Lynxmotion Tech Support

So a cap between the positive and ground voltage, and a second cap between ground and signal?
I assume since all servos share the same voltage lines i only need 1 cap for the whole array.
Then each servo gets an individual cap for the signal lines.

I found separating the entire bot from the antenna with a simple grounded foil sheet, didn't even work, as the RF interferes with the ground. It caused all servos to freak.

Would a 0.1uf cap work? i have plenty of ceramic capacitors i can salvage, just let me know what uf to use, or what number i should look for on the capacitor. ie 104's for 0.1uf.

My budget wont allow for a new camera for a few months, so if i can get this 900mhz camera working, awesome.
Having a bit of trouble getting the shielded wires.
Been using wires i salvaged from other stuff, but getting enough, and the right size is becoming a pain in the butt, but that's my problem.

I'll probably be redesigning most of the bot in a little bit, after i get more of those MG90 servos, small and super strong. MG90S's might work, the S's are $1.50 cheaper, but they have sleeve bearings vs the MG90's ball bearings. I don't know if it makes that much of a difference 2kg/cm sleeve versus 2.2 to 2.4kg/cm for ball bearing.

.1 caps near the power pin, if you have a few servos, you can even put them right across the bottom of the connector. Put .001 caps on the servo data lines, (test), shouldn't affect the data. Put caps on the camera power lines. Are the camera and servo power supplies isolated? Have you grouped the servo lines together as much as possible, and kept them near the metal chassis? The camera lines could also be routed close to the chassis, (put away from the servos). Don't forget to ground one end of the braids.

Alan KM6VV

Thanks.
I'll try a 0.1uf(104) cap on the power, and .001uf caps (102's) on the primarily effected servos and test that.
As far as the braid, i'm still having trouble finding the right kind, it's not as easy as i originally thought, but no problem, i'm sure i can find some.

The camera is on completely separate power at the moment. They were originally supposed to share power, but i think i need to get it working as is, before i re-modify it again.
I returned the camera back into it's original unmodified state.

I'm still a bit sick so i'm taking my time working on it. Robots don't like to be sneezed/coughed on.

Edit:
Well... it didn't work.
The 104 capacitor over the power helped a tiny bit. but the 102's between the grounds and the signal wires did nothing, it may have even made it worse.

The shielded wire (i tested it on 1 servo and only had 1 servo connected) cut the interference down to about 25-35% of what it was.
Which is pretty good... but not enough. For it to work i'd need to get rid of the interference completely.
Since the camera gets attached to the arm, and this is a tiny robot so everything is within just a couple inches of eachother. It just didn't work.
The interference of having the camera within 3 inches of the servo caused it to glitch. I don't have an oscilloscope to do other testing.
If anyone has a 1.2ghz camera, mind testing it near a few active servos, see if it glitches at all?

Edit again:
What about ferrite chokes? I see them on just about every device, wouldn't those help a little?

Edit some more:
Well ferrite chokes helped a bit. 1 servo seems pretty stable now. The wires are MUCH less sensitive, but i don't have enough shielded wire to work in addiction to chokes, but the chokes seem to reduce the wire sensitivity by like 80%.
Does the color of the ferrite choke matter? I'm salvaging them from old fried motherboards, so i wanted to know if the color matters.
The servo with the black painted choke seems to be doing a little better than the servo with the green painted choke.
They are really hard to get off without breaking them.. Like 5+ capacitors in the way.

I'm only able to get 3 wraps with ferrite chokes and braided wires. Any more and i lack enough length, and it simply doesn't fit.
Capacitors had no effect.

Right now i have chokes and braided wires.. Still getting to much interference to make it safe to use at a range.
My goal is to use my bot in a few air ducts. So i absolutely can't have it freaking out.

It would be up to the choke mfg what the colors meant. I got some from SuperDroids for DC motors, should be useful. Even then, they didn't have specs.

The robot chassis is aluminum, right? use it as a ground at one point for the (-) power to the motors. Tie the braid to the chassis, one end only.

