# Translation and Explanation of Diagram

Discussion in 'General Electronics Discussion' started by sabrehagen, Jul 4, 2012.

1. ### sabrehagen

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Jul 4, 2012
Hi,

I am studying Computer Science at university and have just purchased a garage door remote receiver. I have a remote in my car, and I want to use this device to receive the signal from the remote and open my garage door. I have a limited understanding of circuitry, so I was wondering if somebody could assist me in deciphering the circuit diagram they sent with it. My two main problems are:

1. Where do I connect the power source. What level of voltage and amps would it be?
2. Where is the 'output' from the circuit, that is, where does the signal to activate the door open come from?

It's likely I've missed some crucial questions, but if you could help me with these, that would be a great start.

Thanks guys!

P.S. Sorry about the blur on the right side of the picture; I think it's still readable.

2. ### sabrehagen

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Jul 4, 2012
Any ideas guys?

3. ### davennModerator

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Sep 5, 2009
Doesnt that terminal in the top righ where its blurry say.... IN 12DC ?

and the information above tells you 12VDC @ 7mA ( static current) which means it may be a little more in use

the mains power and its item to be controlled goes in at the top left as indicated where the relay will switch it on and off as commanded by the remote

Dave

4. ### KrisBlueNZSadly passed away in 2015

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Nov 28, 2011
Yeah, as Dave said, the receiver seems to want 12VDC at 7 mA idle current (more when the relays are activated, so aim for 12VDC at at least 100 mA).
The output is on the two sets of relay contacts labelled A,B,C. Exactly HOW the contacts operate in response to the transmitter button(s) is not clear but you can find out by trial and error. Connect a multimeter on continuity range between the A and B connections and try pressing the transmitter button(s).
If you want to control a garage door, you will need some external logic. Normally a garage door is operated by a motor that turns one way to open the door, and the other way to close it. The activation time of the motor needs to be fairly accurate so that the door opens or closes fully without overloading the motor when the limits are reached. Some doors have limit switches so the logic knows when to stop the motor; some just work by timing the motor run time. The logic needs to be aware of whether the door is opening or closing. Some doors can be stopped part way through their cycle, then restarted in the opposite direction. This all requires logic and is normally done with a microcontroller.
So you need to find a 12V power supply for your receiver, and find out how the relay contact outputs respond to the button(s) on the remote control transmitter, and find out how your garage door motor is powered. Then you should be able to figure out what logic and interfacing circuitry you will need in between the two.
We can help further, but at least find out that information and post it clearly here.

5. ### sabrehagen

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Jul 4, 2012
Thank you Kris, your post was extremely helpful. I was planning to use the "wall switch" input to my garage door controller. I need to look into how this works, but I believe it functions by sending a one off signal to the garage door, and it either opens or closes the door as a result (which ever is the opposite of the current state). Therefore I believe the timing of the garage door motor is still all done internally, and the receiver will only act as the switch which activates this functionality.

Secondly, being the beginner I am, I don't know where to get a 12V power source! Do you go to an electronics shop and ask for a 12V 100mA?

Thanks again!

6. ### KrisBlueNZSadly passed away in 2015

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Nov 28, 2011
OK so you already have a controller for the garage door.
So you will just be "extending" the button, so the button on the remote control transmitter will just be connected in parallel with it. That should work fine; you just need to check that the receiver's relay contacts close while the transmitter button is held down.
Yes, you can get a 12V DC power supply rated at 100 mA or more from any electronics shop. That's what you ask for.

7. ### sabrehagen

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Jul 4, 2012
Okay, jaycar is selling them for \$25, and eBay has them for \$2.99 (http://www.ebay.com.au/itm/AC-100-2...ltDomain_15&hash=item20bb364cba#ht_2822wt_905)

Is there a way to strip open the cable and get the + and - wires for my circuit board?

I didn't quite understand what you meant in your first sentence when you said it would be wired in parallel. The "wall switch" option is an extension to the garage door unit that allows you to have a wired switch to make the door go up and down (as opposed to the remotes). There is currently nothing connected to the "wall switch", and I was planning to connect this new receiver to it. That way, anything that triggers the receiver will open the door. Can you clarify the "extending" idea? I didn't really follow.

Thanks - I'm getting close to a solution!

8. ### KrisBlueNZSadly passed away in 2015

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Nov 28, 2011
Wow, AUD 3! That's very cheap! And I don't necessarily just mean that in a good way!

Yes, you can just cut the plug off the end of the cable, strip off the outer insulation, separate the screen from the centre conductor, twist up the screen wires, strip the centre conductor, and connect the screen and the centre conductor to the connector for the receiver. Check the polarity with a multimeter.

