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Old 06-12-2019, 07:22 PM   #621
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

OK,let's talk about this, why on earth do you want to power the servo externally? The receiver will power the servo very nicely if you merely supply it with clean juice. Give it garbage (any BEC on the planet) and it's another story. I have 27 emails (and counting) with a fellow who wants to use stock type electronics despite my practically begging him to treat it like a nitro truck and isolate control-electronics from propulsion-electronics. How? Very, very simple. Use a 2S 1000 LiPo with dual leads. What does dual leads gain you? 10A into the receiver for starters! Best of all, that 10A is TOTALLY unaffected by anything the propulsion motor and electronics do. Think of it as a battery supplying pure analog juice versus synthetically derived digital juice (via FETs). Just like tube amps are better for mission critical stuff versus digital amps, analog juice from a battery is mo betta. Bottom line? There's just no need - in my opinion - to go outside the servo to do it. Please explain because maybe I'm having a stupid moment. Convince me!
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Old 06-12-2019, 07:37 PM   #622
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

All they were suggesting was to have a JST lead coming off the servo used to power it, in addition to the servo lead. JST lead would then get plugged into the battery leads and share the battery voltage.

On the other front of garbage signals with crawlers a clean signal vs a garbage signal is indiscernible, I find your servos work just fine off of garbage signals.

Last edited by HumboldtEF; 06-12-2019 at 07:40 PM.
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Old 06-12-2019, 07:40 PM   #623
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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Originally Posted by jbeech View Post
Give it garbage (any BEC on the planet) and it's another story.

I agree BECs are garbage.
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Old 06-12-2019, 08:15 PM   #624
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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OK,let's talk about this, why on earth do you want to power the servo externally? The receiver will power the servo very nicely if you merely supply it with clean juice. Give it garbage (any BEC on the planet) and it's another story. I have 27 emails (and counting) with a fellow who wants to use stock type electronics despite my practically begging him to treat it like a nitro truck and isolate control-electronics from propulsion-electronics. How? Very, very simple. Use a 2S 1000 LiPo with dual leads. What does dual leads gain you? 10A into the receiver for starters! Best of all, that 10A is TOTALLY unaffected by anything the propulsion motor and electronics do. Think of it as a battery supplying pure analog juice versus synthetically derived digital juice (via FETs). Just like tube amps are better for mission critical stuff versus digital amps, analog juice from a battery is mo betta. Bottom line? There's just no need - in my opinion - to go outside the servo to do it. Please explain because maybe I'm having a stupid moment. Convince me!


I’m stupid but the rx gets its power from a built in bec( limited amps usually) that will brown out under loads. Holmes has a 500 inoz servo that has a jst to power direct off your main 3or4s battery. You preach no bec, so hang a jst lead on for the masses.


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Old 06-12-2019, 08:25 PM   #625
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

If you watch propulsion pack voltage when you load and unload the pack using the motor that drives the truck (e.g. the propulsion motor exercising the propulsion battery pack) you'll be 'astonished' at how low the pack voltage will go.

So riddle me this, why on Earth would you want to have your control electronics, e.g. the servos and receiver, subjected to the huge variability in both torque and speed that results from the propulsion pack supplying voltage that's all over the map? Seems nuts to me. And what's the point? After all, control is all about control so stable voltage is the design goal and hooking up to an unsteady voltage source seems self-defeating.

Like I said, I don't get it but if this were smart then everybody would be doing it, e.g. Futaba, MKS, SAVOX, Jeti, Hitec, Airtronics, KO, everybody (us included). If they ain't, I'm suspect - if for no other reason than they aren't rushing to do it. First rule of merchandising, "copy better things as quickly as possible". So who else is copying this? And if the answer is nobody, then ask yourself, why not?

