[NSRCA-discussion] Jim Oddino or others...

Thu Apr 19 10:36:38 AKDT 2007

Troy, that's all correct.  However, in my experience these cars don't 
have a problem with the RX resetting due to battery voltage drops under 
acceleration.  However, they do have problems with the lap counting 
transponder failing to transmit when the vehicle crosses the counting 
line, so the computer system misses the lap.  The transponders are 
poorly designed, but they have a proprietary monopoly, so patches like 
these come out.  These missed laps have a lot to do with the ESC's BEC.  
A properly designed one won't require this radio power cap, but they 
aren't all well designed.

If you are getting the impression that overall quality in R/C car stuff 
is marginal, you are on to something true.  Unfortunately, despite being 
marginally designed, it's also seriously overpriced.

-Adam, getting excited about three days of racing this weekend (it's 
usually one)

Troy A. Newman wrote:
> In some of small cars as it refers to 4 cell cars when they gun it the 
> voltage can drop significantly under the load.
>
> So this cap acts to help provide power to the Radio gear during these 
> instant power peaks and valleys. If the voltage on the radio gear drops out 
> then the RX has to reset when it comes back on.  Since the way Spektrum 
> technology works and the TX and RX are "talking but not really" It could 
> take a few seconds for the RX to get back in sync with the TX....The result 
> is the model is out of control for those few moments. This is not a good 
> idea and the RC car will likely hit the wall...or a better solution is that 
> the RX goes to a HOLD condition. Not a Failsafe so much from interference 
> but a Failsafe induced by no signal "handshake" type of while its trying to 
> determine who its daddy is.
>
> See the Spektrum and all 2.4gig stuff must be bound to the TX. This means 
> the two are mated up and only listen to that digital signature. Its a who's 
> your daddy type of thing. When the RX and TX first come on at power up the 
> TX takes some time to find its broadcast frequencies,a nd the RX is sitting 
> waiting to hear the call as to where to look. If you power off the RX 
> momentarily and then power it back on there will be a lag as the RX is 
> looking for its daddy. This process takes a little more time than the 72meg 
> stuff. On the 72 meg stuff once the RX components are powered up, then they 
> see a signal and take it. There is no thought process of who the daddy is 
> and what to do...if the signal is formatted properly, and makes it through 
> the filtering and windowing process of the RX then it goes to the RX.
>
> The 2.4g stuff is not like that. Its a digital signal. like a little email. 
> The RX has to open the email and determine if its spam or not. If its not 
> spam and has the right digital signature then it processes the signal. But 
> if its the 2.4g router that is running your neighbors home network, or 
> cordless phone it won't have the Daddy signature and the RX will continue to 
> look for the right one.
>
> The Capacitor helps to prevent the power level from dropping on the RX so it 
> doesn't have to reset.
>
> This in my opinion is probably not a solution for airplanes as its not a 
> backup power source. Its a power buffer or storage device for when the 
> battery is going to see a big load. On our models there should never be a 
> time where the load is so high that the RX drops out. A stalled servo, 
> maybe...but the capacitor is only going to work for a split second. When it 
> releases its energy its done. Its needs to be recharged...and in our case 
> since the RX bat has already failed or near failure it now is trying to 
> recharge the cap as well as run the servos.
>
>
> This is very layman's description but I hate electricity. I had to take 
> electric circuit theory twice. This was the only class in college I had to 
> repeat and I still hate it today. But I can say this...I think I learned it 
> better the second time through. Perhaps I was very motivated, my USAF 
> scholarship was on the line, and a D didn't make the Col happy.
>
>
> Troy
> ----- Original Message ----- 
> From: "Michael Ramsey" <michaelr at modelaircraft.org>
> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> Sent: Thursday, April 19, 2007 9:23 AM
> Subject: Re: [NSRCA-discussion] Jim Oddino or others...
>
>
>   
>> The description refers to 1/12th scale cars. I believe the capacitor is
>> there to store energy after the power pack is depleted and allow the
>> driver to at least steer the car. I assume it replaces a separate RX
>> power source like a 4.8V battery. I don't think it has aircraft
>> applications but I could be wrong.
>>
>> -----Original Message-----
>> From: nsrca-discussion-bounces at lists.nsrca.org
>> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John
>> Konneker
>> Sent: Thursday, April 19, 2007 12:19 PM
>> To: nsrca-discussion at lists.nsrca.org
>> Subject: Re: [NSRCA-discussion] Jim Oddino or others...
>>
>> but what is it and how does it work?
>>
>>
>>     
>>> From: "Michael Ramsey" <michaelr at modelaircraft.org>
>>> Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>>> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>> Subject: Re: [NSRCA-discussion] Jim Oddino or others...
>>> Date: Thu, 19 Apr 2007 12:16:33 -0400
>>>
>>> I think its for cars.
>>>
>>> -----Original Message-----
>>> From: nsrca-discussion-bounces at lists.nsrca.org
>>> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John
>>> Konneker
>>> Sent: Thursday, April 19, 2007 12:13 PM
>>> To: nsrca-discussion at lists.nsrca.org
>>> Subject: [NSRCA-discussion] Jim Oddino or others...
>>>
>>> Jim,
>>> Can you identify and explain this component?
>>> Is it some kind of capacitor?
>>> How would it protect against low battery voltage?
>>> http://www.horizonhobby.com/Products/Default.aspx?ProdID=SPM1600
>>> Thanks!
>>> JLK
>>>
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