Dropping 1 volt?
 

I'm looking to get a pro modeler 470 for my wraith. I have a mamba x and I want to run the BEC at 8.4v. The problem is my airtronics 371wr will only go up to 7.6v. Could I just put a small resistor in line to drop 1 volt? I run 3s batteries. Thanks for the advice.

Sent from my SM-N920V using Tapatalk

Re: Dropping 1 volt?
 

Doesn't really work like that. Your resulting V would depend on the current (load). You could use a Zener diode, methinks.
Or a string of regular rectifier diodes (a la 1N400x) but the voltage drop would vary a bit.

Maybe best to get a separate small cheapo BEC @6V. :)

Re: Dropping 1 volt?
 

Just get the Holmes hobbies bypass and your good

Sent from my SAMSUNG-SM-G935A using Tapatalk

Re: Dropping 1 volt?
 

bypass? what would I be bypassing? please explain.

Dropping 1 volt?
 

Power direct to servo, internal bec only powers rx
https://uploads.tapatalk-cdn.com/201...03ba940608.jpg
You still need an external bec though


Hang up and Drive

Re: Dropping 1 volt?
 

So I cant just set mamba x BEC to 8.4V and bypass power wire directly to the servo? This is the first RX I have had that can not handle 8.4V. The BEC will then also supply 8.4V to power the RX on a seperate lead to the servo. Maybe I will use my rx462 or rx471. They can supposedly handle the 8.4V from the mamba x BEC. Again I am not running the power to the servo through the RX. I just want to prevent using another device on my toy.

Re: Dropping 1 volt?
 

that is a nice little harness. Keeps things clean and plug and play. Me likey. Now if I can hit the RX with 8.4V to save my Castle external BEC for a rainy day."thumbsup"

Re: Dropping 1 volt?
 

While the full 470 oz of torque is wonderful, 440 at 7.4V is plenty and requires little more than setting the Mamba X's BEC and plugging it in.

Re: Dropping 1 volt?
 

The load in this case should be very stable and mostly unchanging. The only thing being powered in this case is the RX. It will only be providing signal to the ESC and the Servo. A diode is a great idea, why did I not think of that? simple .7v drop per diode.

Re: Dropping 1 volt?
 

True, my Wraith needed all 470 as I run soft foams up front


Hang up and Drive

Re: Dropping 1 volt?
 

Bypass means 3s direct to servo, no?

Re: Dropping 1 volt?
 

You need to power all servos and the receiver.

You can power everything from the external BEC or the Internal ESC BEC. This means 1 voltage to all servos and receiver. In this case you'd get whatever the BEC is set to. This might be fine for your Steering Servo, but small servos or winches might have issues with that - as might some receivers.

A Bypass will power one (or more depending on the bypass) item at the External BEC settings. So lets say you have a HV servo capable of 8.4v but your receiver or other servos only handle 6v. The bypass would be wired to send the BEC's 8.4v to the HV servo only and the remaining items could be powered by the ESC's internal BEC.

Re: Dropping 1 volt?
 

not in this case. I would be bypassing the RX from the BEC built into the ESC."thumbsup"

Re: Dropping 1 volt?
 

Yes, rectifier diode will be good for you. Just look at definition of it and you will have your voltage drop

Re: Dropping 1 volt?
 

you could also use a cheap hobbywing ubec to drop down to 6v

Re: Dropping 1 volt?
 

Yes, but you need power for the receiver now. If you string 2-3 1n4001 diodes in series on the 8.4v power wire from ESC to receiver it should drop it 1.3-2.7v. A typical 1n4000 series drops 0.65v at zero load and 0.9v at 1 amp, roughly. The receiver shouldn't use much power nor will it spike, so voltage won't fluctuate much. They aren't rated above 1A continuous FYI.

You could also get a really cheap hobbywing BEC clone that gets power from either battery or MMP BEC power and drop that to a safe 5-6v for just the receiver. Both solutions above feed MMP BEC 8.4v direct to the servo.

Re: Dropping 1 volt?
 

First, mamba x will only go up to 8.0v. Didn't know that. Next, my rx seems to be ok with 8.0v. Now my problem is I need a servo for my dig unit. Finding a cheap servo to do this that can handle the 8.0v is tough. Thinking about a small 2s 350ma battery to handle this workload. I know John recommends only using a battery and to always forgo the BEC of any sorts. The battery will be a much cleaner power source. I should have just put an shv500 on it. Direct to 3s and I could have set my BEC to any voltage.

Sent from my SM-N920V using Tapatalk