Ant Weight

Hey everyone, I figured I might as well make a build diary to ask you all a load more questions and sap you bandwidth with pics :D

If you saw my other post you'll know I have the base of an old rc Tiger tank and have dismantled it in an attempt at making an ant weight.

I've been fiddling with it a bit, now it just needs the electronic parts to make it go... on which note... I still have no idea where to find a suitable controller, since a large number of robots just have a skid steer configuration, what controllers do you guys use? Thanks

and I will upload pics when it decides to work for me....

My robots tend to use either Peter Waller's custom controllers or Sozbots ones, but a good starter option (as I might have suggested earlier) is the Sabertooth 2x5A for RC - http://www.active-robots.com/products/m ... ails.shtml - I used one of these in my first ant with no problems. (it then went on a bit of a journey and presently resides in Andy Jackson's antweight :P)

That will give you skid steering with an option to either drive it tank style or have the control signals mixed so you can control it with one stick on the transmitter.

Dammit, yeah I know what speed controller to use, sorry I mean transmitter... (it's a controller to us less educated folk)

I have the speed controller and receiver on order, should be here shortly, which means the bot will be done shortly apart from means of controlling it...

What reciever have you bought? Then we can tell you what transmitters it's compatible with, hence, which to buy

Futaba 40MHz micro rc

an as promised, pics of my bodge job :)

http://i617.photobucket.com/albums/t...y/CIMG0425.jpg

http://i617.photobucket.com/albums/t...y/CIMG0424.jpg

http://i617.photobucket.com/albums/t...y/CIMG0426.jpg

http://i617.photobucket.com/albums/t...y/CIMG0423.jpg

Update:

I'm made a decision to scrap this and build a bot from scratch instead, not sure what kind of design yet but it'll still just be a simple pushbot type

aaaaand... does anybody here actually know anything about transmitters I keep asking but...
Help would be appreciated on the subject :wink:

that's a bit general. To save me writing an essay on the subject do you have a specific question or two about them in mind?

Yes, where is a good place to get one? do they come as part of the controller (that's the controller you hold) or do you have to find that separately? I'm after a 40MHz one preferably with skid steer style controls 8)

Generally the transmitter and the controller you hold are the same thing :)

Okeydoke, thanks for the replies ;)

One more noob question... Could you use a transmitter built for 2.4GHz or other frequency and put a 40MHz crystal in it? Would it work or not...?

And since this is a build diary: I've nearly completed the robot, after buying a few parts and scavenging bits of plastic etc, I'm not sure yet whether to have a wedge or shovel or otherwise on the front yet :wink:

Short answer - No

Long answer - 2.4ghz and 40 mhz refer to the frequency that the transmitter works on. 2.4ghz sets don't use crystals to change frequency. Instead, there are a set number of channels within the 2.4ghz band (around 20ish if i remember right). The transmitter just finds one that is free and uses that. The receiver knows which transmitter to take direction from as they will have previously been bound to one another (different sets and manufacturers have different methods for doing this)

If you want to use 40Mhz you will require crystals etc and will expect a fair bit more potential problems with interference although with an antweight this probably won't be a problem due to the distances involved. Also make sure if you are using a dual conversion receiver, you use dual conversion crystals.

Excellent, thank you,

and as always knowing the answers raises more questions, (pretend I'm testing you :P )
I have a receiver already which is this one:
http://www.technobotsonline.com/futaba- ... -4-ch.html
Which is single conversion.
I'm having trouble finding the right transmitter (apparently 40MHz is going out of fashion) but there are a few, would this transmitter work with the right crystals? I'm assuming it will:
http://www.alwayshobbies.com/Boats/Radi ... -40Mhz.ice
I know it's a trans/receiver set but it's cheap... :roll:
Also, searching around some more raises another question, What's the difference between AM and FM? Is it just frequency? (and quality of radio station...)
:?: :?: :?:

AM or amplitude modulation is the easier one to do and often used in cheap rc toys
It's downside is that it is easily affected by electical noise and will often get crowded out by other radios or your motors

FM or frequency modulation is better as it is less prone to noise but it still can happen.
http://images.autoanything.com/image...Modulation.gif

Considering that you can buy a 2.4GHz transmitter and reciever for the same price or lower it might be worth a change
http://www.elitemodelsonline.co.uk/P...=googleproduct
http://www.giantcod.co.uk/gianitcod-...-p-403779.html

Technically it should work with the futaba receiver but I wouldn't bother. Generally with radio gear it is best to stick to the same manufacturer for your receiver and transmitter. The transmitter will work with the receiver it comes with. My honest opinion is to sell the 40meg receiver and buy a cheap 2.4ghz set for 25 to 30 quid. From what others have said about these sets, they should do the business.

If you are determined to go for 40meg then I have an old skysports 6 (http://www.instructionsmanuals.com/mode ... ontrol.htm) transmitter that I may be willing to part with. Let me know if you are interested.

AM - Amplitude modulation
FM - Frequency modulation

Each differs by the way in which the signal sent from the transmitter. If you imagine the signal being sent as a sine wave then AM changes the amplitude or height of the wave whereas FM changes the period for a single wave to be emitted. However as far as we are concerned with robots, AM is crap for interference, FM is what you want to use if you are going to use 40 meg.

if you want a weapon you'll need atleast a 3 channel. if you want to stick with 40 mhz i suggest :
http://www.sussex-model-centre.co.uk/sh ... p?id=19142

£20 for 3 chn transmitter and receiver.

if you decide on 2.4ghz this is one of the cheapest sets:
http://www.giantcod.co.uk/gianitcod-24g ... 03779.html

i have one its actually quite good :)

Just when I thought I nearly had everything done :lol:

From what I understand 40MHz is being phased out in favour of 2.4Ghz so annoyingly it's probably the way to go.

AM/FM = P/S waves gotcha, but I suppose that's irrelevant with 2.4GHz...

Quote:

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if you decide on 2.4ghz this is one of the cheapest sets:
http://www.giantcod.co.uk/gianitcod-24g ... 03779.html

i have one its actually quite good

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Awesome, since this is for an Ant though do you know the approximate dimensions and weight of the receiver?

Thanks for the help, much appreciated :wink:

it weighs 12 grams or 6 without the casing nnot sure of size though

Quote:

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Originally Posted by harry hills

it weighs 12 grams or 6 without the casing nnot sure of size though

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Ok thanks, it seems like a reasonable substitute then :)

Just thought you may like to know, Peter Waller (of Combatant fame) has developed an antweight speed controller that fits directly onto the Radio link receiver, soldered directly together, Heres a few pics:

http://i109.photobucket.com/albums/n...6/CIMG0939.jpg

http://i109.photobucket.com/albums/n...6/CIMG0942.jpg
Compared with the actual receiver (the RX/Speedo unit is lighter than the original receiver :)

http://i109.photobucket.com/albums/n...6/CIMG0947.jpg
Intalled in a bot

Those 4 pins sticking out are for a weapon servo, which can be run off full battery voltage or 5v regulated (hence the markings on the unit)

You can find pete's e-mail on the the Robot Wars 101 Forum

That Rx / ESC is such a neat design/idea.

I like that.