RC Model Reviews

A few people have been converting Spektrum radios to work with the Chinese DIY modules (such as those from Assan, Corona, FrSky, Fly-Dream, etc).

With some of the Spektrum transmitters only using a 4-cell battery pack, it is difficult to meet the minimum 6V power requirements of a DIY kit like the Corona. What's needed therefore is a way of stepping the 6V up to the 9V or so that these modules need for reliable operation.

Today I found this little gem on the Himodel website:

2.5-25V Input, 3-25V Output Step-up Voltage Regulator

If it works as advertised, it could be a useful way of getting enough voltage for any DIY module that isn't happy with 6V.

Here is another one:
http://www.dimensionengineering.com/AnyVoltMicro.htm
They also have all sorts of cool stuff.

Yes, they are quite common but what struck me was the Himodel unit's 4A current capacity and its surprisingl low price (just $11.75).

This would also be an option for those wanting to run the RC gear from a single-cell Lipo, especially since it's only 6.7g. Might be good for DLG or whatever.

I looked at the spec list for the HiModel unit and it said INPUT current 4A. Do they have this wrong and mean Output current? There was nothing listed for output current capability unless they are listing it wrong.

Ah, you may be correct (doh!)

Further down the page it states that it'll do 2A @5V though, which is still pretty good.

Maybe I'll get one and test it out to see what it *really* delivers?

Nice one there Bruce, just what I was looking for to do a conversion on my Nephew's transmitter.

Might be interesting to note that it seems to be possible to run the FrSky DIY off 5v.

I am about to drop off a mail to them to verify as if I look at the DIY instructions they cut and pasted the JR/Futaba module specs which state 6-13V however further down in the intructions which are for installing the DIY module it speaks of connecting 5V.

I also know it works as I have had someone connect a BEC set to 5V powering his DIY module and Fly-Dream module both work flawlessly so far.

Will contact my contacts at FrSky and see if that is just a typo or if you have an answer for the lower powered transmitters.

Given that the internal circuitry for the transmitter modules is all 3.3V, they should run okay on 5V, so long as that's within the capabilities of the regulator.

The FrSky uses an switching-mode regulator and these generally have a lower dropout voltage (ie: the minimum allowable difference between input voltage and output voltage) so you may be right.

When I get time, I'll put a transmitter module to the test and see what the dropout voltage is.

This is one good aspect of the FrSky system versus some of the others. By using a switching regulator, they actually draw much less current than the systems which only use a linear regulator (especially if you're still running an 8-cell NiMH or 3S lipo in your transmitter. The result is that you can fly a lot longer between recharges and the module doesn't run hot like some others do.

Will post the formal response from FrSky returns my mail full of questions and suggestions. Just some small changes to make installing the DIY module even easier. Like more flexible silicon wire and slightly longer leads.

I got a long mail back from FrSky however the one line that is of importance is the following :
-- snip --
This information is from Techinical engineer:

It can work around 5V.
-- snip --