Another RDT question

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Martin
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Location: Warwickshire

Re: Another RDT question

Post by Martin »

Three of these arrived from BangGood this morning.

https://www.banggood.com/2_4G-4CH-Mini- ... rehouse=CN

Super tiny, cheap, and (according to the blurb) full range. Four normal servos supported. The comments say that by shorting two channels together you can get CPPM on one channel (same as the D4R-II and presumably 8 channels worth - so good for multirotors or other aircraft that use a compatible flight controller).
You have to solder the (supplied) servo connectors yourself but this is a good thing if you're trying to save space and weight as you can omit the connectors and solder servo leads direct to the receiver.
Failsafe is only supposed to work on one channel - obviously choose that channel for throttle - this is different and inferior to normal FrSky receivers where all channels can be programmed to failsafe by a quick prod of the binding button when already powered up and receiving.
GarydNB
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Joined: 15 Feb 2018, 23:12

Re: Another RDT question

Post by GarydNB »

Thanks for the replies guys....would this work?

https://hobbyking.com/en_us/frsky-sd1-s ... toggle-tab

All it has to do is one operation of a micro servo for d/t of a free flight model.
Martin
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Location: Warwickshire

Re: Another RDT question

Post by Martin »

It looks like it should work but I've never tried one myself. If you go to the 'upload files' tab from that link you posted there is a one page manual you can download. That tells you there are multiple ways to change the channel that the decoder uses (if you should need to change that).

It seems like you can change the channel with a FrSky Servo Channel Changer (SCC) that you'd have to buy separately, or some PC software with a suitable interface, or by using a Taranis transmitter. The SCC seems the easiest way but I suppose costs the most.

If you only want to operate one micro servo, then you can most likely leave the device set up on whatever channel it ships with (channel 1 presumably) so you wouldn't need to change the decoded channel anyway.
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ozrs
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Location: West Australia

Re: Another RDT question

Post by ozrs »

Gary - this rx should drive the servos(s) directly.

https://www.banggood.com/2_4G-8CH-D8-Mi ... rehouse=CN
Richard
GarydNB
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Re: Another RDT question

Post by GarydNB »

Ok. Got one of these for radio dt. It needs to perform a single activation of a tiny servo using Phil's dt gadget. I'm using a 1S 50mAh lipo. Tx is a DIY FrSky hack module.
NOW....2 questions
1. What do I solder where? No manual available:/
2. Can I solder the lipo (via two small wires,) directly to the rx and still charge it without making smoke?
Thanks chaps,
Gary
Stew
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Re: Another RDT question

Post by Stew »

Gary, if you go here
http://www.mccrash-racing.co.uk/sc/blog.htm
and look for the blog post on 10/01/2016, there's a wiring connection diagram and some notes on the RDT

Does this help?
GarydNB
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Joined: 15 Feb 2018, 23:12

Re: Another RDT question

Post by GarydNB »

Thanks Stew, that is largely concerned with the transmitter, the tiny reciever shown has no instructions at all and I can't find a manual anywhere. The problem is where to attach the various servo wires and the battery.
Gary
Stew
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Location: Staindrop, Darlington.

Re: Another RDT question

Post by Stew »

Ah yes, I see your point. More knowledgeable people than I will hopefully chime in.
I'd certainly put a glob of hot glue or something on that aerial connector though. My last 2 crashes have been cause by loose connections in those.
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Phil_G
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Re: Another RDT question

Post by Phil_G »

Item P22 on the Archive page of www.singlechannel.co.uk Gary Image

The tranny is wired exactly like the blue picture:
rdt_tiny85.jpg
Just 3 cables to connect - module, button and battery.

At the receiver end, it depends on which receiver - if its a V8R4 or a D4-something then the plugs are oriented so all four negs are central:
v8r4_pins.jpg
The RDT works on all 4 channels, just choose the one thats most convenient:

Ch1 Normal direction, full throw
Ch2 Reversed direction, full throw
Ch3 Normal direction, half throw
Ch4 Reversed direction, half throw

The Frsky receivers are fine on 1S and you can power it from any channel on the rx.
Dont wire the cell permanently to the rx though - use a servo plug & socket or to save weight extract the pins from a servo plug & socket, but you must insulate them with heatshrink. Short=certain fire!
'Socket' to the battery, 'pins' to the rx. You only need unplug the pos to disconnect between flights.
The servo can be permanently soldered.
Binding is the usual power-on-with-button-pressed at both tx & rx ends, then a power cycle both ends.

Easy peasy!
Cheers
Phil

PS Ah, hang on, I just read the previous few posts. So its a Banggood rx? back in a mo...

rdt_rx.jpg
GarydNB
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Re: Another RDT question

Post by GarydNB »

BRILLIANT!
Thanks Phil.
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