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Originally Posted by Andy A.
Secondly. You mentioned that the low battery light is on. If this light is one when you are teatherd, then your RC is probably not getting enough power either. That light comes on when the RC's voltmeter drops to a certain level. This value can be changed int he program, but I think it defaults to 10 volts. Usally this doesn't cause radio problems, but I have noticed it can crop up when using a very old battery or if there is a bad connection between the RC and the battery. How is the RC being powered? Did you end up powering through the cars 12volt system? Did you ever check the quality of that power? It may not be adequate. If this is the case, then your RC radio may not be fully powered, which could result in the same symptom. Check the voltage at the RC's power terminals with a voltmeter. It should read right around 12v, give or take 2.
-Andy A.
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Our original setup:
* OI plugged into wall via 9V AC Adapter (the amperage was NOT 1500mA, i believe it was lower)
* RC hooked up to 12V battery by running 18-gauge copper wire from the battery's terminals to the contact points on the RC
* RS-422 Screamer Tx hooked up to OI via DB9 cable
* RS-422 Screamer Rx hooked up to RC via DB9 cable
* Joystick in port 1 on the OI
* RC hooked to computer for program download via DB9
When we did this, the radios both had the "standby" LED lit up and there did not seem to be any transmission. "Valid Rx" was not lit up, and the "No radio modem" led was blinking, i believe (i dont have the materials in front of me right now). In any case, the radios were not getting any sort of signal.
The transmitter's antenna IS broken (read: snapped off) about half way up. I assume this will have adverse effects on the range and reliability, but I would assume it would still be able to communicate with a receiver that is only 2 feet away and in direct line of sight. Perhaps not?
To answer a few questions:
We were originally going to power the RC through the car's battery, but when we plugged it in, it continually turned on, then shut off, then turned on, then shut off, etc. Obviously, this was unacceptable, so we are going to power it with a separate 12V battery that seems to power it well. With this set up (and using a tether) we can operate motors and the such nicely!
I am not on a team and never was on one, believe it or not. Everything I know about robots and control systems and the sort (that is, not much) I picked up in the last week. We borrowed the equipment from team 571 which is the team at our school, Team Paragon at Loomis Chaffee in Connecticut.
And, finally, an update:
We located the gas cable which, we found, was much harder to cut than expected. But, after a lot of using wire cutters and pulling (we even used pruning loppers and an electric drill!) we finally cut the resilient cable and hooked it up to our servo. We mounted the servo more-or-less securely under the hood and hooked it into the RC. Using a tether, we were able to pull the throttle cable and rev the engine by tilting the joystick forward! Very exciting! Clearly, we will not take the car out of the garage until all systems are working (and the radio problems are solved). Still, it is somehow very gratifying to rev the engine with a joystick!
ARP