these 4-track cartridges for background music. 6 stereo channels and four monaural with the idea the one monaural cartridge would be replaced after each flight leg, end of day, etc and would contain news, weather and sports. Good ideal that never made much sense due to the manpower needed to continually record new cartridges. So -- better is not always a necessary nor a good selling feature if the price is too high..

 

[glenn property of pam]

Re: Trolling Motor PWM design?

a pwm board running a trolling motor is nothing new but the way you control the trolling motor may require a interface thats not available on a pre-made board. gps is a great idea but i have not seen a trolling motor yet that can keep a boat on a compass point (think it would require 2 trolling motors) so im intrested in how gm is interfacing with the board

 

[gm280]

Re: Trolling Motor PWM design?

a pwm board running a trolling motor is nothing new but the way you control the trolling motor may require a interface thats not available on a pre-made board. gps is a great idea but i have not seen a trolling motor yet that can keep a boat on a compass point (think it would require 2 trolling motors) so im intrested in how gm is interfacing with the board

:faint2:

Sounds as if you are looking for an auto-pilot type control capability. That takes a multi-receiver type GPS circuit to interrogate a minimum of at least three satellites to give any real positional quality and would interface with a trolling motor to not only maintain position but continually issuing feedback to adjust for errors. While that isn’t my idea for this simplistic PWM add on circuit, it does sound really interesting. It would take a microcontroller/microprocessor capable to run navigational protocols and a intricate program to use such mathematic calculations. Time bases would have to be synced up for starters to use the existing GPS system. So for a true quality trolling motor position/tracking/holding capabilities would be more than most any fisher person would be willing to pay for at this time... That would take a lot of intense R & D and an equally longer time to build and prototype. Maybe on the next project... :faint2:

 

[glenn property of pam]

Re: Trolling Motor PWM design?

:faint2:

Sounds as if you are looking for an auto-pilot type control capability. That takes a multi-receiver type GPS circuit to interrogate a minimum of at least three satellites to give any real positional quality and would interface with a trolling motor to not only maintain position but continually issuing feedback to adjust for errors. While that isn’t my idea for this simplistic PWM add on circuit, it does sound really interesting. It would take a microcontroller/microprocessor capable to run navigational protocols and a intricate program to use such mathematic calculations. Time bases would have to be synced up for starters to use the existing GPS system. So for a true quality trolling motor position/tracking/holding capabilities would be more than most any fisher person would be willing to pay for at this time... That would take a lot of intense R & D and an equally longer time to build and prototype. Maybe on the next project... :faint2:

hehe i want fish....big goliath grouper....... i know where they are under concreate blocks but to hold a boat so the person on the front is staying less than 2 feet away from a boat eating concreate block in a side/forward current takes a lot of effort. im thinking that 2 trolling motors one at front one at back could do this so i could just set the compass then move side ways with out the boat turning with the current. i said gps was a cool idea but its keeping the boat pointed in the same direction that is more intresting to me.

 

[gm280]

Re: Trolling Motor PWM design?

hehe i want fish....big goliath grouper....... i know where they are under concreate blocks but to hold a boat so the person on the front is staying less than 2 feet away from a boat eating concreate block in a side/forward current takes a lot of effort. im thinking that 2 trolling motors one at front one at back could do this so i could just set the compass then move side ways with out the boat turning with the current. i said gps was a cool idea but its keeping the boat pointed in the same direction that is more intresting to me.

Do you know where to get and TNT... Problem solved.

 

[bruceb58]

Re: Trolling Motor PWM design?

You can buy PWM controller boards for $5 all day and they don't use obsolete 555 timers that people used back in the 80s.

Personally, its not worth messing with them when you can buy PWM trolling motors.

 

[a124ave]

Re: Trolling Motor PWM design?

I am a retired Engineering Technician and worked for years reverse engineering older antiquated circuits and redesigning them to more useful and modern day components and better capabilities and more time between failures. However, I was just wondering if anybody on these boat comment boards has ever built a PWM trolling motor circuit? Yes I do have many schematics and could easily design one myself, but if somebody has already built one and did the R & D already and proofed it, I would like to get a copy or be pointed to the previous posting. So all you Electronic folks, put your thinking hats on and post your version with your proto-type results. Otherwise once I do the bread-boarding and circuit board design, I?ll post what I?ve designed and built with parts list and PC layout... Any takers? :happy:

Did you ever get this built?

 

[gm280]

Re: Trolling Motor PWM design?

Did you ever get this built?

Odd that you asked that at this time. The answer is yes and no. I haven't actually built the circuit YET. But I have designed the circuit board and layout. I am in the process of building three or four boating circuits presently. I designed the PC boards for them now and will be making the boards real soon and testing. I did base my PWM circuit on that old 555 timer simply because it does the job perfectly and is cheap and satisfies all my requirements. Simplicity and reduced parts counts are the driving issue with any circuit I design. The less part count the better the reliability there is. I could design some very complex design for a PWM circuit, but why? I can say that I'm looking at the IRFZ46N and RFP70N06Power MOSFETs as the final motor drivers. Haven't decided yet as to which one. Both have a very low Drain Source ON resistance so that means lower heat problems too. I'll post as I get them built...

 

[bruceb58]

Re: Trolling Motor PWM design?

Simplicity and reduced parts counts are the driving issue with any circuit I design. The less part count the better the reliability there is.

That's why you would use something even simpler like a PIC controller or similar. Nobody uses a 555 timer anymore.

Or just use one of the hundreds of PWM circuit boards already designed, assembled and selling for a few dollars.