Failsafe if transmitter signal fails.

[Paul75Participant @paul75]

Hello Everyone.

My model of HMS Duke of York is controlled by an old 7 channel Digifleet XP/FM Tx / Rx system. Whilst I was bench testing the model the transmitter battery went flat resulting in the problem of the motors running at full speed until I switched the boat's power off. I understand this is quite a common problem but is obviously something I wouldn't want to happen when using the boat on a pond.

I've referred to the Digifleet operating instructions manual but cannot find any instructions regarding setting the system with a failsafe receiver throttle off condition if transmitter signal is lost.

Does anyone have know how I might include this failsafe into the Digifleet Tx / Rx system or can I bolt on additional radio kit to achieve the same result?

Many thanks,

Paul.

[Paul75Participant @paul75]

[Dave MilbournParticipant @davemilbourn48782]

Paul

Most current electronic speed controllers (ESC) have a failsafe built into their circuits so that the motors will stop if a signal is lost (e.g. ACTion, MTroniks, Electronize, Microgyros). If you replace your present ESC then do take note of the wiring into the plugs. Fleet had a negative centre pin while everyone else used centre positive.
The most obvious solution is to make sure that the batteries are charged up the night before you go sailing. You might also replace low-capacity NiCad cells in the transmitter with higher-capacity NiMH ones. You can use the same charger but pro-rata the charging time e.g. if your old pack was 700mAH and the new one is 2100 mAH then charge for three times the duration. A pack of this size will give you more than a full day's sailing on one charge. Again, check the positive and negative wiring on the Tx battery pack; I ca't remember if Fleet also had a plug and socket in the power lead from the pack to the PCB/switch. Component Shop are the best suppliers of battery packs I know of **LINK**

Dave M

[Malcolm FraryParticipant @malcolmfrary95515]

What type of ESCs? Normally they just do as the RX tells them, and, as Dave said, no signal, no output. In turn, the RX can only do what it thinks the TX has told it, no signal in, no signal out. Did the problem just happen with the TX on a low battery, when all bets are off regarding signal integrity, or with it actually switched off?

There are modern sets that I have heard of that are intended for air use which have extra cleverness built in such that a loss of signal turns the motor off ie stick fully back, when in a boat this is a disaster, because stick fully back is full reverse. But that is not likely in this case.

[Dave_PParticipant @dave_p]

I stand to be corrected but I think there is an electronic device that can be added to the RX that will return esc to off on loss of signal. I will do some deleving as I cannot remember were I have seen the info.

 

Sorry, I was thinking of a unit for I.C. powered models so no use here.

Dave

 

Edited By Dave_P on 21/09/2013 13:18:10

[Dave MilbournParticipant @davemilbourn48782]

There are plenty if you just Google "Radio Control Failsafe". Quite whether or not they're any good and/or compatible with Fleet gear is another thing entirely.
Keeping the battery charged is a cheaper and safer alternative. If it won't hold a charge then it will need replacing in any event.
Suit yourselves.

Dave M

[Paul75Participant @paul75]

Thanks for your replies.

I think in the first instance I'll follow Dave's advice and closely monitor the transmitter battery charge and replace the pack, if required. The two ESCs (one for each pair of motors) are Electronize Type 43HX items which, like the RC kit, are old tech. The loss of signal occurred when the Tx battery went flat when bench testing and, if memory serves, the motors went into full reverse.

Thanks again,

Paul.

[Malcolm FraryParticipant @malcolmfrary95515]

Electronise units of a certain age were inclined to see a lack of signal as a very short pulse, i.e. full reverse. They also tended to go "vroom" at switch-on as the capacitor holding the reference voltage woke up. Modern types with a little computer on board do not suffer from this.

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