Need Advice On Receiver For T-rex 450xl

[byhsu]

Hi I want to get a Futaba 7chp radio for the 450xl cde helicopter. What receiver should I get? want something on a budget. Does it need to be a 7 channel? the radio is a 7 channel radio.

Thank You.

[Danimal]

Hi byhsu
You don't have to use a 7 channel RX with that radio a 6 will work. The Hitec Electron 6 is a good choice for your 450.
http://www.helidirect.com/product_in...roducts_id=429

If you haven't got your TX yet check out Servo City. You can get the hole system (Radio, Receiver, Servos, Crystals) all in one package for a really good price and save your self some money that way instead of buying everything one at a time.
http://www.servocity.com/html/transm..._packages.html

[byhsu]

Danimal:

What radio do you recommend? I want something with subtrims. I heard is useful for centering the servos, something that the Futaba 6EXH doesn't have.

So I can use the Futaba 7chp, which is a 7 channel and use a Hitec 6ch receiver then? The 7CHP is the lowest priced radio that has the subtrims feature. for Servos I am looking at the Tower Pro SG90, 3 for the cyclic and 1 Tower Pro SG50 for the rudder. Gyro is the GY401.

I have heard some people using a digital servo for the tail, what exactly is the difference between an analog servo? any benefits?

Thank You.

[byhsu]

Originally Posted by Danimal

If you haven't got your TX yet check out Servo City. You can get the hole system (Radio, Receiver, Servos, Crystals) all in one package for a really good price and save your self some money that way instead of buying everything one at a time.
http://www.servocity.com/html/transm..._packages.html

If I want to use the Optic 6, can I use the Elctron 6 receiver with it? is it positive or negative shift?

Thanks for the link, they have good prices.

[hawkman]

You dont need a digital servo for the tail.....they are quite expensive and will eat a bit more battery power.

Computer type radios offer subtrim...and 'end point' which means you can control the servos range of travel...(strain those servos and you will have trouble).....I would say go for a complete package like 'Danimal' said....I would be careful of using receivers that might not be compatible with the radio you are using....getting that complete package should give you peace of mind.

Rob

[byhsu]

Hawkman:

Do all computer radios offer subtrim? I was under the impression that the Futaba 6EXH doesn't. I was really considering that radio, since I could fint it at $170, including receiver, and 4 micro servos and free shipping.

[Danimal]

byhsu
I will try to answer your question about servos with some help from a friend I am still trying to digest all this info.

The two main components of a servo are a motor and a variable potentiometer (pot).

Mechanically, they're connected though a set of gears. The pot's resistance is used to determine the current position of the mechanics. The position information is used to drive the motor in one direction or another to move the mechanics to the desired position determined by the receiver/transmitter or gyro in the case of the tail servo.

The positioning logic is generally referred to as a "feedback loop." The current position is compared against the desired position and either a positive or negative voltage is applied to the motor to move it in the correct direction.

Hope all of this makes sense so far ...

Now .. this logic can driven by a "static" analog feedback circuit or through a digital "dynamic" programmable signal processor. Both methods accomplish pretty much the same effect ... moving the mechanics in one direction or another by comparing its current position from the pot to the desired position signaled by an outside source.

The advantages of the digital approach are #1 - the logic can be much more complex, therefore, more precise ... in theory at least, #2 the logic can be changed dynamically ... programmed, and #3 manufacturers need only a single logic circuit for all of their product, each product with its own operating parameters. Things like speed vs torque, velocity, etc. can be programmed in ... and changed dynamically.

The disadvantages of digital are primarily, price and power consumption. Typically, a digital version of a servo will consume more battery than the analog equivalent ... although on the newer servos, I'm not sure this is entirely true ... since the newer digital only servo's motor/pot tend not to have an analog equivalent.

Hope this helps ...

[byhsu]

Danimal:

Thanks, this explains it to me and Now I know I can just put a analog servo for the tail.