Any more then that, and I'd need some really close-up, well illuminated pictures to get a better idea of your setup, and what to suggest.

Sometimes you can make up a "probe" of turns connected to a shielded cable into an audio amp.

Yeah, eliminating noise in mixed systems is more of an art then a science!

Glad you mentioned the ferrite chokes, I'd forgotten about them.

Alan KM6VV

It might be worth reading up on the operation of ferrite chokes, and see if something similar can be made using heavy iron based wire from the local hardware store.

I have plenty of chokes no need to make any.
I have about 5 now, and i could salvage another 5 or so.

The chokes don't have any markings on them.
The problem with my chokes are, to really get good effectiveness i need to wrap the wires through them like 10 times.
I was barely able to get 3 wraps in it. And if i use shielded wire, it would drop even more, to 1 or 2.

But i read 1.2ghz and even 2.4ghz can cause the same problems if the transmitter is powerful enough.
They make chokes specifically for RF interference, but i'm not sure how to use them, since they are inline, so do i use 3? or just 1 for the signal wire? i got no clue.

The wire gauge on my servos are a bit large, i could probably use a higher gauge wire without to much problem.
I'll see if i can find some high gauge shielded wire spools later. I may have to order some
I was thinking 28 awg. If anyone knows where i can get some triple strand shielded 28 or 30awg wire spools, it would be helpful.
I'll try google'ing it, but i'm not exactly sure what to search for.

KM6VV I don't know about the illumination, but heres some 6MP pictures of my bot near a $20 bill and a quarter. For size comparisons.
You can measure a twenty and get a good idea about the size of my bot.

You can see the size of the chokes in the pictures, though one is surrounded by electrical tape on the underside of the bot.



It really is a smaller robot as far as tracked bots go. It's very compact, I wanted to put as much functionality into the smallest size bot i could.

I can see that you've done a lot of work! admirable!

What I think I saw was a proto board with components, but no bypss caps. You might add some (3 or 4) .1 caps and also a few .001 caps on it's power rails.

Looking forward to seeing the video!

Alan KM6VV

Ya the caps didn't seem to do much if anything.
Maybe multiple caps in parallel would work, but i'm gonna hold off on soldering. the smoke and fumes aren't helping me any.
Got a nasty cough still.


I'm going to redo part of the arm, add 2 more beefy MG90 2kg/cm micro/mini servos in place of those esky ones. The website i used has them in stock again.
I had a dozen hitek ones but a buddy bought them all from me for $100, kinda wish i kept a couple. (i paid $15 ish)

I'm also going to replace the base rotate servo with a 360* full turn servo, a sailboat wench servo or what ever it is.
Still need an enclosure, and a couple servo controlled containers. will use servos to open and close a couple 1" wide, 2" long" 1"high containers.
So i can take "samples" with the bot, grab a sample and place it in the container. My own little mars rover.

still need to put LED's and a laser on it and the camera of course.
The LED's will be the lighting for the camera, and the laser to help aim with the gripper remotely.

Also need an spi programmer to reprogram that bluetooth uart adapter, or buy an adapter that accepts serial commands for reprogramming.
it's fixed at 9600baud.. i want at lease 38.4k So i can input more advance commands quickly enough. Then i can reprogram the whole bot.

I bought some Lasers from Interia Labs.

http://www.inertialabs.com/

Probably not on their website, but they're in the Surveyor 'bot that they sell. Email them if you're interested. And I think I previously mentioned the driver circuit that Surveyor uses.

The idea is to distribute the caps. You can also parallel up .001 caps with the .1 caps, helps with the RF. Keep the leads short!

Alan KM6VV

I already have a laser module, atm i'm just trying to find 3-wire shielded 28-30awg wire. I doubt those servos need higher awg wire.
Going to use transistor switches to turn the lasers and LED's on and off.

