Need help boosting the signal on my electric skateboard.

[protocol217]

I have an electric skateboard that is controlled with a handheld remote controller that looks like this:

It is powered from a 9V battery. and from the side it has like piece of aluminum foil that serves as antenna i think.

The receiver on the skateboard looks like this:

the blue wire (J1) is the antenna i have tried many antennas for WiFi, Bluetooth 3G/4G, best range is with the original antenna ( the isolated red wire on the picture), but the problem is that the range is 60 cm maximum and the signal sometimes cuts out when i am driving and that's very annoying.
i have also tried adjusting a Little those pots but it makes it only worse also on the transmitter, so i returned everything to original settings.
And i tried boosting a voltage on the transmitter from 9 to 11V but that also does not help.
And last i connected the antenna of the transmitter to the antenna of the receiver with copper wire and that extends the range as much as the wire is long but i don't want to have a wire attached to my skateboard a want it to be wireless RF controlled.

What should i do to get a little more range out of this remote at least 1 meter?

 

[tcmtech]

A picture of the transmitter circuit board from each side is what we need to be able to trace the circuit.

I'm guessing it's probably a very simple transmitter that more than likely uses a single power limiting resistor on the RF signal generator which if so just putting a lower value resistor will increase the range.

I've done that to many of those cheap remote on/off power switch transmitters over the years and a few simple remote control toys transmitters as well.

 

[protocol217]

The red and black wires on the right are 9V battery leads. the wires coming in the board from the left side are from the power switch and the pot that regulates the speed and break. The metal switch on the right is for choosing the speed mod L/M/H.
And in the right lower end of the board comes the antenna after C11.
I hope the pictures are good enough if not then i will desolder all the wires from the board and take it out and make some more pics.

 

[alec_t]

Looks as though the antenna is fed via R18 and C11 in series? What are the markings on R18?

 

[protocol217]

R18 is marked as 104

 

[alec_t]

That's 100k. Perhaps tcmtech can tell us if that's typical for an antenna power limiter?

 

[tcmtech]

Sounds about right for something with a ~1 meter range. Try putting a 10K in its place or parallel to it and see if the range goes up.

 

[protocol217]

No, i have put the 10K resistor in parallel with r18 and the signal is then completely lost, when i disconnect the 10k resistor i get back the signal for 40-50 cm range.

Also tried more values and direct connect with no resistor and no result, the best range i get is with the original 100k resistor 40-50 cm.

Any more suggestions?

 

[tcmtech]

Then R18 is not the power limiting one.

Personally I cant read the circuit layout worth a darn being its largely surface mount and not in my hands.

Can you follow the DC power input to that part of the circuit instead? If there's a single resistor in series with that power feed that would be the one to try bypassing next.

R12 maybe? It's the next one I would try as it appears to be tied to a transistor that's connected to a line coming off the main inductor that should be the main driving component of the LC tank transmitting circuit.

Still guessing really.

 

[protocol217]

I just tried R12 it is not the one.
And i tried every single resistor on the board to parallel connect with 10k resistor and no result.

 

[tcmtech]

Guess your stuck with it.

 

[JimB]

Looking at the pictures, both the receiver and the transmitter are very simple (cheap) designs.
Their operating frequency appears to be determined by the variable inductors and associated capacitors. If you have been adjusting any of these, it is possible that the transmitter and receiver are on slightly different frequencies, so reducing the range.

I have never seen one of these things on my workbench, so I cannot give you any good suggestions to improve the performance.
Just blindly changing components is unlikely to give an improvement.

JimB

 

[protocol217]

Today i have experimented a little with the transmitter and instead of R18 which is 100K i soldered in a 100K pot and looked for best result, and i found out that i get 10cm more if a replace the 100k resistor with 30k, but not more or less, when i put 20k or 40k it gets worse, so now i soldered a 30k resistor to R18.

That still not enough range i would like to get minimum 1 meter.

Any suggestion on what to do with the receiver board to make it better?

 

[tcmtech]

Interesting.

Have you tried retuning the choke when you have the lower value resistors in? Maybe the added power is causing some frequency drift in the the LC tank circuit and it needs to be brought back into the receiver's range again.

 

[protocol217]

So, i adjusted all the chokes for the best range.
I am now able to get 70cm from it and i was for a test drive and works good when i am on the board, no more signal cut out but, from the receiver board i have hot glued the antenna wire on top off my skateboard so that i am standing on it while driving.
And i think that now the signal goes through me when i am standing on the board, as soon as i step off the board and the antenna wire i get lower signal.

Oh, and i forgot to say i have also installed a Bluetooth amplifier with speakers on my skateboard that should not cause interference should it?
Bluetooth works on 2.4Ghz and the skateboard i think is 315 or 433Mhz frequency. I also tried disconnecting this Bluetooth module but no improvement in signal.

So for now i am able to drive without signal cut outs but i still want to make the signal stronger to about 1 meter or more.

Any suggestions on the antenna that i should get for transmitter / receiver?