Dont you get it? When you accelerate the truck, the pack voltage drops. A lot! This means the servo will have less torque and speed the whole time you're accelerating. And you actually want this? I'm confused. I mean we can make the electronics run off 11.1 or 14.4V, we don't care, won't cost much. But EVERY single time you goose the throttle, the voltage drops waaaaay down. During that period of time, the servos won't have as much torque or speed as they're rated for. Is this a joke? Am I misunderstanding? You actually want to have a variable voltage feeding your servos? Why?

Last edited by jbeech; 06-12-2019 at 08:35 PM.
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Old 06-12-2019, 08:31 PM   #626
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

John Rob Holmes to the white Courtesy phone please!!!!!


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Old 06-12-2019, 08:34 PM   #627
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

He's got a point... No mainstream manufacturer does it.
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Old 06-12-2019, 08:40 PM   #628
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

You don't need me to tell you this, an idiot can figure it out. Hook up a WATT meter in the line with the pack and motor. Goose the throttle. On the bench is good enough but with the load of the truck (8-10lbs) it'll be a LOT MORE PRONOUNCED and observe pack voltage. It drops like CRAZY! And when you ease off the throttle there's a back EMF pulse spike you can't see with the WATT meter that'll blow your mind. I really can't conceive of a single reason to want to operate your control electronics with variable voltage off the propulsion motor's battery pack. None. But, I have an open mind. Convince me, I'm game.

Watt Meter - genuine item - but knockoffs can be had for $15.
https://www.amazon.com/RC-Electronic.../dp/B001B6N2WK

Last edited by jbeech; 06-12-2019 at 08:43 PM.
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Old 06-12-2019, 08:45 PM   #629
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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He's got a point... No mainstream manufacturer does it.


And makes damn good servos, I tend to listen carefully.


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Old 06-12-2019, 08:47 PM   #630
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

The thing is with crawlers we rarely goose the throttle let alone steer at the very same moment. You apply logic from other RC avenues that have very little to do with conditions we typically see in crawling.

I appreciate the conversation BTW
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Old 06-12-2019, 10:01 PM   #631
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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Originally Posted by HumboldtEF View Post
The thing is with crawlers we rarely goose the throttle let alone steer at the very same moment. You apply logic from other RC avenues that have very little to do with conditions we typically see in crawling.

I appreciate the conversation BTW


Bingo. In a comp situation or even in a trail run the throttle rarely goes 100% and if it does it is momentarily. If anyone was wanting to run a separate power lead for a servo on a boat I can fully see the apprehension since they see full amp draw for a longer period of time. That just isnt the case with crawlers. Gotta step out of your airplane bubble to see the big picture.
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Old 06-12-2019, 10:25 PM   #632
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

OK, strap a WATT meter to your rig temporary like and go for a crawl. See what the voltage did. And airplane bubble or not, we still come back to the central question, why on Earth do you want a variable voltage supply for your controls? Don't you understand that means variable output from the servo - any servo. What's the fetish of using one pack instead of isolating the pack for control from the pack used for propulsion? A battery costs like $15-20 bucks and supplies the best juice money can buy. Or buy a BEC for more than that and it supplies garbage. I mean I grok why you use a BEC with a toy truck and a child because responsibility for managing two packs may be a bit much, but you guys are men and you definitely aren't running toy trucks. BECs exist for one reason, saving the manufacturer money. They have zero to do with performance. Zip. And variable voltage is nuts for every conceivable reason. It means your servo reacts differently as voltage changes. Why would you desire this? I really, really am perplexed why you'd want inferior performance after spending a lot for superior capability. It's like taking a world class sprinter and forcing him to run whilst carrying a 100lb sack of corn when competing with others not encumbered, e.g. handicapping him. Variable voltage handicaps the servo. Any servo, not just mine. But I remain with an open mind for a performance reason for doing this. What is the reason, having to do with performance, for wanting to operate your controls off a variable voltage source? I mean we bust a nut trying to extract the most possible performance from all the components and package them into our servo and some of you are basically telling me performance isn't important? Now I am really confused. Have you ever looked at the specs chart for our servos. We publish torque and speed for several voltages ranging from 4.8 through 8.4VDC and they mimic that of any other servo on the market. Less voltage means reduced torque output and increased transit time - weaker and slower . . . and this is a good thing?!? Note; this is true for every single servo on the planet. So when the propulsion pack voltage varies, the amount of torque you have available from your servo varies - and - the steering response is slower. Just for a moment imagine driving to work where your cars has less power steering sometimes and more power steering at other times. You'd take it to the dealer to have it repaired! Or perhaps driving it when the brakes are easy to operate sometimes and very hard to operate at other times. This would make for a very difficult car to operate. Same thing with these rigs when the voltage to the servos is varying based on the demand being placed on the battery pack by the propulsion motor. Reflect back on how throttle is applied to your rig. Is it a smooth application of power, or are you on and off the throttle constantly as you find a line and work your way up or down the course? Every time you vary throttle, not to 100% just varying it a little bit means the voltage is varying. Yet we design controls for the most steady source possible so that you get a consistent result. I keep seeking analogies. Imagine riding a bicycle with rubber handle bars so that as you apply torque to steer the bars bend and thus, you can't ever predict what the front wheels will do. That's in effect what some of you are saying you want, variable results.

