Test a garage door remote? - Page 1
Forum section: electronics / beginners

author: somlioy
author_rank: Regular Contributor
timestamp: September 26, 2013, 02:56:52 pm
content: HiGot a garage door remote transmitting on 40.685Mhz, whats the best way to read the signal on a scope, or rather to check if its actually transmitting to confirm whether the remote or the receiver is dead.

author: bugfix
author_rank: Newbie
timestamp: September 26, 2013, 03:39:41 pm
content: Something like this maybe?http://www.ebay.com/itm/Mini-Frequency-Counter-Tester-For-Two-Way-Radio-Transceiver-GSM-50-MHz-2-4-GHz-/300899054550

author: KJDS
author_rank: Super Contributor
timestamp: September 26, 2013, 03:45:07 pm
content: If you have a scope available then wrapping the ground lead of the probe round the transmitter should give enough coupling to see the burst on the scope.

author: bookaboo
author_rank: Frequent Contributor
timestamp: September 26, 2013, 10:53:57 pm
content: If you can borrow a multiband scanner like the ypt people use to listen into airshows and such. You can hear the tone of the data if it can be tuned to that freq.In practical terms may be better to buy a cheap kefob+receiver on ebay/aliexpress and wire it in externally.

author: DaveW
author_rank: Frequent Contributor
timestamp: September 27, 2013, 07:15:29 am
content: Build an RF dectector (a capacitor, resistor and diode) like shown in the wiki article,http://en.wikipedia.org/wiki/RF_probe. This will give you the rough envelope of the signal and will easily work up to 40MHz

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 27, 2013, 07:52:10 am
content: Quote from: somlioy on September 26, 2013, 02:56:52 pmJust the fact that it is transmitting will not tell you if the problem is with the receiver or the transmitter since it could be transmitting on the wrong frequency or it could be transmitting the wrong code.

author: amyk
author_rank: Super Contributor
timestamp: September 27, 2013, 10:35:57 am
content: Quote from: PA0PBZ on September 27, 2013, 07:52:10 amIf the scope has a high enough bandwidth you should be able to view the modulated signal.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 27, 2013, 11:08:17 am
content: Quote from: amyk on September 27, 2013, 10:35:57 amWhich will only tell you that there is some kind of modulation, not that it is the correct signal for the receiver.

author: G7PSK
author_rank: Super Contributor
timestamp: September 28, 2013, 08:58:31 am
content: Buy a new remote, most these days can be cloned from another remote, then use the new one to try the receiver. Also check that the receiver is set for your remote most have program or learn button that you press on the board then you press the remote transmit and it learns the code, I have seen many instances of the receiver or the transmitter forgetting the code due to power glitches or battery failure. All the control boards that I have used have an led on them that flashes when the signal is received from the remote so this will tell you if the transmitter is sending and the board receiving the signal.

author: somlioy
author_rank: Regular Contributor
timestamp: September 28, 2013, 09:04:40 am
content: Yeah I've tried relearning the remote. The light is supposed to blink when the remote is paired, but it dosent. The code is set by dipswitches on the remote.

author: G7PSK
author_rank: Super Contributor
timestamp: September 28, 2013, 09:26:16 am
content: An old style remote then, all the new ones seem to be the cloning/ self select type with no form of manual code setting, from my own experience I would assume the remote is dead, I have had gates where the main board has been killed by lightning strikes but the receive daughter board has survived intact, and many remotes that have died from cold by being left in the car or tractor overnight. I have made many remote operated gates over the years and the ratio of remote to receiver deaths must be greater than 50 to one never really kept score on it but one farm regularly buys 20 remotes at a time mostly loss is due to misplacing them but quite a few just die from cold or heat, dirt etc.