"Hamster House" remote control...shade tree mechanic style

Thread Starter

kalikid1210

Joined Jul 15, 2008
21
Happy Holidays to all of you.

I have an exciting project (we all believe that about what we're currently fiddlin' with) in which I want to operate a servo wirelessly with a homemade transmitter. It will eventually operate a rocker arm that actuates a door (open AND close it) for my son's hampster tunnel. I know, kids love the bizarre things and we love to build them.

  • A basic, plain jane Futaba S3004 Standard Ball Bearing Servo
http://www.robotmarketplace.com/products/0-FUTS3004.html
  • Two GWS Receiver Crystal channel 65 UM-1 75.490 Mhz crystals to operate the RX and the TX:
http://www.robotmarketplace.com/products/0-GWX1R75490.html
  • A GWS 75Mhz 4-Channel Pico Receiver - Vertical Pins, Futaba style
http://www.robotmarketplace.com/products/0-GWR4PII75F.html

HERE'S THE CHALLENGE

Most of you that are familiar with R/C toys know the missing component is the transmitter. I own several R/C cars and could scavange the parts from my radio systems BUT my wife would cut off my allowance for destroying my cars...which were NOT cheap!

So fabricating a transmitter assembly is my goal. I know that there's one of you out there with the informational resources to steer me in the right direction.

My guess is I'd need a small circuit board (The part inside my pistol grip transmitter which I cannot pirate) which connects to a crystal, and battery. And not needing it to be digital, an analog type of device, upon which a dial can be affixed to send the "open and close" action signal to the servo.

Cost is a major factor as you can see from the links I posted. I want to keep the cost as low as possible since this is not a crucial project for Snaps the hamster...but dang it, I have to help contain this beast!
 

KMoffett

Joined Dec 19, 2007
2,766
What distance do you need for the Tx/Rx system? If it's only a few feet, I've used the tiny, cheap (often <$10US) ZipZap R/C car transmitters and receivers. Four outputs with a few transistors and resistors. 8 outputs, if you add a couple of CMOC IC's and diodes.

Ken
 

Thread Starter

kalikid1210

Joined Jul 15, 2008
21
hgmjr-

Thank you for the heads up. I have contacted rentron and hope to hear back from them soon. Kudos to you for the info!
 

Thread Starter

kalikid1210

Joined Jul 15, 2008
21
KMoffett- So basically you buy the very cheap cars then dissassemble them for the parts right? Or is there a place where you can buy just the TX, RX etc?

Thanks man
 

KMoffett

Joined Dec 19, 2007
2,766
KMoffett- So basically you buy the very cheap cars then dissassemble them for the parts right? Or is there a place where you can buy just the TX, RX etc?

Thanks man
Yes, but I don't think you could buy them any cheaper. Actually, I got mine at Goodwill for $.99. But, I used to see them for less than $10 retail. These are the ones without proportional steering. Radio Shack still has them: http://www.mini-rc-cars.net/?gclid=CMKS14CS0JcCFQsMGgodIzdoBw
If you decide to go that route, I can post my schematics.

Ken
 

KMoffett

Joined Dec 19, 2007
2,766
The 2 outputs for the steering (non-proportional) are open collector transistors (or mosfets). The Forward/Reverse is some sort of H-bridge, but it looks like there only two transistors for it. ??? These are the output voltages for the F and B terminals with respect to -V:

...FWD...NEU...REV
F 1.50v 0.80v 0.00v
R 0.00v 0.80v 1.50v

The receiver's transistors bring the outputs up to logic (5V) levels. The ICs and diodes decode single and combinations-of-2 button pushes. The IC's are only needed if you need 5, 6, 7, or 8 outputs.

The second schematic is using a PICAXE microcontroller for decoding.

Ken
 
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