Last edited by jbeech; 06-12-2019 at 10:48 PM.
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Old 06-12-2019, 10:40 PM   #633
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

Regardless of your apprehension we would welcome this product with open arms. The whole 'on paper' engineer way of thinking may not apply to our application.

Theres also weight savings reasons we dont want extra batteries.

What you refer to as inferior performance, I cant feel I honestly feel no difference what so ever.

Crawlers are a different beast, they are just different!

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Old 06-12-2019, 11:14 PM   #634
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

Where am I going to put another battery pack on this rig? And if I manage to finagle one in there somehow just how much is the overall performance going to suffer at the behest of some minor performance gain through using a separate pack to power the servo?


This ain't an airplane, airplane things don't work in this world.

That's a 500 man 4s pack with the red tag, go ahead and let me know where a 1000mah 2s is going to fit.

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Old 06-13-2019, 05:23 AM   #635
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

to jbeech:

Wouldn't a separate JST lead off the servo help accomplish what you're saying, isolating the power from propulsion while also allowing the servo to run off its own battery? I understand what you said about sending the power to the receiver, but what about receivers that can't tolerate higher voltage? I'm still running the RTR receivers in a couple of my rigs and I'm limited to 6V. A JST lead directly on the servo would allow me to connect to an a 2S pack without the voltage limitation imposed by the receiver.

Last edited by Boiler; 06-13-2019 at 10:26 AM. Reason: spelling
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Old 06-13-2019, 09:41 AM   #636
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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Where am I going to put another battery pack on this rig? And if I manage to finagle one in there somehow just how much is the overall performance going to suffer at the behest of some minor performance gain through using a separate pack to power the servo?


This ain't an airplane, airplane things don't work in this world.

That's a 500 man 4s pack with the red tag, go ahead and let me know where a 1000mah 2s is going to fit.



It looks like there is plenty of room on the roof
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Old 06-13-2019, 11:27 AM   #637
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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It looks like there is plenty of room on the roof
Yup, all the heavy stuff should go up as high as possible for optimum performance.
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Old 06-13-2019, 02:03 PM   #638
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

As big as that pic is, it looks like you could mount a 12v deep cycle car battery just about anywhere!😮

I kid of course. 😝

Trying to get engineers to understand real world applications can be frustrating.
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Old 06-13-2019, 06:41 PM   #639
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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Yup, all the heavy stuff should go up as high as possible for optimum performance.


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Old 06-13-2019, 06:42 PM   #640
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Default Re: ProModeler Servo: 420oz, billet case, o-ringed, $79

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As big as that pic is, it looks like you could mount a 12v deep cycle car battery just about anywhere!



I kid of course.



Trying to get engineers to understand real world applications can be frustrating.


I am an engineer whose job is to get engineers to understand real world applications.
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