Extra Servo wire?

[Click]

Hi,

Purchased a used Tamiya M03, need to change the ESC to a standard Tamiya unit (club rules!)

Everything is fine apart from one extra cable. There is a single cable coming from the existing ESC (not Tamiya) to the servo?

There is the usual 3 core cable coming from the servo to the receiver BUT there is this extra single cable from the servo to the ESC anybody know what this is for?

Depending on the answer I get is there anyway of using this cable with the standard Tamiya ESC (TEU-101BK)


Thanks in advance

[ashleyb4]

It sounds like a 7.2v fet wire is it blue? If so you can connect it to the (+) of the battery. Do you know what servo it is???

A

[JohnM]

Sounds like the "fet" wire to power the servo, pretty normal a few years back.

[AlisdairO]

It's probably a FET wire. In which case, you can attach it to the positive wire of the battery, BUT you need to stick a servo choke between the battery and the servo, or you could damage your servo. You can get them for about £1.50 from DMS.

[Click]

It sounds like a 7.2v fet wire is it blue? If so you can connect it to the (+) of the battery. Do you know what servo it is???

A

Hi Lads,

Thanks for the replies, never had any dealings with FET servo's before.

The wire is Blue so give that man a prize:thumbsup:

Can I take a feed from the Batt connector on the receiver? or do I take a feed from the positive battery wire from the ESC?

Will the servo still work if I don't connect this blue wire?

Sorry if this is really basic 101 RC stuff but as I said I've never used a FET servo before :lol:


Many Thanks

[Ferret]

You need to take a feed from the positive battery wire.

[Click]

Hi,


Thanks for all the info./advice.

I now know what to do :thumbsup:

Click

[Beanie]

Sorry to ressurect this one, got myself a PDS-2123FET to use on the B4 for steering, as per Click then i've never come across one of these FET servo's before either?!

So do I need to solder a FET servo choke inline on the blue wire and then connect this to the positive coming out of the battery directly? I notice it says 7.2V also, but I'm running a 2 cell lipo so technically it will run from 8.4 down to 6.0 volts? Will this be ok, obviously the battery is classed as 7.4 nominal, but will it be ok?

[super__dan]

I run 2123's with a direct feed from the battery without issue using lipos

[Beanie]

Do i definitely need a FET Servo Choke thing? If I'm using 2.4ghz radio does that make a difference and if I take the power feed for it direct from the positive battery wire?

Or do you have to have a Choke regardless?

[super__dan]

Why not run one? They cost about £1

[Southwell]

You could get interference if you dont run the choke.

[Beanie]

Oh sure, happy to run one and cost is not a problem, it's just that I don't have one and I wanted to run the servo tomorrow night. Will it not work without the blue wire connected to the power source? Will it damage the servo if I run it without a choke? Less likely to get interference as I'm using 2.4ghz?

[discostu]

no it wont damage the servo the choke is used to balance the positive fet feed to the servo basicly remove any voltage spikes etc.

the servo will not work if the blue wire comming out the servo isn't connected to either the batt+ or the blue wire coming out the esc (you may not have one from the esc).

stu

[Beanie]

Anyone know what the size/spec. of a Servo choke is, surely from the look of it then it's simply a resistor that could be obtained from Maplins or similar for pennies?

[bodgit]

This may be it
http://www.maplin.co.uk/Search.aspx?criteria=fet%20chokes&source=15
the online is out of stock but you may get lucky at your local store.

[Beanie]

Any idea which size choke i need from that page?

2.2
4.7
10.0
22
47
100
470uh?
1mh?

[bodgit]

Sorry forgot to put that in you need the 4.7uH


http://cgi.ebay.co.uk/10-x-4-7uH-Inductor-RF-Choke-Inductors-4-7-uH_W0QQitemZ260450728600QQcmdZViewItemQQptZUK_BOI_ Electrical_Components_Supplies_ET?hash=item3ca412b a98
Its also handy to use heat shrink over it as it is such a small wire/fet solder joint