Building a Dig Controller for you MOA guys.

[heyok]

This is the beginnings of a Dig Controller for MOA rigs. This circuit will watch a three position or linear channel to select the dig mode.

This is how the positions are decoded:

1. Front Dig
2. Four Wheel Drive
3. Rear Dig

If an axle is in dig mode, its motor is shorted (puts the brakes on) and either the red or green LED will be lit.

My goal is to keep this as small as possible. The circuitry will be dead bug style (no circuit board) and most of it will likely be covered in heat shrink and sealed with silicone to waterproof it.

It is still very ugly, remember this is a prototype, but I wanted to share the progress.










Still lots to do. I will do more as I find the time.

The circuit is really very simple. There is a PIC that decodes the servo signal and then it activates one relay or the other. There will also be a MOV (transient supressor) for both motor feeds to help with the relay contact life.

I plan to leave a few inches of motor wire - maybe 12 to 16 gauge - for each of the motor connections and esc connection. I will put a female Deans style connector for the motors and a male Deans style connector for the ESC to plug in, but I want your input here. Would you prefer it not to be connectorized or some other style of connectors?

[aaugman]

Cool you should sell a lot of these, Punk dig's are great but their customer service and availability is up to cr*p,

Make a bunch of them if they work well and you should sell em all.

I would make sure that they can handle the amp load that the motors put out.

[paintballer9876]

I prefer bullet connectors since the are small and allow me to easily switch polarities to the motor.

[heyok]

Originally Posted by paintballer9876

I prefer bullet connectors since the are small and allow me to easily switch polarities to the motor.

Sounds good. That would probably work if I supply the bullets because I have a box with a bunch of incompatible sizes of them.

Thanks for the input!

[heyok]

Originally Posted by aaugman

Cool you should sell a lot of these, Punk dig's are great but their customer service and availability is up to cr*p,

Make a bunch of them if they work well and you should sell em all.

I would make sure that they can handle the amp load that the motors put out.

The amp issue is an interesting one. A higher current relay takes up more space than a lower current one. If someone has a dig unit already, it would be interesting if they could post the model number of the relay being used so we can see if there is something more suitable.

The relay you see in my pictures is a Schrack RTD14005 with contacts rated at 16 amps.

I have some 20 amp relays but just one of them is larger than two of the Schrack RTD14005

What wears out the relays the fastest is switching them when they are under load. That is probably not how most people would drive.

[Seth]

So in 4 wheel drive both relays would be on along with both led's ?

[heyok]

Originally Posted by Seth

So in 4 wheel drive both relays would be on along with both led's ?

Actually, when in 4wd both LEDs would be off. This is when the relays are in the "Normal" position (unenergized) and the "Normally Closed" contacts are used.

So if you like, green could indicate when the front axle is allowed to turn and red when the rear axle is allowed to turn (or the other way if you hook the motors up to the opposite outputs). The LEDs aren't really vital, but they are nice to confirm that the circuitry has received the command to go into dig mode.

[ecoli]

I'd leave the wires bare Al. Typical way most controllers come nowadays. Allows the user to decide what he wants to use (bullets, Deans, powerpoles, Tamiya !)

[bob1961]

i used to run a shafty and most likely going MOA soon....i found the rear free wheel more useful then rear wheel locked....watching other guys running MOA rigs i seen them having trouble when the rear or front tires was locked up solid and could see the benifit of free wheel front and rear on MOA rigs....that is why i haven't gone MOA yet i just don't like dig without free wheel abilities....i also haven't read and fiddled with my DX3R controls, mixing and such yet as there was no need with a shafty....so unless i'm missing something does your product have or will it have free wheeling mode....i gotz lotz to read up before going MOA , thx........bob

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[Airmaxx23]

I'd be interested in one of these when they are done. I would leave the wires bare since everyone has their own personal preference when it comes to connectors.

[paintballer9876]

Originally Posted by bob1961

i used to run a shafty and most likely going MOA soon....i found the rear free wheel more useful then rear wheel locked....watching other guys running MOA rigs i seen them having trouble when the rear or front tires was locked up solid and could see the benifit of free wheel front and rear on MOA rigs....that is why i haven't gone MOA yet i just don't like dig without free wheel abilities....i also haven't read and fiddled with my DX3R controls, mixing and such yet as there was no need with a shafty....so unless i'm missing something does your product have or will it have free wheeling mode....i gotz lotz to read up before going MOA , thx........bob

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The hardest part would be you would have to sacrifice one of your digs to do this or have a radio with 4+ channels. The issue is the motor even with no power will lock itself just a little bit making so its not a true free wheel. True free wheel is not possible with moa unless you can have a mechanism that moves some gear in the transmission so it is no longer in interaction with the motor. This would cause all sorts of durability issues since if it gets stuck and is only partially engaged it will result in stripped gears.

[KBrog]

Cool Item you are building.

[forbid89]

Out of curiosity what model PIC are you using?

[sabohead]

I personaly dont care what it looks like as long as it works!! Purple w/pink pokadots I dont care. I like what you are doing and would love to test one out for ya!!

[Reflection]

Originally Posted by ecoli

I'd leave the wires bare Al.

I agree.....

I need a few when they are ready.

[aaugman]

punkrc

http://www.punkrc.com/index.php?main...im0uocfjlkugd6

[Airmaxx23]

Originally Posted by aaugman

punkrc

http://www.punkrc.com/index.php?main...im0uocfjlkugd6

He's offering an alternative to Punk RC's dig since there are people who are not happy with Punk's service (like myself) and need another option.

[bob1961]

thx paintball that's what lines i was kinda thinking along......bob

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[EeePee]

Originally Posted by heyok

What wears out the relays the fastest is switching them when they are under load. That is probably not how most people would drive.

Pretty sure most people switch while hitting the gas. That was a big bonus to electronic digs over mechanical (on shaft drive trucks).

Originally Posted by Airmaxx23

He's offering an alternative to Punk RC's dig since there are people who are not happy with Punk's service (like myself) and need another option.

But there are probably hundreds or more happy people with them. Always a few to complain, never many to compliment.

[Airmaxx23]

Originally Posted by EeePee

Pretty sure most people switch while hitting the gas. That was a big bonus to electronic digs over mechanical (on shaft drive trucks).



But there are probably hundreds or more happy people with them. Always a few to complain, never many to compliment.

You're right, it's the same with everything, people rarely make a "I'm happy with _______" post, it's mostly people who have had problems, like myself.