Pre-cocked Gearbox Shenanigans

[Docv400]

Nope.

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...An N-channel mosfet is a normally-open switch and a P-channel mosfet is a normally-closed switch.

When you apply power to the gate pin the mosfet changes state.

In a simple two-transistor mosfet all that's happening is the P-channel mosfet goes open-circuit when power is applied, thus allowing the motor to spin.

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To create a truly ACTIVE braking system you'd either need a circuit which includes a capacitor and resistor (and possibly even a third transistor) or a fancy computerised system.

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Ah, I see, that makes sense now!

I stand corrected.

 

I've never really though too deeply about how an AB MOSFET set-up did what was claimed, I just accepted it , probably because I don't think they're neccessary .

 

So basically, the ('alleged') Active Braking setups with just the 'P' channel 'FET added, are really just Passive Braking units, done electronically instead of mechanically.

 

I'm sure those that claim they are 'Active' will argue the toss over the defenition(s) of the word

 

Edit; Actually, your mentioning Capacitors jogged my memory way back to when I was first looking into this whole Braking thing.

The schematic for the Extreme Fire SW-AB-Long-TR unit does include a Capacitor, along with several extra resistors and a Shottky Diode, so maybe they do have 'true' AB?

It seemed to me at the time to be a whole lot more complexity than I wanted (or needed) to get into, which is why I never did .

I still feel it's a solution looking for a problem.

Maybe on an AEG with some insane ROF, and relatively low FPS, you might need it to prevent overspin, or possibly with the subject of this topic, pre-cocking (which I've just realised we've strayed away from quite a bit...sorry Chef ).

[Stealthbomber]

I'm sure those that claim they are 'Active' will argue the toss over the defenition(s) of the word

Well, I suppose there's a case that the back-EMF induced by the motor as it spins and is then stopped by the shorted terminals through the P-fet could be considered to be a "reverse current".

Which is obviously BS since the same could equally be said about the mechanical process of shorting the terminals via a system such as that on the G&G L85 or Marui PSG1 which're labelled "passive braking".

 

As I've previously said somewhere, the origins of active braking is in the r/c world where you could program your transmitter to tell the servo to apply reverse for a split-second whenever you move the stick from "forward" to "stop".

In normal use the car would simply coast to a halt whereas with the active braking the car will stop on the proverbial dime.

 

Course, in an r/c car this is all done with clever software in the transmitter rather than with electrical components.

[skag187]

As I've previously said somewhere, the origins of active braking is in the r/c world where you could program your transmitter to tell the servo to apply reverse for a split-second whenever you move the stick from "forward" to "stop".

In normal use the car would simply coast to a halt whereas with the active braking the car will stop on the proverbial dime.

 

Course, in an r/c car this is all done with clever software in the transmitter rather than with electrical components.

 

which is where the Lion comes in

it handles all of the "clever software" the pre-cocking, as well as the burst-fire, and does it without adding sensors unless you really want to, then there are the aux pins on the Lion

 

watching the video, you fire 5 shots in semi, the computer reads the time it takes to complete each cycle, averages them, then on the 6th shot adds an additional say 75% of the spin time and bamm pre-cocking, it has enough programming space to allow for a "suitcase"-load of modes and features, all accessible at start-up with trigger pulls, for what it looks like its going to cost, it does a lot

[tome]

Timing based burst it probably better suited to use with a lipo anyway. The voltage curve of lipos is much flatter than that of nimh so the rate as which the gearbox cycles changes less as the battery goes from full to empty in the case of lipo than in the case of nimh.

[gzus11]

thats a fair read.

 

i would also have to suggest precocking would be a pain, stock wiring at 11.1v,

got me a real nice trigger response, fast as i need it ti feel any way. (stock wiring and gearbox)

 

braking mosfet, and nice wires got rps up to 24. still with great trigger response.

 

i also feel as stealth does, manufacturers misleading customer through lack of understanding(rebranding/copy/)

or intentional lies to sell the gear. i also think that a mosfet switch is good nomenclature,

but any braking should not be called a mosfet, but a motor controller instead.

 

another side note, the ab long mosfet thing is over complicated, no reverse pulse on

breaking. from what i can understand from the circuit, the extra components supply

a better(clean/steady maybe constant voltage) signal to the gate. possibly as the chips

back then didnt have the same specs they do now