This is my second post(thread), so I getting used to how this works.

For a summer electronics project, I've decided to do a remote control robot. All the electronics/mechanical are taken care of, and now for the remote control.

I took these transmitter/receiver from an old toy. The problem is I'm only able to get about a few inches or less of range. The frequency is 49Mhz.

My knowledge in RF communication is minimal.
The antenna on the transmitter is a 18gauge enable copper wire, 30 cm long. The receiver in a small coil on a iron core with a wire sticking out.
There was a label on the IC's, KL49M

How would I go about increasing the range?
Would changing the antenna's help?
Would increasing the signal going to the antenna help?

Thanks to all replies!
Pictures below:

 

If the antenna is the problem, how could I improve it?
If it is the signal, maybe a schematic of an amplifier?

 

I've tried to add a 2n3904 to amplifie, but nothing changed at all!


I would like at least ~20feet, 50 would be great!

 

The receiver seems to have no antenna connected. Try a 30cm length of wire connected here:

 

The receiver seems to have no antenna connected. Try a 30cm length of wire connected here:
View attachment 132860

Thank you for spotting that out for me!
I'll hook up an antenna and see the range.


When your looking in a bag for something, even though you touched it many times, you still keep looking.

 

I put the antenna, got a good 10 feet, but once I go a little further or input more than one signal, the LED(connected to the receiver) starts to blink. I don't have an oscilloscope or anything to measure the frequency it is blinking at, but it is quite slow.
What might cause the LED blink at a certain range?

 

This is what I got from the EE toolkit app.
There is some noise from the motors.

 

I don't know why it would blink.
You could try changing the receiver antenna length, say 25cm or 35 cm to find the best range.

 

I'll see if I can send a better one

 

I'll see if I can send a better one

I'll see about adding a long antenna for better range,
Maybe a different antenna design could help?

 

I'll see about adding a long antenna for better range,
Maybe a different antenna design could help?
View attachment 132920

The spikes are the on/off from the speaker I attached.

 

Also put both antennas vertical and away from anything metal for best range.

 

Could a loop antenna or coil antenna improve the range on the receiver side?

 

Could a loop antenna or coil antenna improve the range on the receiver side?

The antenna needs to be matched to the receiver so without full details of that design it impossible to say what would be the best aerial.
Usually, the antenna used for 49MHz remote control receivers is a wire of some length.

Do you know what was used as the original receiver antenna?

 

The wavelength at 49 Mhz is 300000000/49000000 = 6.12 metres. So a quarter wave ground plane antenna would be 1.53 metres. This would not be practical on a toy so a non resonant antenna would have to be used or an antenna less than a quarter wave long with a loading coil to make it look electrically like a quarter wavelength. It would probably be better to us a higher frequency transmitter and receiver. Possibly around 433 Mhz so a quarter wavelength antenna would be shorter. (1/4 wavelength at 433 Mhz is 17.3 cm.)

Les.

 

The antenna needs to be matched to the receiver so without full details of that design it impossible to say what would be the best aerial.
Usually, the antenna used for 49MHz remote control receivers is a wire of some length.

Do you know what was used as the original receiver antenna?

That is another problem, when I was little the antenna came off and we ended up throwing it away, the receiver antennae came of(saw a solder joint underneath but no antenna). I've seen images of a retractable antenna for 49mhz(photo below) but never got the actual length of it.

Maybe I can use a pair similar the photo I posted below, but for radios?

 

The wavelength at 49 Mhz is 300000000/49000000 = 6.12 metres. So a quarter wave ground plane antenna would be 1.53 metres. This would not be practical on a toy so a non resonant antenna would have to be used or an antenna less than a quarter wave long with a loading coil to make it look electrically like a quarter wavelength. It would probably be better to us a higher frequency transmitter and receiver. Possibly around 433 Mhz.

Les.

I had one of 433Mhz but ended up burning up the encoder on it(power rail was mistakenly connected to the wrong pins)
And because with these I can send up to 3-4 inputs to my robot(to control each track like a tank)
The previous one offered only one input at a time.