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General RC Heli Discussion Discuss general topics on rotary wing aircraft, including construction, Servo's, Gryo's and Stabilizer discussions. |
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05-28-2009, 07:54 PM | #21 |
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I am: Cedric V.
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Re: Transmitter Lipo
You might have got hold of a packet of Schottky diodes that only have a forward drop of 0,25 to 0,4 volts; like the ones you would have put across a brushed motor. Germanium diodes also have a drop of that order but you are extremely unlikely to find a Ge diode other than tiny 'small signal' diodes these days.
Even if the Tx was drawing only a very few milliamps, you would likely get a drop greater than than that. Grab a pack from 'The (Chinese!) Source', once R/Shack. Any 1N400x - something, is good but there are other ones with different numbers, also suitable. Basically, a higher current rated diode will drop a little bit less at the same current. (0,55V as opposed to 0,65V say.) |
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05-28-2009, 08:34 PM | #22 |
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Re: Transmitter Lipo
I used the 1n4001 from The Source. They dropped the voltage by .9V each, and they are rectifier diodes. Be sure to solder them properly . Silver band is towards your battery connection.
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05-28-2009, 08:37 PM | #23 |
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Re: Transmitter Lipo
They are 1n4001's and they are soldered correctly. I double checked. It's a 1.4 volt drop in the radio but only .4 on the multimeter.
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05-29-2009, 04:34 PM | #25 |
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Re: Transmitter Lipo
Charged up my battery last night and now i get 11 volts at the Tx. works great now i don't have to partially charge the battery anymore..LOL
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06-03-2009, 06:20 AM | #26 | |
RCC Apprentice
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Re: Transmitter Lipo
Quote:
The diode is not fully biased (develops its voltage) until you draw a few milliamps through it. Once you turn on your TX, you are drawing ~200mA and see the correct drop. I only add 1 diode to mine and have been using a 3S 2620mAh in my 2 Futaba 7C's for months now. The extra life is great. And B-T-W, a li-po monitor is highly recommended. NiCd and NiMh might recover if you leave the TX on overnight, but a Li-Po will not. I learned this the hard way when I found one left turned "ON" in my TX box 2 days later. (gremlins I guess, lol) I now have a 5 oz papwerweight because it was drained down to zero. Marc
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06-03-2009, 08:09 AM | #27 |
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Re: Transmitter Lipo
I was kind of assumeing that, but it's good to know now. I would rather risk losing a liPo then haveing the radio shut down well flying. I too have left it on well a nicad was in there many years ago. haven't done that in a long time.
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06-03-2009, 07:26 PM | #28 |
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Re: Transmitter Lipo
The diodes, regulators etc. aren't necessary for the futaba 2.4 7c or the dx7.
I've run both for over two years on straight 3s lipo voltage. No issues at all. |
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06-03-2009, 07:52 PM | #29 |
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Re: Transmitter Lipo
You might want to read this post.
http://www.rcgroups.com/forums/showp...postcount=4539 altough it may work for now you may run into problems later.
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06-03-2009, 08:04 PM | #30 | |
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Re: Transmitter Lipo
Quote:
The amount of time the lipo stays above 12 volts isn't long, maybe one flight, before dropping into the 11 volt range. Regardless, the radio is extremely unlikely to fail from an extra .6 volts, the hardware used for voltage regulation generally has at least a 30% margin built into it. Where people are having problems is when they discharge the lipo completely and dump the onboard backup supply. That's easy enough, just turn your radio off when you're done with it ! Regards, Nathan |
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