[NSRCA-discussion] berg 7 channel Rx

[Ed Alt]

Basically, the way our standard servos work is that they trigger a one shot 
on every pulse received.  The output of the one shot is a pulse of opposite 
polarity to the input pulse whose width is controlled by the feedback pot 
position  (corresponds to the servo arm position).  These two pulses are 
summed and if any error signal exists (if they don't match exactly in pulse 
width), the error signal is stretched (made wider) and amplified to drive 
the motor in one direction or the other to resolve the error signal.

The electronics are "dumb" in a standard servo and within certain timing 
limits, you should be able to increase the effective output torque by 
increasing the sampling rate of the pulses that are fed to it.  I don't know 
that it would be exactly double, but it should go up.  This is because the 
motor is not driven at 100% duty cycle when it's running, i.e., it receives 
a train of stretched pulses, but not a pure DC voltage level.

Ed


>From: "Fred Huber" <fhhuber at clearwire.com>
>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] berg 7 channel Rx
>Date: Wed, 13 Sep 2006 22:16:11 -0500
>
>Max output torque of a servo is a function of battery supplied voltage, the 
>motor in the servo and the gear ratio.
>
>Changing the signal line frequency will not alter the servo output torque.
>
>Also.. max torque of a servo can sometimes be a GEAR TRAIN limit.  
>otherwise it would be impossible to strip a sevo gear in flight.  No change 
>to the voltage supplied is going to alter the strength of the gears in the 
>servo.
>
>It may effectively increase the servo resolution and thus sensitivity to 
>being off center, but it will not increase its available torque.
>
>It MAY have the servo circuit apply more power at a smaller deviation from 
>"demanded" position...  But that is an effect of resolution.
>
>So.. it may apply full torque available at half the deviation from demanded 
>position... (may be what you MEANT to say...)
>
>Note that using a dual-inverter "glitch buster" 
>http://www.uoguelph.ca/~antoon/gadgets/noiserx.htm (especially with Futabe 
>127 DF RX's) will boost the signal line from the RX output (appx 3.8 v for 
>the Futaba 127 when using 4.8 v NiCd pack) to full RX pack voltage.  This 
>can increase effective resolution. (especially with long servo leads)
>The circuit is INTENDED to filter interference from long leads... and it 
>works.  The side effect is almost as good as the intended purpose.
>
>  If you can find the chip to make the circuit... I'm having trouble 
>finding the DIP (.10 inch pin spacing) I got some .05 in pin spacing 
>chips... which are going to be harder than heck to solder into the circuit, 
>but should do the job.
>   ----- Original Message -----
>   From: Scott Pavlock
>   To: NSRCA Mailing List
>   Sent: Wednesday, September 13, 2006 4:59 PM
>   Subject: Re: [NSRCA-discussion] berg 7 channel Rx
>
>
>   {trimmed}
>   The nice part about this is it gives the ability of any analog servo to 
>output twice its normal torque.
>   {trimmed}
>
>   Scott Pavlock
>
>
>   On 9/13/06, White, Chris <chris at ssd.fsi.com> wrote:
>     Hi Mike Mueller,
>
>     Oops…I meant to imply "They seem to be okay in low cost electrics"J   
>I'm not ready to try a $50 receiver in a big-buck R/C application either…
>
>     Chris
>
>
>
>
>----------------------------------------------------------------------------
>
>     From: nsrca-discussion-bounces at lists.nsrca.org 
>[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of mike mueller
>     Sent: Wednesday, September 13, 2006 1:44 PM
>     To: NSRCA Mailing List
>     Subject: Re: [NSRCA-discussion] berg 7 channel Rx
>
>
>
>      I know that Castle took a long time to introduce them to the market. 
>The initial designs that they had right after taking over Berg were not up 
>to the standards they wanted. I'm really impressed with these and can't 
>wait to try one. I'll also test them in a small IC plane before having 
>confidence in a pattern plane. The people at Castle are top notch. It's 
>also good to see an electronic component actually made here in the US. Mike
>
>     "White, Chris" <chris at ssd.fsi.com> wrote:
>
>     Hi Mike,
>     I know some foamie guys are using these and treat them like they are a
>     standard.....They should be okay.
>     Chris
>
>     -----Original Message-----
>     From: nsrca-discussion-bounces at lists.nsrca.org
>     [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Michael
>     Wickizer
>     Sent: Wednesday, September 13, 2006 12:24 PM
>     To: nsrca-discussion at lists.nsrca.org
>     Subject: [NSRCA-discussion] berg 7 channel Rx
>
>     Anybody have experience with these receivers? At only 8 grams, sure
>     would
>     be a weight savings in electric applications.
>
>     http://www.castlecreations.com/products/berg_7-channel.html
>
>     Mike
>
>
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