Flawed IR Design Confirmed
 

OK, after frying the 5V regulator on our IR board twice, I think I can safely say that the IR board has a flawed design. Although, I know how I fried it the second time. It was because I accidentally reversed the polarity of the input voltage. Apparently the 5V regulators do not take reversed voltage very well. :D

If FIRST decides to use such boards in the future, I would REALLY recommend that they design it with a diode. That way the diode would restrict the current to only go one way.

I have also fixed our board twice. This time, I even had the exact L805 laying around on an old board of something else.

Well, that's all the info I have. I hope this helps clear some things up.

Re: Flawed IR Design Confirmed
 

While the device may not be robustly designed, the user neglecting to properly check connections before applying power is hardly a design flaw. All of engineering is about trade offs, and the designers of this board traded simplicity of design, lower production cost, and the ability to accept a wider input voltage for a need of greater diligence on the part of the user.

In any case take this as a lesson to check your work... improperly wiring the IR board may cost you a dollar and a few minutes, but mproperly wiring the RC may cost you $450 and your team's capacity to develop software for this year's competition.

~Phil

Re: Flawed IR Design Confirmed
 

So you connect the board with the polarity wrong and they have a flawed design? I'd say it was pilot error.

Diodes restrict current flow to one direction, not voltage.

Re: Flawed IR Design Confirmed
 

Did i say voltage? oops. I meant current.


...And yes, I think it is a flawed design.


I don't mind replacing 5V regulators. It helps my troubleshooting skills.

..and yes, it is my fault for connecting it wrong, but a better design would help.

Re: Flawed IR Design Confirmed
 

Thanks for the warning, I'll be sure to tell our programmers about the potential problem.

I definitely agree with you that any reverse voltage sensitive component should be built with a diode too. It's not like it requires much extra engineering.

Re: Flawed IR Design Confirmed
 

The diode/current statement was correct. You are asking that a diode be placed at the voltage input terminals such that a reversal would cause the diode to be reverse biased and no current would flow. The downside of this kind of design is that the diode drops 0.6 volts when forward biased. In a robot when the drive system demands a lot of current, the battery voltage does fall and that extra 0.6 volts may make the difference between working and not working.

Re: Flawed IR Design Confirmed
 

That is definitely a possibility. But, as long as you keep that in mind when designing your robot, then I don't think it would be much of a problem.

Re: Flawed IR Design Confirmed
 

so replacing the 5v regulator will fix it if we accidently reversed polarity? I mean, we realized we only reversed it for a split second and now it doesnt work during our first connection....didnt think that a connection of under 2 seconds would break it, but whatever

Re: Flawed IR Design Confirmed
 

Electricity can travel pretty fast in 2 sec ;p. Before you go out and buy another board, try replacing the regulator. It should fix it. If it doesn't, then you'll have to buy another one. :/

Our team has only hooked the IR board once and thankfully we got the polarity right. :P

Re: Flawed IR Design Confirmed
 

the fragile nature of this board is very disappointing. i do believe that it was not intended for robot mounting. but, it was adapted to the task. it makes no sense to run the board on 12 volts when the 5 volt line is readily available on the RC.

jerry w

Re: Flawed IR Design Confirmed
 

ummmm...i know its an odd time to ask this but how do u hook the board to a powersource we split the black and white wire and directly connected it to a 6 pack AA battery set......the wires got extremely hot and the tip started to burn

please help on this issue:confused:

Re: Flawed IR Design Confirmed
 

That would be because the black and white wires (the first two) go to the same place on the board - the voltage input. You were essentially shorting out your batteries. Try connecting the black wire to the positive battery terminal and the grey one (the third wire) to the negative battery terminal.

Re: Flawed IR Design Confirmed
 

If I add a diode to the IR board, will it prevent it from breaking in case the polarity is accidentally reversed? If so, where should I add it?

Re: Flawed IR Design Confirmed
 

Team Fusion had their first try with the IR board mounted on the robot this evening with bad results. Here are the problems we encountered:

• With the programming, the digital input must be 1 in order to count it as pressed (this is bad because if one of the cables comes loose, it will result in a robot without any sense of where it is going)
• Very gittery unless you run the motors for about 10 loops, then the robot drives for a few hundredths of a second before it stops.
• The board will fry itself after a few minutes.

Yes, that's right, we fried our board, and I can't figure out what is wrong with it. The 5V regulator is putting out exactly 5 volts, the wires feeding the IR board are wired properly and working, and it WAS working perfectly.

We're not sure what happened, but while driving it, it all of a sudden took off on its own, hit our unwelded frame against a concrete wall. My first thought was it was a dead backup battery, and this was indeed true, so I replaced the battery with one reading about 7.8 volts, and it did the same thing, smacked into the wall. So I declared that we had problems and started to investigate, and yet, I found nothing wrong. I think we have it on video too of it going spastic on its own.

I definitely think there is a flaw in the design, a very dangerous flaw as the robot will all of a sudden start running on its own. Another flaw, if one of your wires comes loose, it will drive on its own. I'm going to contact FIRST and see what their conclusion is.

Re: Flawed IR Design Confirmed
 

Ok i may be over stepping my boundaries here, but I noticed the other day that when we tried to use our IR board that it too was fried, when i say this, i mean it turns on but it goes right to the first input and stays there, well i dont know that actaully because we havent hooked it up to anything but the light stays on and wont change, so is this what happens when its fried?