Chronic Glitching Trouble!!!

[Sean Patterson]

I have a CRC Carpet Knife and can't seem to keep the thing from glitching and sending me in the wall. I'm running 4cell with a Noval GT7 speedo, XXL AM receiver, Futaba 9602 high speed servo, monster pro stock motor. All my connections are hardwired(if that affect glitching). I have tried every trick in the book. I have trid all different kinds of placement with my receiver and nothing. I even put it up on its side. All the motors I ran yesterday had fresh trued comms and new brushes. I noticed when I picked my car up after one run yesterday that I got a little shock from the chassis. Do cars pick up enough static electricity while running on carpet to cause glitching? Any advice would help cause I'm at a loss here!!!

[Piggy89373]

Sean, it's quite easy for static to build up when running on carpet. I don't think it's likely that it's causing glitching. Static build-up would usually end up with catastrophic results as opposed to causing mild glitching.

Here's some tips to reduce the amount of RF noise your equipment will generate.

Wiring:
Most people overlook wiring and string it everywhere, or coil it up. When wire is coiled and has voltage put through it, it takes on special properties because it's become an inductor. Inductors are the crudest forms of materials used to create RF energy. Instead of coiling up your excess wire, create folds that do not coil.

Battery wires are commonly overlooked. When creating your battery packs or putting on your deans connectors, twist the wires together first and put some flexible shrink tubing over them to hold them in place. You'll create what's called a twisted pair, it helps reduce the magnetic field created from voltage going through the wires.

Also, minimize the contact of wires on cf, graphite and aluminum. The more distance between the wires and cf/graphite/aluminum/metal the better off you are.

Capacitors:
The primary purpose of capacitors are to bleed off the electrical surges from a rotating armature. Rotating armatures create AM RF energy. Good quality caps as recommended by your the motor manufacturer installed correctly will greatly reduce the amount of RF noise created by your motor.

Speed Controllers:
ESC's by nature will always create RF energy. There's no way to get around this. There are some things you can do to minimize this effect. Using aluminum foil, create a pocket around your ESC to make an RF shield. Be careful doing this, you need to ensure constant airflow in and around the ESC for cooling. You also don't want the foil to come into contact with any of the electrical connections. You can glue the foil to pieces of scrap lexan so it'll retain it's shape longer and protect it against roll-overs, crashes, etc. Make sure that part of this foil is held in place tight to the chassis. Best case scenario, depending on your car's layout when possible, is to tie in the foil so that it's held in place by your motor mount. This grounds the foil. If it's not possible to do this, just make sure the foil is held in place firmly.

Metal to Metal Contact:
Do your absolute best to reduce the amount of vibration from metal to metal contacts. Tighten up all the screws to prevent any static from jumping from metal to metal and creating RF noise. It sounds goofy, but it's a common occurence.

Carbon Fiber:
Carbon fiber can cause some RF energy to be routed in and around your receiver. When possible, minimize contact between the receiver and cf as well as cf and your esc. If necessary, use two pieces of servo tape atop one another to add a bit of distance.

Antenna:
Antennas are a specific length to provide optimum transmission and reception. Make sure your antenna wire is in tact, has no nicks, cuts, abrasions, etc. If it does, the cheapest fix is to use heat shrink tubing. The best solution is to replace the wire. When routing the wire, route it as far as possible from your ESC, motor, wiring, and cf. Also, minimize the distance from the antenna straw and your receiver. The closer the two are, the better reception you'll get and the least amount of glitching you'll get.

Receiver:
Your receiver is your key component here. More often than not, receivers being too close to RF noise generating components are the culprit for glitching. Keep your receiver as far from your esc, motor, servos, cf, etc. You've done a decent job of it so far, so find that sweet spot. You can also take some aluminum foil again and wrap the sides and bottom of your receiver to help shield it. A few dabs of Shoe Goo will hold it in place. Make sure that all corners are completely covered.

Servos:
Servos are audibly noisy and rf noisy. Reduce this by wrapping your servo in aluminum foil and/or keeping your receiver and antenna away from it. Always keep your servo in good working order. If you're still getting glitching, connect a different servo to your car and see if it's still glitching. Although unlikely, it's still a possibility well worth exploring.

When all else fails, look at replacing your receiver. With use and time, electrical components wear and begin to fail. Some of this is design flaw, some is from using cheap parts.

If you intend to replace your radio and receiver, there's a number of manufacturers out there. If you wanted to stay in the 27 MHz AM band, take a look around and make an informed decision. See which radio is having the best success. You might want to change to FM, but that's not a guaranteed fix to glitching. Once again, do the research and make an informed decision.

I hope this helps out. If it does, please post back and let us know which trick(s) worked.

[Sean Patterson]

Thanks, your advice helped. I found the problem. I had installed lower standoffs on my car and that allowed for my battery bars to touch a piece of cf. So I put some electrical tape across the back of my cells and problem solved! Thanks! Man I wish that when I was first in to rc racing back in the late 80's early 90's that we had the internet! What a great tool!!!

[Piggy89373]

Glad to know it worked out for you. I've been wondering what the cause of your problem was, now we know. Guess that's something else I need to file away for later considerations, non-shrink wrapped batteries.

I agree with you, having a forum like this to share problems and come up with solutions is the absolute bomb! I, like you, relied on what little track knowledge people would be willing to share. Back then, most would grumble and hide their stuff to protect their "secrets."