Adding wireless remote to a old Autohelm 3000

[weavis]

Originally Posted by desdestiny

I still cannot upload the images, I even tried creating a word document and cannot upload the word document file
How do I attach images?
Des

https://www.youtube.com/watch?v=zk5lMX3NuMU

[Greatketch33]

I'm very impressed with SC work. I'm not an engineer but inspired to learn this topic. I have a auto cp3000 auto pilot that is wheel driven.

I'm interested in learning this topic in an effort to make mine wireless. I solo sail often and having some connection from the bow to the ap would be huge.

GreatKetch33

[sailorchic34]

Originally Posted by mrm

Yes, I see how that unshielded field can be a problem. How about a small modification and getting rid of relays altogether?

Working with a few assumptions I made a schematic of how it might work. Your current (assumed) setup is drawn on the schematic. For clarity only a single input channel is shown. If a remote receiver and Autohelm share a common supply it could be possible to use a relay drive signal TP2 directly to drive Autohelm input TP1.

The logic side of the autohelm is running at 5V that powers four darlinton power transistors (two for forward and two for reverse , 2 PNP and 2 NPN) to drive the 12V motor.

I'm thinking removing the relays and adding opto-isolators after I get the diodes installed to test the 10 degree side, since it's all low load signals. It's a minor annoyance when turning to starboard but it does turn and hold a heading.

[sailorchic34]

Gee already to the Mark II remote.

Just ordered this: IC2262-2272-4-channel-wireless-remote-control-kits | eBay

Which uses opto isolators instead of relays. It's cheaper and smaller. Still needs diodes. It will require soldering though. It will be a month before it's in and I get it.

Basically you find 5V and ground on the board (near the 5V regulator (I'm thinking). Then data pins one and two go to port and starboard and three and 4 pick up the 10X line with diodes to data 1 and 2. Easy peasy. Still going to finish the mark I remote and then play with the mark 2.

[CtrlKX]

Originally Posted by desdestiny

Hi from another engineer. Most interesting development.
Some years ago we had a similar waterproofing requirement for a remote control operating on 433 Meg. These are standard car remotes operating on this frequency, and typically use rolling code to synchronise remote to receiver.
We designed and tooled 2 plastic mouldings to replace the traditional remote outer parts, and designed and tooled a silicone seal which is sandwiched between the two ABS mouldings.
The Silicone membrane covers the PCB and protrudes through the top cover to depress the buttons.
It also has a wall bracket to hold the remote inplace.
Our application was a remote control handset to operate a pump for a Jacuzzi.
We have this available for sale if you like. It is waterproof and works underwater.
Des

The Remote also floats in water handy if it ends up over board.
View more details regarding the remote here. Spa-Key
A PDF file regarding the receiver http://www.kitsrus.com/pdf/automicro.pdf
I doubt the remote will work with different receivers due to the rolling code technology which uses a manufacture ID in the algorithm.
We would be happy to sell both these parts if interested.
I have never seen anyone else selling a floating water proof remote using this 433 MHz technology.

I also agree with using opto-isolators to interface the receiver board to the Autohelm main board. It may be simpler with a transistor, but opto's give that assurance of isolation.
FYI- I work with desdestiny
Regards, Dean.

[RaymondR]

I love these autopilot projects and Sailorchik34 appears to be a woman of many talents.


I had one of those old Autohelms but kept blowing the H bridge Darlingtons when the wheel pilot drive burnt out motors or I accidentally switched it on without it connected to a motor. They were fairly easy to replace (unlike the mosfets in the Raymarine ST4000) but eventually I burned out the fine tracks to the base drive of the transistors and having a steel boat decided to upgrade to an autopilot with a fluxgate compass and readout at the wheel.


My big thing is building the wheel pilot bit. The first was the original Autohelm one after I stripped the nylon gears, I pulled the motor and gear box out of a Chinese battery drill and adapted it, the next was two Chinese drill gearboxes driven by the original Autohelm motor. The existing one uses a 24V motor from an electric bike and the one I am building now is chain reduction using a 12V motor from an auto radiator fan.


Good work babe, great to see other budget cruisers work on here.

[ErikFinn]

Sailorchic, you just inspired me to have another go at repairing my old Autohelm

[sailorchic34]

Originally Posted by RaymondR

I had one of those old Autohelms but kept blowing the H bridge Darlingtons when the wheel pilot drive burnt out motors or I accidentally switched it on without it connected to a motor.

It's real easy to burn out one or more of the darlintons. Just turning the wheel with the motor engages but not powered can do it as I found out. This as the 12V motor can generate a reverse pulse.

But the darlingtons are easy to replace.

I'll remember about using a drill motor should my autohelm motor bite the dust.

Originally Posted by ErikFinn

Sailorchic, you just inspired me to have another go at repairing my old Autohelm

One note for those first timers. Don't remove the screws around the rudder adjustment shaft. They hold the tiny BB and springs for the detente action on the rudder control.

Once all the board screws are removed, slowing push the rudder shaft while moving the board. Be sure all the screws are out.

Then you need 2 NPN and 2 PNP darlintons. I ordered 4 of each to have a spare set.

Then it's simple a matter of crosschecking the old part# with the New Darlinton part#.

Having a desoldering iron helps lots too.

