Author Topic: I need help finding parts  (Read 5328 times)

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Offline kanekTopic starter

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I need help finding parts
« on: July 07, 2009, 09:17:41 PM »
I was looking around for parts to buy for a robot I plan on making. I am very new to this since I am just starting and I would like to have a suggestion or advice to begin with.

I am looking for the following parts:
1 Transmitter (preferably one with two 6 degree sticks)
1 Reciever
2 Crystals
2 Servos (ones that will get the job done, under 12 dollars each)
1 Battery and Charger

I am looking for the stuff on this list and if you know an online store that sells all of these items and combined under a total of 120 dollars, please tell me. Thanks.

Offline sonictj

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Offline Joker94

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Re: I need help finding parts
« Reply #2 on: July 08, 2009, 04:20:18 AM »
what country do you live in, that makes a big differencs. as it is a goood idea to stay as local as you can to keep a hold on shipping

by this i mean try to stay i your country

Offline kanekTopic starter

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Re: I need help finding parts
« Reply #3 on: July 11, 2009, 05:54:03 PM »
« Last Edit: July 11, 2009, 06:20:05 PM by kanek »

Offline Conscripted

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Re: I need help finding parts
« Reply #4 on: July 11, 2009, 08:43:38 PM »
What is your applicaton going to be? It will make a difference when selecting parts. The radio equipment you found is 72Mhz. According to the FCC those can only be used for aircraft and are not legal for ground use. If you are looking for a radio for ground use you will need 75Mhz.

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Offline Razor Concepts

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Re: I need help finding parts
« Reply #5 on: July 11, 2009, 08:52:46 PM »
Technically it is illegal. But it's not like the FCC will go arrest you. Just saying  :P

You can get stuff for cheap if you buy used... try ebay or rcgroups.com

Also, when you buy new radio systems, the majority of them come with a reciever and crystals, and some come with servos. If you want to check out the new stuff try. www.towerhobbies.com , amazon generally sucks for this kind of stuff.

Offline Conscripted

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Re: I need help finding parts
« Reply #6 on: July 11, 2009, 09:04:27 PM »
True, the FCC my not knock at your door. On the other hand it would really suck to show up with a combat robot ready to go and find out you can't compete because your radio doesn't comply with their rules.

Offline SmAsH

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Re: I need help finding parts
« Reply #7 on: July 11, 2009, 09:31:51 PM »
but then couldn't you just change the crystals around?
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Offline Conscripted

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Re: I need help finding parts
« Reply #8 on: July 11, 2009, 09:53:56 PM »
No not really. A 72Mhz transmitter won't work with a 75Mhz crystal and vice versa.

Offline SmAsH

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Re: I need help finding parts
« Reply #9 on: July 11, 2009, 10:43:59 PM »
No not really. A 72Mhz transmitter won't work with a 75Mhz crystal and vice versa.
oh! i used to think you could change the frequencies by switching crystals out for others?
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Offline Conscripted

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Re: I need help finding parts
« Reply #10 on: July 11, 2009, 10:51:56 PM »
You can change the frequencies. Within the same range. You can change the "channel". You chould go from using channel 11 (72.010 Mhz) to channel 30 (72.390 Mhz) or channel 60 (72.990 Mhz). You get the idea. You can't step up to the 75Mhz channels.

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Offline SmAsH

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Re: I need help finding parts
« Reply #11 on: July 11, 2009, 10:53:00 PM »
ahhh, i see. thanks for that conscripted!
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Offline kanekTopic starter

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Re: I need help finding parts
« Reply #12 on: July 12, 2009, 11:17:49 AM »
Ok so I changed my retailer to Tower Hobbies and these are the things I looked at for buying:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJA83&P=M
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJC33&P=M
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXH28275&P=7
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXARP078&P=BR

I want to make sure that my first buy will last a while so I want to make sure it is as good as it can be. By the way it will be used for ground use as a car.

Offline SmAsH

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Re: I need help finding parts
« Reply #13 on: July 12, 2009, 04:41:38 PM »
Are you sure you want a ni-cd battery? i would say ni-mh is much better in terms of lasting longer as it doesn't get the memory effect and can normally hold more mah to its weight.

The charger is all good for that battery...

For the transmitter, are you sure you don't want to go for a 3 channel? just encase you ever want to expand with a light or something? i take it you are using the same receiver as before?

And the crystals look alright.
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Offline Razor Concepts

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Re: I need help finding parts
« Reply #14 on: July 12, 2009, 07:23:55 PM »
Duratrax sells a 2000mah nimh battery for about $20, it will last longer compared to the $12 nicd.

The charger is ehh... it is a "dumb" charger, it simply charges the batteries for 30 minutes and basically stops. You want a peak charger that detects when the battery is fully charged. A good budget peak charger is this one:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXWTD9&P=7

You can purchase higher-end chargers on the onyx line if you want more features, but that one above will do fine for now.

The radio system you linked already comes with crystals, so you don't need to buy them separately. Also when buying crystals, there is another little difference besides the channel number. Crystals can have a positive shift or negative shift... see here
http://www.rcs-sports.com/understanding_neg%20and%20pos%20crystals%20path.htm

So it is best to purchase crystals of the same brand as the radio and receiver.
« Last Edit: July 12, 2009, 07:26:08 PM by Razor Concepts »

Offline kanekTopic starter

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Re: I need help finding parts
« Reply #15 on: July 12, 2009, 08:28:57 PM »
Ok, I went over budget a bit but I will be recieving more money shortly so I might be able to get the money for it. This is what I updated my shopping cart to:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMUT9&P=ML
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXWTD9&P=7
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCJG870&P=7

I went over budget by $40 or so but I rather go over budget to make sure I get it right the first time.
« Last Edit: July 13, 2009, 01:59:36 PM by kanek »

Offline radhoo

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Re: I need help finding parts
« Reply #16 on: July 13, 2009, 09:18:52 AM »
A good design idea saves you considerable money.

You need to consider:
-size of your robot
-autonomy (range to operate before running our of "fuel")
-power (getting over obstacles, etc)
-controllers (do you need a PC motherboard running win/linux or an atmega suits you?)
etc


Offline kanekTopic starter

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Re: I need help finding parts
« Reply #17 on: July 13, 2009, 02:03:53 PM »
Ok, I went over budget a bit but I will be recieving more money shortly so I might be able to get the money for it. This is what I updated my shopping cart to:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMUT9&P=ML
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXWTD9&P=7
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCJG870&P=7

I went over budget by $40 or so but I rather go over budget to make sure I get it right the first time.


I know this is good for what I am doing because it will only be a r/c car pretty much. Later it will be upgraded to a different robot that is designed for bigger use. For now it is just a baseic r/c car with 2 wheels and a tail that has a wheel on it.

Offline kanekTopic starter

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Re: I need help finding parts
« Reply #18 on: July 14, 2009, 09:52:48 PM »
Are the parts in my previous post good?
« Last Edit: July 16, 2009, 01:29:07 PM by kanek »