How small a Tx can we make (or need)?

[Wayne_H]

Spotted this today:
https://blog.hackster.io/atto-is-or-wil ... 673df5ee15

Makes me wonder how small a Tx we can make, irrespective of whether we really need it miniscule or not I can see merit in a pen sized (& shaped) s/c Tx. The push button would be in the top, twist the top to turn it on/off, and return it to your shirt pocket when not in use. Of course, it must also be a working pen so that you can sign autographs

Batteries could be a set of button cells, but what to do with the "gigantic" RF boards we have at the moment? Add a laser pointer and a sonic screw driver & we have a device any Smart Doctor would covet, would you believe...

[Phil_G]

This unanswered question has been niggling at me until I just had to give in and have a go

So how small can a useful homebrew R/C transmitter be?





It has all the facilities too, reversing, minute-minder, inactivity alarm, mixers including the S/C mix, etc... but not wired! and its FHSS of course the 'stick' is a proportional 2-axis unit from a PSP or whatever,
it has poor centring so its programmed with a narrow 'dead band' at neutral. The on/off switch is one segment of a DIPswitch. You've probably guessed whats inside!

[PaulJ]

Brilliant Phil! ...... Can we see the insides? Where is the antenna?

Paul

[Phil_G]

It uses a proportional micro-stick unit, used I think some pocket games. It doesnt centre that well so is programmed with a narrow 'deadband' which is not noticable in use but gives accurate centring:

Inside its quite cramped, most of the 'stick' is inside the case and next to it is a 100mAh lipo cell.
Mounted in the other case half is of course (you guessed!) a Keywish RF-Nano:

The case is made from half a Poundland LED pocket radio/torch, the two-AAA's battery-holder part:

Also available on ebay: https://www.ebay.co.uk/itm/Repair-Repla ... 2944559289

The stick does look more like a button but it is actually proportional and runs the same FHSS code so is compatible with all the other stuff Not yet flown - but I will, with the ease of swapping in-flight it would be rude not to...
[Edit: Flown (briefly!) in the Lidl glider at Baildon!]

[Martin]

Very neat!

Maybe try a tiny accelerometer board, or just the chip, instead of the 'stick' for the next one? Just tilt the whole transmitter around its x and y axes as a substitute for stick movement. You could use your deadband scheme with that too, though perhaps it might not be needed...

[PaulJ]

My god there are some clever bu***rs on this forum!

Your ingenuity seems to know no bounds.......

Paul

[tiptipflyer]

Brillant Phil,
thanks for the inspiration. I have all items at home (even the micro stick unit), so I just need to build something similar.
Cheers
Frank

[MaxZ]

Yes brilliant!
I have been intensely looking at the video and the pictures, but I cannot detect a button or buttons to operate the minute minder, s/c mixer etc.? I can detect some swift hand movements in the vid, did you use one of those gravity operated switches?

Cheers,
Max.

[MaxZ]

did you use one of those gravity operated switches?

How's that for an idea then, shake once for right, shake twice for left.........

[Mike_K]

To be honest the beer looks as interesting as the transmitter