Showroom **RIP** - 6DOF project using 12v DC Motors, Sabertooth 2x60's (was MM's) and Arduinos + OSW

They are 15:1 @BlazinH.

Just to check, did you check all your MMs separately before now? DOA, or did they fail during use? I'm certainly going to check all mine before they are wired in place. Have found one DOA so far.

I was a bit stupid and wired everything up without checking. I have learnt a big lesson here to check before.

When I turned them all on with no motors connected they all turned on fine no issues it was as soon as I connected motors 4 tripped out straight away.

I have one that is splitting the positive and negative on one half of the mm causing an instant short with the other side of the mm. Some show voltage output but as soon as you connect the motor it just drops the voltage to zero. Some a1 a2 b2 work but connect b1 and it shorts out or it turns the motor very slowly. All different combinations of problems lol

Lots and lots of different issues all down to the vhsp30 chip or whatever it's called.

Cheap chinese crap unfortunately you get what you pay for. And I left good feedback before I checked them so trying to get a refund or replacements is being difficult to say the least.

I used a oscilloscope on the output of a suitably configured ARD/MM to test them. From @SilentChill results will also make sure to test them individually on a load (likely just use a free running spare motor). I will post up my results when finished.

Your sim is really cool looking, good luck with the part your looking for, regenerative current can be dangerous that's sure......

Ok I finally give up with these MM's they are all shite . Think I will just have to order more as the seller is messing me around saying he has no stock even though it says they have 952 in stock.

Maybe a few weeks till I get it sorted

From which store you did buy the MMs? I am sorry that you have so many issues.

I wish you the best of luck with those @silentchill! I really hope my opinion is wrong (it wouldn’t be the first time) but I think you are going to have many issues getting those to work well with that ratio. My belief is that you will either need quite a bit more power or a higher ratio gearbox when under full load. Have you tested the torque these put out using your current levers length so calculations could be done to verify validity?

@SilentChill sorry to read about all the problems with the MMs.

Is it possible to use Sabertooth instead? They seem to be more reliable.

@BlazinH my very technical torque test was me standing on the lever with one foot (all my weight);whilst the motor was doing the sine motion and it worked ok .

My MM's are the problem and I'm pretty sure it will work once I have dual MM's per motor. Especially with 6 motors taking the weight of it all

@Leo Burton the main issue is the cost and that I have no experience with them either. I'm very confident using Ards and MM's I know what I'm doing I think lol

@SilentChill , I totally understand. Cost and stick with what you know.

How much are the MM's?

I think 1 x Sabertooth module can run two motors (depending on specs etc..) So you would only need three.
But you need 2 x MM for each motor with those? Worth looking into cost perhaps?

Might be worth sending Dimension Engineering an email to ask about compatibility. They look a look easier to setup than the MMs as well.

Just a suggestion, if the next batch of MMs also arrive faulty.

Well I can get 12 MM's for the price of 1 sabertooth which is a massive difference and the MM's if they actually work properly can handle a lot more power

Wow, yes that is quite a difference in price!

...even if some samples will be D.O.A

@Pit I bought the MM's on Aliexpress sold by Shenzen Yida Technology Co. and the seller for them is Jeney Gao

I have 19 more coming so will have to see how they do i spent a little more with someone with more orders so will have to see how it goes

The biggest difference between MM’s and sabertooths is the MM’s are h-bridges only while the sabertooths are microcontrollers with h-bridges on them. MM’s can only be controlled with a varying PWM signal whilst sabertooths are controlled via other methods. Below are the key talking points for the sabertooths (2x60).

Yes, they could be considered pricey compared to MM’s. But for me, the reason I use them is to avoid this:

But I guess as long as you are able stay within the “sweet spot” on the MM’s you are good to go!

Btw, one sabertooth can control two motors speed and direction using simple serial mode with only one line of code on an arduino; Serial.write(byte). If a Mega is used, it has 4 UART’s. So one can be used for communications with your PC leaving three others free to control up to three sabertooths and 6 motors.

I agree with @BlazinH. The situation is a mess. We could use the MMs as a cheap and versatile motor driver but if so many are faulty I think I will switch to the Sabertooth next time. In your case @SilentChill 3 Sabertooth 2 x 32 should be enough strong to power your motors. Three of them cost totally $375 instead of $120 using MMs. If you add all the faulty ones you spent more than 200 bucks. The Sabertooth is way more expensive but less worry for sure and Dimension Engineering offers a great warranty :

"Dimension Engineering offers a full 1 year manufacturer's warranty. If any product fails within one year of the purchase date we will replace the product at no charge. After 1 year we will either repair the item or the item can be replaced for 50% of the retail cost."

I just want to say Hi ...
"HPMC" High Power Motor controller H-bridge using N-MOSFETs