Hi all, as mentioned previously in an Instructable I am into UAV's. Latest purchase was for an upgrade transmitter from the Devo 7 to a Futaba 10J. Require the extra channels as I want to control the camera gimbal with not only roll but also yaw. Also, I am making up retractable landing gear as I want to move the camera and batteries to a more central location on the UAV to achieve a better balance.
Presently running a Lipo 2200 mAh battery for the existing video receiver, screen and the transmitter (Devo 7). These are all located on a transmitter tray. The Lipo is a 3S putting out a little over 11 volts. The screen, receiver and existing transmitter run on 12 volts but even with 11 volts with a Lipo this is no issue. You only have to charge the battery up when you finish operations even with several hours of flying. It just lasts.
The new Futaba transmitter runs 6 volts. Some are installing a 2S battery which puts out 7.4 volts. I presently run all 3S batteries for everything and the thought of running another different size battery not at all something I wanted to do. Also most I have seen install them in the battery compartment, with a Lipo I believe has some elevated risk in doing it this way.
What to do? Easy way is to purchase a set of rechargeable batteries/charger and plug it straight in to the transmitter for about $30 or find a DC converter.
Step 1: DC to DC Converter
What current would a transmitter draw. Not a great deal I suspect though it can discharge alkaline batteries in a relative short time. But then again a good "AA" alkaline I believe has about 2700 mAh at 1.5V. Rechargeable Ni-MH batteries have about 2200 mAh at 1.2 volts. There are other types of batteries but again it is another charger and set of batteries. Why not use what you have. If we could produce something around the 1 to 1.5 amp mark at 6 volts should be more than enough and the Lipo will handle it.
Now there is a number of DC converters, I wanted something simple and something I could safely install where the batteries would normally go. Jaycar Electronics have just what I required, an adaptor module multi-voltage regulator rated up to 1.5 amps (http://www.jaycar.us/PRODUCTS/Power-Products-Electrical/Power-Conversion-%26-Transformation/DC-DC-Converters/ADPTR-MODULE-MULTI-VOLTAGE-REG-1-5A/p/AA0372). It is one of those you can put a voltage of 6 to 18v in and tap what you want out from 3 to 15 volts, I wanted 6 volts, price $6.50. Length 63mm by Diameter 24mm.
Step 2: Fitted and Operating.
Made up a cable with a connector to connect to the Lipo battery side soldered it to the Input of the regulator. Then used the original connector cable from the battery pack and soldered to the output of the regulator.
It works perfectly and the Lipo is located to the transmitter tray outside of the transmitter, this makes it easier to monitor and charge the battery away from the transmitter and I still only have 3S batteries.