The ferrite cores helped the most of anything i tried, but ferrite cores + shielded wire should do the trick.
Finding a position to put the camera now is a challenge. It's just so large compared to the arm. But i'm thinking of a separate pan/tilt setup that extends over the right track and sits off to the side. Need to dig out my extra icecream sticks.


I also need some smaller breadboards, that one i have just takes up to much space.

Use some of the smaller plated-through 8029 Circbord from DigiKey V2025-ND. This is 2" x 3". Use point-to-point wiring.

I just did a tilt/pan for my Blackfin camera and WiFi board using angled C bracket and universal bracket. Two servos. Had to make a little adapter board to mate the holes in the angled C bracket to the boards of the Blackfin camera stack.

30 gauge wire is a little small for the servos. I'd have to measure, but maybe 24 would be better. Have you tried to thread servo wires through the shield stripped off of RG-58) cable (or RG-8U)? If you can't get the cable readily, I can do a test for you.

The surplus network XCVR cable I picked up has a nice shield, and 15 conductors. Probably too much for your small 'bot.

Alan KM6VV

I think 24 gauge is to large, it might even be bigger than what i currently have, that's speaker wire right?
28 gauge should be good though.

The i don't have trouble creating stuff on the cheap, but theres a limit to what i can make myself.
Pantilt is no problem, the shielded wire is.
I need really fine shielded wire.

I'm always on a tight budget, usually about $20 every month or two.
So if i can get shielded 28awg three wire lines for a couple dollars, that's what i'll do. else any more expensive stuff will have to wait.

Anyone have any websites that have these for under $3, with free shipping. Color not important, the blue matches my bot though, but really not important. Or if anyone has one they don't need pm me. I like free.

I'm trying to budget all my new parts, but the shipping is getting to me. 1/2 my budget keeps going to shipping.

Edit:
I also need these in 4x3, or 1x3 or 1x4. or 2x4 AND 1x4 or 2x3... you get the idea.

I want to make a raiser Shield for the Bot board 2.
The shield will be a 2"x3" prototype board, with these coming through, so i have workable pins coming through, so i can work right over the BB2
I'll need to bend or reduce my BB2's regulators heatsink, i don't need it that big anymore.

With this i can place the breadboard and everything OVER the BB2/BAP28, which will allow for a lot more room for other stuff.
It's going to be expensive for me to DIY it probably, but it should pay off.
Maybe i'll be able to clean up my bot too, it is a bit messy looking.
Going to take it's servo/motor power regulator, drill a hole in the body of the bot, chip away some of the paint/powder coat, then attach the regulator to the main body, use the body as a heatsink.
Then have all the wires for the regulator discretely under the BB2.

Then i'll move the arm off to the side once i get a 360* full turn servo (not continuous).
And my bot will look a whole lot better.


Edit2:
I just realized for the pin raisers, i only need 1x4's, and 1x1's/1x2's.
Then i can just use cheap header pins for the ground/power lines, just only have to solder a bridge between the 1x1's or 1x2's.
1x2's will look better, but two 1x1's will work. just finding them will be tricky. If you guys have any leads, it would work.

Robot Dude if you read this, maybe if you guys have blank, botboard 2 PCB's. Could make making a raiser easier.
Then if you like the outcome you can mass produce them.

Can i use pins 16-19 for servos? Where are they linked to? How would i use them?

I know the normal pins are P0 - P15, but i need the extra 4 pins.
I plan on making a 3DOF quadruped. (Naturally with ice cream/craft sticks)
And i want to put my robots arm on it too.

Or 3DOF hexapod.

It's going to be made with micro servos. These
I hope they are strong enough. They are definitely cheap enough.

I may make my own DIY botboard based on the Basic Atom Nano 28 or 40. It's footprint should be much smaller than the BB2.

Still need the breadboard, i'll see if i can find a place with cheap or free shipping on on.


Or I could make a DIY board with a 1" proto board, and the nano 18, and then use the nano 18 for the arm.
I could send the bluetooth command to both micro controllers, have the BAP28 ignore it, and the nano 18 use it.