Info req'd on keyfob R/C

ROSS said:
Tony Walsham said:
R/C's with oddball VHF frequency will generally be legal if they limit the on time of a button press signal transmission to no more than 1 second and the off time to be at least 10 seconds before the next button press.
If they do not comply with that, they would likely be illegal.
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What is legal in one country may be illegal in another. They are pretty stringent here in the UK.
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I would think the rules are similar here too - but it is the rural west - all rules observed (in the breach):rolf::rolf::rolf::rolf::rolf::rolf:
 
trammayo said:
Hi Rik - I'll be testing again today! What was the range that you obtained for switching it on and off?
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Max is about 10m. However, to achieve this I removed the circuit board and stretched out the aerial (which is coiled like a phone lead). The signal does seem susceptible to interruption though so sometimes I need to wave the keyfob about in the air sometimes to get the receiver to respond.

Rik
 
That's great Rik - was wondering about the aerial and if something could be done!

Many thanks:thumbup:
 
Always the Way Spoz... set the search criteria to "cheapest + Postage" first....
 
G'day Trev or G'night!
 
23A batteries are the small cylindrical ( 12Volt) ones used in garage door openers...
 
ge_rik said:
trammayo said:
Hi Rik - I'll be testing again today! What was the range that you obtained for switching it on and off?
Click to expand...

Max is about 10m. However, to achieve this I removed the circuit board and stretched out the aerial (which is coiled like a phone lead). The signal does seem susceptible to interruption though so sometimes I need to wave the keyfob about in the air sometimes to get the receiver to respond.
Rik
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I unscrewed it and stretched out the aerial. I think I was a bit too clever for my own good - I'd stretched it straight, drilled a tiny hole in the case, and pulled the wire through - it didn't respond to OFF! So I pulled the wire back in the case and looped it inside - result:thumbup: Yesterday, although the range wasn't great, it would stop or start without waving the keyfob. Now I have to wave it about (only for the stop function). I wonder if the fob battery could be the culprit or have I got a dodgy unit?

I have been told how to test the unit's dimmer - supply around 12v and attach some leds (thanks Neil) just got to get 10 identical AA's together! Apart from the last eight I bought, the others vary from 1500 to 2000ma. Might wait until Thursday (shopping day) and get a pack of 8 1.5v ones.

EDit; Then again, apart being awake, I'm not thinking right! I have plenty of 12v batteries that I use for the trailer. More later when I wake up properly:rolf::rolf::rolf:
 
ROSS said:
ge_rik said:
However, to achieve this I removed the circuit board and stretched out the aerial (which is coiled like a phone lead). Rik
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A lot of probs with rc type receiver aerials is that modellers do not stretch to full length.
That could well be the problem here with the tranny. Never know with these Chinese jobs:rolf:.
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I skipped Antenna design 101 but from what I understand the transmit antenna is more critical. The coiled up receive antenna could be simply replaced by a suitable length of insulated copper wire..... If you were clever enough you could set up some sort of induction loop using the rails. But be honest who wants a range of more than 10 metres? More likely you would keep your machine within eyesight.
The frequencies are as from the receiver board; 433.92MHz, 315MHz.... if that means anything to anyone..... there are no frequencies inside the transmitter but as a suggestion to get max range out of this thing hold it vertically rather than horizontally and aimed at the target ( like you do with a tv remote)
Propogation of radio waves are sort of well try and imagine a doughnut shape with the antenna through the middle so aiming the antenna directly at what you want to control will cut down your hopes especially in a transmitter as low powered as this....
 
trammayo said:
Yesterday, although the range wasn't great, it would stop or start without waving the keyfob. Now I have to wave it about (only for the stop function). I wonder if the fob battery could be the culprit or have I got a dodgy unit?
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Sounds a bit like mine. Sometimes it works faultlessly then at other times it's a bit hit and miss. I've assumed it's interference from track or motor etc. as I can't find any consistency as to when it behaves and when it has a fit of the sulks.

Still, it keeps the neighbour amused watching me walking around the garden frantically waving one arm in the air.

