transmitter, reciever and electronically controlled toy train

[spke1816]

I am starting my final quarter to get my associates degree and I have some ideas for my final project. Looking at my son's toys I thought it would be a fun project if I built a transmitter that could send two specific signals (I don't have any chosen already) and the signal would then be recieved by a small enough reciever that would fit on the side of a wooden thomas train. the outputs of the reciever would then trigger either a forward or reverse motion in a small motor that would be fixed underneath the train.

I'm totally excited to work on this and have built a couple transmitters and recievers in my classes but have no experience with motor control and am unsure how to design the transmitter to send out two signals depending on a switch or something similar and I am also wondering if instead of having the reciever output to a speaker- would it power a small motor instead?

Any help would be greatly appreciated. I'm not looking for someone to do the work for me, but hoping to get some help being pointed in the right direction, also trying to make this as easy to control as possible since I want my 3 year old to be able to operate this as welll

 

[ronv]

If you Google ASK OOK you will find some very simple circuits (Like used in garage door openers) that you could start with. See what you think.

 

[SABorn]

I have used many of the cheap 433mhz modules (RX and TX) with Picaxe chips and both are very easy to use.

If you went this way then there is few limits to the number of functions you can implement.
For example:- forwards and backwards, flash some led headlights, toot the horn, almost any function within reason.

I have used them for sending wireless data for loggin as well as simple tasks like switching things on and off.

The TX end would only need a 8 pin picaxe (08m) and would allow for 4 buttons and 1 pin to send the data to the TX module.

The RX end only needs 1 pin for the RX module to send the received data in on, and as many pins needed to control the functions you wish to add.

To drive a small motor the easy way would be to use a motor driver chip like a L293D as it has a built in H bridge to give forward and reverse, and it can be a DC motor or even a stepper motor. (DC motor would only use half the L293D or it could drive 2 DC motors or 1 stepper)

Pete.

 

[spke1816]

I'll Definately look into that. Thanks

 

[SABorn]

This is the sort of RX and TX modules i was reffering to, and they are available everywhere.

**broken link removed**

 

[spke1816]

these are definately some great ideas and I thnak you for that. I will continue to look into these ideas. For my project however, my teacher is requiring that I build both the transmitter and reciever from scratch and the pre built transmitter and recievers that are offered would not be acceptable

 

[SABorn]

Ok, understood!

That was not clear from your original post, but had a feeling that could have been tha case.

Good luck.

Pete.

 

[LLARSON]

ron is right. ASK OOK is the way to go.

The receiver will be your bigger challenge- look at the max1473 ic, and several others similar to it. You'll want the log amplifiers that are built into it, and the data slicer will come in handy, as well...also, rely heavily on the parts about recommended layout...

 

[ronsimpson]

DCC is another way to control the many trains with out RF.

The DCC signal applied to model railroad tracks is both power for your trains and control information. It is actually a pulsed alternating current (AC) squarewave which is a +/-14v signal. The ones and zeros that make up the DCC signal's command data packets are created by modulating the width of the pulses. Narrower pulses are ones and wider pulses are zeros. This encoding scheme is used instead of + for ones and - for zeros because it allows the decoder in the locomotive to read the same information from the tracks regardless of the locomotive's direction of travel.

In the train there is a very simple u-computer that reads the serial data on the track and adjusts the power to the motor.

 

[spke1816]

I would love to be able to make use of the tracks like in typical model trains, however we are using a wooden toy train set that is designed for children to push the train along by themselves, and the car itself is what needs to have the reciever and motor attached. the transmitter after construction will be attached to the table itself that the train set is already resting on

 

[spke1816]

with construction of the reciever and connecting it to the motor, would it be better for it to differentiate between two different signals to determine the direction of the motor or just have one frequency and have the the transmitter only send out a pulse and have the pulse on the reciever tell it to stop and then reverse?

 

[carbonzit]

Hey, "spke", did you consider the suggestion I gave in that other thread, using the Micrel transmitter & receiver? It would make this so simple: no generating pulses, tones, decoding, none of that crap. Just two chips for the receiver. If you're interested I could give you more details.

 

[spke1816]

I am definately interested, at least on the reciever end the simpler the better since it will be built onto a small thomas wooden train, but at the same time as I had mentioned before I can't use any pre-built chips to do the job, even though it would make things smaller. If you look at my other thread I've added some things I'm looking into as well as far as types of circuits.

thanks to everyone who has helped me so far