@RR, I think it's important to realize that we're not using the battery to power anything. The power supply is doing all that. The battery is just there to dump the extra power into that the Sabertooth generates. That's why the PS is first in the circuit and the battery is second. The diode between the ps and the battery keeps the battery from back feeding the PS and the regen power from the Sabertooth from tripping it. Best of both worlds!

Excellent, thanks Dave. I haven't done any circuit design since high school 30+ years ago, so I wouldn't have been able to figure this out, but your diagram makes perfect sense. Another thread going in my "this will be useful" folder.

Alan

I cant thank you enough Dave

Please excuse my ignorance, I'm an electrician by trade but electronics knowledge is a little limited, on your schematic, the supply voltage is 24 volts and mine will be 12 volts. Does this alter any of the values of the other components? With the signal from the EZB, is that controlled via your script?

Ps. I have been following your progress on this forum and the B9 Builders site for a while now and I am to say the least, in awe of your B9. Blows my mind!

My build is not as far along as yours, I hope to have the Torso in a week or two from a local B9 vendor, Its been a long time coming, over 12 months. I have built the head section from the collar up, the legs are finished, I have a complete aluminium tread section ready for paint and pretty much all the other goodies to go inside it and the Torso. I hope to be able to spend some serious time on him over the Christmas break.

I've been a bit slack with the pictures. I will need to take some more and post them.

Steve

Steve, the parts I used will work fine with 12v also. In fact I switched my power supply over to 12vdc and it works just fine. One thing that may be of a concern is if your using a V3 or a V4 EZB. The voltage off the signal pin of the digital port on a V3 is 5v and 3.5 on a V4. If you have a V4 reduce R2 to a 10K resistor or this circuit won't work.

Dont worry about not knowing stuff like this. I'm no wiz kid either on electronics. I'm also an electrician but I don't work on the complex level you work on. I'm a distribution power lineman and work on building and maintaining high voltage power lines. So electronics don't really come natural to me. I just study and build what I need.

Looking forward to seeing what your working on !

@Alan, Glad I was able to help and repay you for some of the help you've given me.

Dave, I am planning to use V4 EZBs. I have ordered two but I am still waiting for them, soon I hope.

I'm sure, when it comes time, I will have to take you up on your offer of help setting up the Sabertooth / Kangaroo

Thanks again mate

Hi Dave,

I have made some alterations to your schematic as per your Edit, I think I got it right. Could you please look it over and let me know? I have circled the changes in red. Note - I will be using an EZB4

Does the diode D3 need to be rated to carry the full load of the motors? I think the 1N4004 Diodes are only rated to 1 amp.

Kind regards

Steve

Yes Steve, that looks perfect! Thanks for updating the sketch. What program did you use?

The diode D3 does not need to be rated any different then the other diodes as far as I can tell. It's not carrying any of the motors load. It's only blocking the regen voltage of the Sabertooth from back feeding into the control circuit.

EDIT: Steve, I have to apologize. Thanks for bringing this up. It seems that you've found a weak link in my circuit. My first answer above was premature and given on the fly when I was at work and distracted. After thinking it through I'm sure you're right. Not only D3 is in question but also the other two (D1 and D2) needs to be rated for either the amp draw of both motors being ran from the Sabertooth or for what the total capacity of what the Sabertooth can draw. In this case the 2X12 Sabertooth is capable of pulling up to 12 amps. You'll want to add .25% for safety so you'll want a diode able to handle 15 amps forward current. However if I want to design for my motors amp draw which is 4 amps then I would only need to have diodes that are rated for over 5 amps which includes the safety overhead. I guess its a choice but it would be safer if you design for the capacity of the Sabertooth. The Mosfet at Q2 is plenty large enough. Its rated for 19 amps and the predriver Q1 is behind Q2 so that is OK. Maybe the reason I haven't seen any problems with these 1 amp diodes burning or even heating up is because my motors don't pull more than a couple amps on startup and then drop off when running steady. Also they only run for short bursts of only up to 10 seconds at most. Still, I'm going to have to replace them with something that is rated for more amps. If you need a diode more than 5 amps it may need to be mounted on or with a heatsink. Again, very sorry for the amiture attampt at circuit design.

I've found time over the past couple weeks to work on my Kangaroo/Sabertooth powered elbow joint in my B9 arm. It's going to be lifting most of the weight and I need it to be smooth, position and speed controlled by a Kangaroo/Sabertooth through the EZB. The speed needs to be human like. I've made some good progress and have learned more about setting up the Kangaroo for lifting heavy robot arms. My biggest problem was after a successful AutoTune when the arm would move to a desired position and hold it would shake and jerk like a drunk with the DTs. Using the DEScribe software I was able to get this adjusted out so it does not happen. I found that the setting in the Control Tab for Position Deadband (not the Deadband in the All Input section) needed to be increased to keep this from happening. Also under the Advanced section the Response Time needed to be increased also. DE said for vertical lifting like a robot arm the High Speed Gain needed to be changed to Zero but I did not see any noticeable change once I did that. However I'm still fine tuning the settings so I can have a more fluid motion and stop. A big holdup is that there is no documentation on how the settings in some of these control settings windows effect the behaviour of the motor. They are auto set by the AutoTune process and they only say they don't need to be changed in most cases. Well, in my case (and maybe yours) they do need to be changed.

Also I found a real good product that works great for me. It's a SoftPot. I mentioned it before. It replaces a regular 10K pot and is flat and round. I'll try to add a link later but if you search the WWW for Softpot you'll find it. SparkFun sells them but they are out of stock right now. I got mine from Mouser. They make linear and round softpots. I have the round version mounted between the motor and homemade hub I built out of 4" alum angle. A separately bought stylist presses down on the Softpot and send the changing voltage reading as the motor shaft turns back to the Kangaroo just like a regular pot. It works great and takes up no room at all. Perfect for tight places. HOWEVER: you need to add 1K resister to the positive leg or it may overheat when pressed improperly in the wrong place. Also I got a better reading using 5vdc and this resister then the 3.5 that the EZB's ADC ports put out. When attached to a Kangaroo X2 this is not a worry as it supplies 5vdc to any feedback device attached to it.

More to follow. Hope this helps. Dave Schulpius

Thanks Dave,

I simply opened the diagram in paint and altered it from there. Pretty low tech

When making alterations to the settings in the Kangaroo, is this where the TTL to USB cable comes in? How is it connected? I will have to have a look at the DEScribe software and figure that out too.

Awesome work on your B9 arms by the way, I cant wait to see how they turn out. If its anything like the rest of your robot, then they will be a masterpiece in engineering. I can only imagine how hard it is to get fluid human like movement.

Steve Neal