Rik
 
tramcar trev said:
then to thow a variant into the mix: http://www.ebay.com.au/itm/6Key-RGB...ans&hash=item51a69c5c4b&_uhb=1#ht_3345wt_1097
The transmitter has an antenna and there are 3 channels so it could presumably controll lighting etc as well as speed.....
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Just a thought - could you use one of the extra channels to operate a relay of some kind to change direction? No idea how it would actually work, just a random idea that came to mind while reading through this thread.....

Jon.
 
So - it is working - but with variable results. It does cut down the motor current (which is now fine) but it does take a long time to respond on the dimmer controls.

Also, prior to lunchtime, the On/Off had a good range. After lunch, the On function still has a good range but the Off only responds when you are less than a foot away!
 
tramcar trev said:
23A batteries are the small cylindrical ( 12Volt) ones used in garage door openers...
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8| Sure are. Had to get one last week. One of the guys at work here is using a 'garage door' opener fob to run his loco, must get the details.
 
tramcar trev said:
The frequencies are as from the receiver board; 433.92MHz, 315MHz.... if that means anything to anyone..... there are no frequencies inside the transmitter but as a suggestion to get max range out of this thing hold it vertically rather than horizontally and aimed at the target ( like you do with a tv remote)
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That should be OK then; the class licence is here, and both those frequencies are included:
http://www.comlaw.gov.au/Details/F2011C00543
Can't imagine the power limitations would be even approached given the experienced ranges. Nice to know that we are law abiding citizens, after all, I suppose!
 
Zerogee said:
tramcar trev said:
then to thow a variant into the mix: http://www.ebay.com.au/itm/6Key-RGB...ans&hash=item51a69c5c4b&_uhb=1#ht_3345wt_1097
The transmitter has an antenna and there are 3 channels so it could presumably controll lighting etc as well as speed.....
Click to expand...

Just a thought - could you use one of the extra channels to operate a relay of some kind to change direction? No idea how it would actually work, just a random idea that came to mind while reading through this thread.....

Jon.
Click to expand...
Hey great idea a double pole double throw relay would do that nicely, the selected channel turns the relay on/off and gives you reverse/forward... the common contacts would be wired to the motor, the others wired to the output crossed over and the coil contacts wired to the output from the chosen channel.... the remaining channel could turn headlights on or off. Spiffing idea. Virtually full radio control for how much?
 
Just to chuck in a bit about antenna design. Transmitter and receiver antennas should share the same characteristics. However, more effort will go into the transmitter design (usually) because there is only one and often many receivers. There should be a relationship between the length of the antenna and the wavelength of the signal and whether coiled or not it is the length of the antenna that counts, NOT the length of wire. The only exception is for a helical directional antenna where the radius of the helix has a relationship with the wavelength and the signal is transmitter/received along the axis of the helix.

Hence, IMHO, uncoiling the antenna is likely not to improve things unless the new length is (say) twice the original coiled length, which should have been matched to the wavelength/frequency.

Richard
 
Ross,
At 35Mhz a 1/4 wave antenna is around 213cm long. I agree that it would not only be hopeless to coil this length of wire up and have any communication whatsoever, a coiled antenna 213cm long is also impractical on a flying model. Here is a link for practical measurements that some one made: http://www.rc-cam.com/ant_exp.htm, ...as noted in the linked article. Richard
 
rjstott said:
Just to chuck in a bit about antenna design. Transmitter and receiver antennas should share the same characteristics. However, more effort will go into the transmitter design (usually) because there is only one and often many receivers. There should be a relationship between the length of the antenna and the wavelength of the signal and whether coiled or not it is the length of the antenna that counts, NOT the length of wire. The only exception is for a helical directional antenna where the radius of the helix has a relationship with the wavelength and the signal is transmitter/received along the axis of the helix.

Hence, IMHO, uncoiling the antenna is likely not to improve things unless the new length is (say) twice the original coiled length, which should have been matched to the wavelength/frequency.

Richard
Click to expand...
OK - sounds good in theory - but in practice I noticed there was a significant difference in the distance over which the rx picked up the signal when I uncoiled its antenna. Maybe I just struck lucky.

Rik
 
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