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Old Nov 29, 2012, 04:50 PM
Sherpa
Schwemmer's Avatar
La Quinta, Ca.
Joined Sep 2003
1,654 Posts
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Receiver power drain

I was reading another thread and came across a statement that I haven't thought of prior. Does the new 2.4 technology really use more power than the old 72 MHz?

here is the statement.

One thing that often catches people by surprise is that 2.4 GHz receivers typically use more power than the 72 MHz receivers they replace. For example:

Receiver R148DF
(FM Dual conversion)
Receiving frequency: 50 or 72 MHz bands
Power requirement: 4.8 - 6.0V Ni-Cd battery
Current drain: 14 mA
Size: 1 x 2.2 x .9 (25.4 x 55.8 x 22.9 mm)
Weight: 1.1 oz (31.18 g)
Channels: 8


Futaba R617FS 2.4GHz FASST 7-Channel Receiver
SPECS: Size: 1.6 x 1.1 x .35" (40 x 27 x 9mm)
Power Requirement: 4.8 - 6V
Current Drain: 80mA (at no signal), 74 mA(w/ signal no servos on 4.8)

Thanks
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Old Nov 29, 2012, 06:29 PM
Proud RC Addict
United States, UT, American Fork
Joined Nov 2009
1,560 Posts
So what if it really does draw 80mA?
That seems pretty insignificant compared to your motor don't you think?

example, suppose a typical tiny 800mAh battery powering a little park flyer. Consider 70% usable mA so 560 mAh available. at 80mA = 7 hours.

Did I do any math wrong? Seems like a non-issue. You're only going to fly it for 6-10 minutes and most of the energy goes to your motor.
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Old Nov 29, 2012, 07:38 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
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Our Nano receiver draw 15.8mA to 19.7mA (depending if the LED is on) during receive mode, and only 1mA more during the ACK transmission phase.
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Old Nov 30, 2012, 02:53 AM
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Launceston Arpt, Tasmania, Australia
Joined Jan 2004
564 Posts
Quote:
Originally Posted by mulicheng View Post
So what if it really does draw 80mA?
That seems pretty insignificant compared to your motor don't you think?

example, suppose a typical tiny 800mAh battery powering a little park flyer. Consider 70% usable mA so 560 mAh available. at 80mA = 7 hours.

Did I do any math wrong? Seems like a non-issue. You're only going to fly it for 6-10 minutes and most of the energy goes to your motor.
close! but since you use a battery, then the Voltage decreases over time and
so does the current drain. For your math to be accurate, you need a constant Voltage supply.
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Old Nov 30, 2012, 06:46 AM
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The Villages, Florida
Joined May 2003
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Dang !!

When I saw "new thread" in my email notification I thought it could be Jim D making his "big announcement" (to include news of the release of the Tx)......

That's what I get for "thinking".....
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Old Nov 30, 2012, 11:36 AM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
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Quote:
Originally Posted by E_ferret View Post
close! but since you use a battery, then the Voltage decreases over time and
so does the current drain. For your math to be accurate, you need a constant Voltage supply.
That's not true with a constant current device, like a receiver. The current consumption remains the same throughout - it's not like an electric motor where you are feeding it 100% of the voltage/current full time, so the RPMs decrease due to the lowering voltage/current. Receivers use a regulated voltage (3.3v), so as long as the input voltage from the battery is above the drop out voltage of the regulator, the current consumption will always be the same.
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Old Nov 30, 2012, 04:07 PM
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Launceston Arpt, Tasmania, Australia
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Quote:
Originally Posted by JimDrew View Post
That's not true with a constant current device, like a receiver. The current consumption remains the same throughout - it's not like an electric motor where you are feeding it 100% of the voltage/current full time, so the RPMs decrease due to the lowering voltage/current. Receivers use a regulated voltage (3.3v), so as long as the input voltage from the battery is above the drop out voltage of the regulator, the current consumption will always be the same.
I agree there.
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