Model boat DIY speed control problem

sarahMCML

Joined May 11, 2019
352
Unfortunately I do not have a scope.

So pin 7 and pin 8 will each get their own diode and the anodes connected to R3/R5 as Alec said.
Sorry I couldn't get back to you sooner. Try it with the 2 diodes, but it may not pull the R3/R5 junction down low enough, in which case just connect them as shown in your original circuit, i.e, 7 & 8 together then to R3/R5.
 
Try it with the 2 diodes, but it may not pull the R3/R5 junction down low enough, in which case just connect them as shown in your original circuit, i.e, 7 & 8 together then to R3/R5.
I hope you are right, after all it would prove that the schematic is actually correct - I will go back and look at all the posts, somehow I had it in my mind that it didn't work originally with 7 and 8 connected together but I may well be wrong about that...

Even if it does work with two diodes, I'd then try going back to the IC completely back in its socket without the diodes - the layout joins 7 and 8 together. If that works, it's the quickest way to check if I was wrong in the first place!
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
In the instructions it said do not solder pin 8 and pin 10 of the 409. Yet the schematic showed them connected. That is the reason I started this thread. Now pin 10 is soldered to power the 409 and pins 7 & 8 are butterflied out so I can test with diodes which I am working on now.
 

Alec_t

Joined Sep 17, 2013
14,206
I'm still interested in knowing for sure if there are any active pull-ups of pins 7 and 8 within the '409 (but I don't believe there are). While you have pins 7 and 8 butterflied out can you move the joystick to 'forward' and measure the voltage from pin 7 to ground (a) when a ~10k resistor temporarily connects pin 7 to +5V and (b) without that resistor. Then repeat these measurements with the joystick moved to 'reverse'. What are the four values?
 

Alec_t

Joined Sep 17, 2013
14,206
The post #66 results (thanks for those) convince me that there is no active pull-up on pin 7 (or 8), but I would have expected something >0V for one of the 'without' measurements, albeit dependent on duty cycle being outside the dead band.
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Sarah. You’re saying connect pin 7, pin 8 directly to R3/R5 with no other component? No diode or resistor?

Just being sure.
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Still have the pins butterflied and used jumpers. Both speed controllers operate in both directions like they should be! I’ll put the pins back in the socket and solder pin 8 and retest.

The strange thing is why he said not to solder those two pins. It’s pretty specific where he put that in the instructions. Will never know why that was since he passed away. His sons allowed me to take many of his hobby related stuff. I have a whole cabinet of electronic parts, brass, plastics, paints and other stuff used for model building. I’ll have part of him in the future boats that I build.
 

sarahMCML

Joined May 11, 2019
352
Still have the pins butterflied and used jumpers. Both speed controllers operate in both directions like they should be! I’ll put the pins back in the socket and solder pin 8 and retest.

The strange thing is why he said not to solder those two pins. It’s pretty specific where he put that in the instructions. Will never know why that was since he passed away. His sons allowed me to take many of his hobby related stuff. I have a whole cabinet of electronic parts, brass, plastics, paints and other stuff used for model building. I’ll have part of him in the future boats that I build.
If you now have it fully back together and working, you are now the resident expert on that circuit for your club. You should write up some new notes on how to test and trouble shoot the circuit for any future users. Best wishes!
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
I have them both reassembled and tested. Ready to go in the boat when I am at that point. With the few of us left in the club I don’t think anyone else has these. And knowing the skill level of who is left, they would not tackle this. How unfortunate. I will be sharing with the group next week assembling and troubleshooting them and how invaluable a forum such as this is. Thank you all for your expertise and helping me out. I will post a few pictures of the progress of this boat when I get the workbench cleared.
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
We have a museum near us called InfoAge in Wall Township NJ. They have an area where they show progress in the age of communication from the late 1800’s to present. The main building is called the Marconi building which was occupied by Marconi himself. During one of my visits, talking to a staff member, he said they could give me a Textronics scope, they have spares in storage, people unloading older stuff. I declined as I would hardly use it and I don’t have much room. Always had it in mind to have one, but would never use it.

Neat place to visit.
InfoAge web site
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Here are some pics of the boat these speed controls will be going in. The real boat is 85 feet. The model is 42.5 inches which is 1/2 inch to the foot. The real boat no longer exists so I have to build it from pictures and my knowledge of boats.

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The deck planks are individual planks I had to cut, stain and glue to the sub-deck. The railings are 3/32 brass tubing soldered at each joint. Each joint has a 1/16” pin to help hold the rating together.

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More railings pics. The hull is basswood planked on a plywood frame. The basswood has been epoxied with a layer of cloth with epoxy resin. The feint plank lines you see on the hull were individually scribed into the epoxy to simulate wood planks.

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The interior framework was designed by looking at the pictures and knowing how to construct a model boat. This is not a kit.

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Besides this model I have another party (fishing) boat that is bigger that I built 10 years ago.

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Also built an offshore powerboat called KAAMA. I clocked it at 45 mph.

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Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
And have two submarines that were made to dive. Had to buy the components individually and incorporate them into the boats.
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Non scale lights to run at night.

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