[CtrlKX]

Do these H-Bridge driver circuits not have clamping diodes to divert the back emf around the darlingtons ?
A good drive circuit for any DC motor should use diodes across the emitter and collectors of the output transistors. You can always add these, space permitting.
MOSFETs are a better choice now for the output stages of H-Bridges, though I can understand that older circuits would have used darlingtons, but today's MOSFETs are fairly rugged.
Depending on the circuit you may well be able to replace the NPN and PNP darlington transistors with N-channel and P-channel MOSFETS. Another bonus with the MOSFET is the built in reverse diode they have. Usually you do not need the external back emf diodes anymore.

[RaymondR]

Originally Posted by CtrlKX

Do these H-Bridge driver circuits not have clamping diodes to divert the back emf around the darlingtons ?
A good drive circuit for any DC motor should use diodes across the emitter and collectors of the output transistors. You can always add these, space permitting.
MOSFETs are a better choice now for the output stages of H-Bridges, though I can understand that older circuits would have used darlingtons, but today's MOSFETs are fairly rugged.
Depending on the circuit you may well be able to replace the NPN and PNP darlington transistors with N-channel and P-channel MOSFETS. Another bonus with the MOSFET is the built in reverse diode they have. Usually you do not need the external back emf diodes anymore.

It's quiet a while ago but I seem to recall the Darlingtons were marked BDW 93C and BDW 94C but my old memory aint what she used to be.

As far as I remember there was absolutely no protection of any sort. I seem to recall that the tracks which burnt off the board ran directly between the output of a smaller base drive transistor to the base of the Darlingtons. I seem to remember having to replace the smaller transistors and some resisters on occasions.

When I got sick of repairing the Darlingtons and base drive transistors I actually thought about bootstrapping a mosfet H bridge motor drive circuit by taking gate drive from the Darlington H bridge with a fairly high value resistor across it's output.

My next autopilot project is to try to get a wifi connection between my numerous computers and tablets and the NMEA 0183 network on the autopilot I am finding that the usb connectors on the computers are not that enthusiastic re life on the bounding wave.

[CtrlKX]

The BDW93C/94C are a nice device. http://www.farnell.com/datasheets/1689726.pdf They are built with an internal back emf diode. I suspect though that the response time of this diode may be too slow to fully protect the device. High speed external diodes would have helped here. Especially if the autohelm circuit gives any PWM signal to the motor.

When the diode does not conduct quickly enough, the energy is still looking for somewhere to go, quite often it finds a way through the transistor itself, often shorting the base to a collector, hence high current returns out the base frying the driver stage and blowing the lighter weight tracks in the process, and perhaps some resistors...

Good idea with boot strapping MOSFETs. You may be able to just replace the darlingtons with MOSFETs, as the pin polarity and position is usually the same. Base=Gate, Drain=Collector, Source=Emitter. Maybe tweaking the driver stage, however providing the gate of the MOSFET with some current at the start of switching is a great idea to prevent the gate capacitance conducting both top and bottom devices at the same time. The existing driver circuit would do this, just have to make sure the voltage swing is enough, This may require changing collector pull ups and downs in the driver circuit, but you really should try to draw the driver circuit out on paper to know for sure.

Actually your idea of using the darlington H-Bridge to drive external MOSFET H-Bridge is still a great idea! This ensures quick switching ON & OFF, and stopping gate capacitance slowing it down.

Good idea regarding the avoidance of USB connections in those environments WiFi is what I would call more solid state and less moving parts always makes a more robust system!

[desdestiny]

Further to the remote control and the waterproof casing we have....
The Microchip device which we use and transmitter has 4 buttons.
What few people know is that you can get 10 signal output from this device by pressing 2 buttons at a time - in other words you can get 10 different control functions from the basic 4 button device.

Also the rolling code synchronisation prevents 2 remote devices from operating
a function on another yacht.
Button 2 and 3 may be port and starboard, button 1 and 4 may be winch up/down.

Press button 1 and 2 together can control other devices, 1-3 another control.


Thanks for the info on how to upload an image file

[sailorchic34]

Well OK, I was wrong. Diodes are NOT required.

While I thought the 4th line was a data input, it was really another high / + power. I found this out after trying a diode on one leg, which did not work at all how I though it would.

So after some trial in error this is what I have.

On the ribbon cable starting at the end opposite the red #1 line we have:

#4 = 10 degree turn
#3 = turn to starboard
#2 = 1 degree turn
#1 = turn to port

Connecting #4 to either #1 or #3 does a 10 degree turn to the indicated direction. Connecting #2 to #1 or #3 does a 1 degree turn to the indicated direction.

On the relay card from left to right you have the following connections
See photo below, relays numbered 1 to 4 with pins a,b,c on each relay.

1A #1 signal wire and daisy wire to 3A.
1B #2 signal wire and daisy to 2B
1C No connection
2A #3 signal wire and daisy wire to 4A.
2B #2 signal wire (daisy chained from 1B)
2C No connection
3A Wire connected to 1A
3B #4 signal wire daisy chained to 4B
3C no connection
4A wire connected to 2A
4B wire connected to 3B
4C no connection.

You will need to solder a 3" ish length of wire onto #4 signal wire so it will reach the 3B connector. 22 gauge wire is all you need. I stole some from the Garmin plotter cable that was not being used. (I'm frugal).

While the relays effect the heading sensor when energized, it's of such short duration that the boat does not have time to respond before the wheel turns in the correct direction. Oddly the direction turned by the relay changes depending on heading. But it's very minor.

I wear the remote on a lanyard around my neck. A lovely hack for those still using the old Autohelm 3000.

[sailorchic34]

Last comment: I took the remote apart to check the battery type and what do you know. It has a water proof membrane under the buttons and a seal on the cover. Pretty sweet.

[darylat8750]

Thanks SailorChic. Another practical thread.