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Archive for February, 2012
Posted by Ribble | Feb 23, 2012 @ 02:25 AM | 3,398 Views
Motor Amps using battery MAH rating and flying time
Calculate motor amps from flying time

Motor amps ?
If you start with a full battery and get an accurate time how long the battery lasts, you can figure out the average current that the motor drew during those minutes.

Amps = (mah) x (1amp/1000ma) x (60minutes/1Hour) / (RunMinutes)
Amps = (mah) x (60/1000) / RunMinutes
Amps = 0.06 x mah/minutes

Example: Amps = 0.06 x mah / Minutes
Amps = 0.06 x 1000 / 6 = 10 amps average current
Amps = 0.06 x 1000 / 3 = 20 amps average current = 1000mah battery that lasts 3 minutes
Amps = 0.06 x 1300 / 3 = 26 amps average current
Amps = 0.06 x 1300 / 4 = 19.5 amps average current
Amps = 0.06 x 1300 / 5 = 15.6 amps average current
Amps = 0.06 x 1300 / 6 = 13 amps average current
Amps = 0.06 x 2000 / 6 = 20 amps average current = 2000mah battery that lasts 6 minutes
Amps = 0.06 x 2000 / 3 = 40 amps average current
Amps = 0.06 x 680 / 6 = 6.8 amps average current
Amps = 0.06 x 680 / 3 = 13.6amps average current
Amps = 0.06 x 900 / 6 = 9 amps average current
Amps = 0.06 x 900 / 3 = 18 amps average current

Well, more or less. Pick a ratio of MAIN/TAIL and apportion the total amps
A good ratio may be 3/1 where main = 75% and tail gets 25%
Posted by Ribble | Feb 23, 2012 @ 01:28 AM | 3,964 Views
TRANSMITTER POWER SETTING
EU limits output power to 100mW
US limits output power to 200mW = 200mW output power 2.4GHz RF

0dbm = 1mW
3dbm = 2mW
6dbm = 4mW
10dbm = 10mW
20dbm = 100mW
23dbm = 200mW

A Simple yet effective RF Sniffer
http://macgregor.co.uk/support/faq/gen-2.htm

2.4GHz Antenna 1/4 wavelength = 30.7mm = 1.21 inches
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DH9104 & DH9100 TX schematic drawing (actually transmits 4 channels)
http://www.rcgroups.com/forums/showthread.php?t=1571121