My comment about "in parallel" was assuming you already had a wall switch connected to the "wall switch" inputs of your garage door controller. Since you don't already have a wall switch, nothing is being connected in parallel with anything; you're just using the relay contact of the receiver as a "wall switch".

You're right, you should just be able to connect the receiver's contacts to the "wall switch" input. But first, make sure that the contacts close while the remote's pushbutton is pressed, and open when it's released.

Last edited: Jul 5, 2012
9. ### CraziestOzzy

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Jul 4, 2012
MATE....DO NOT USE THIS DEVICE....

When my daughter was five, she wrote better english than what is written in the instructions.
Using mains power supply connected directly to the relay as shown in diagram you provide is just nuts. Playing with mains power supply and asking in a forum "Where do I connect the power source?" tells me you should get some marshmallows out of the bag or at the least, get the eggs out and a frying pan and wait for the fire works if you wire up this device and power it on.
At least you will save on power in cooking your dinner.
Sorry for being brutal, but I feel you need a gentle nudge

10. ### sabrehagen

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Jul 4, 2012
Thanks, I can follow all of that, and will be able to put all of that into practice. Yes, very cheap can mean good and bad things. Given that the circuit cost \$7, it's in keeping with the budget of the project, and hopefully won't fizzle out or damage the circuit! Sorry for the confusion with the in parallel section. I'll make sure to do the contact test to make sure it functions as expected. I really appreciate all your help, you've been very in depth and given me a much better understanding of what I'm dealing with!

The instructions come from China, so they are written by somebody trying to be industrious and get ahead in the world, so you'll have to excuse their ability to accurately describe circuitry in their second language, something I think your five year old daughter might have some trouble with. My understanding of the diagram was already such that I believed I knew where to connect the power, but I thought I'd ask more experienced people to ensure I was right. As they say, there are no silly questions, only silly answers. You appear to be familiar with this, your response is a fair example. I appreciate your concern with my lack of ability and the caution that I should take, but everybody must start somewhere. It's good to be reminded of the dangers of electricity; something easily overlooked. Thank you for that. From your six posts, I can see that you don't yet provide the same level of assistance as somebody like Kris. Maybe in time your answers will become as helpful and supportive as his.

11. ### KrisBlueNZSadly passed away in 2015

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Nov 28, 2011
sabrehagen, thanks for your kind words about me, but I'm afraid I have to disagree with your rosy interpretation of the reason for, and implications of, the bad English on your remote control receiver (and other cheap Chinese products).

The very poor English on the label of your receiver is actually a sign that the manufacturer either doesn't know that his English is beyond being understood, or can't be bothered or can't afford to have it professionally translated. In any case it is a clue that the people responsible for the product are unprofessional and irresponsible. I think in those circumstances, the question "what other shortcuts have they taken, and what other quality and international safety standards are they unaware of?" is a fair one to ask.

In this case, the receiver only uses 12VDC so there isn't an immediate safety issue there. But your \$3 mains power supply is something I would be concerned about. As an example let me tell you about a laptop power supply I bought recently. It was a no-name Chinese product imported locally and sold for NZD 36 which is VERY cheap for a 120W switching supply. The mains cable that was supplied with it wasn't properly wired, and shorted out with a bang when I moved it. The importer replaced it, but even the replacement one would fail a basic safety test. After a few bends, the outer insulation (which is quite stiff) simply broke at the join with the connector, then the inner insulation started to break apart too, creating an immediate shock and fire risk. The reason is simply that the insulation on the cable is too inflexible. This type of budget-related shortcut is common among cheap Chinese-made products. The power supply itself gets much hotter than it should. I will try it in my application. I don't know whether it will be usable or not.

I want to make it clear that I have no dislike for Chinese people, and I'm also aware that China is capable of making very good-quality products when the people and companies involved are held to high standards and properly funded. I have owned several Palm Treo smartphones that were made in China and were of very good quality. I believe Apple get their hardware made in China. My criticism is of products designed by amateurs to an extremely tight budget with little regard for quality, reliability and safety. The attitude of these people seems to be that if the product LOOKS like something good, and at least SEEMS to work, then it's alright to sell it.

Here in New Zealand we have a lot of "two dollar shops" where low-budget Chinese products are sold. My own experience is that electronic devices bought from these shops sometimes don't work right out of the box, and if they do, they usually fail within a short time. They are usually made with obvious weaknesses and failure points. They are clearly made with little or no regard for quality or safety.

We also have a chain of shops called The Warehouse, which also sells a lot of Chinese-made products. They are regularly on the news because of safety failings in products like children's bicycles, toys and prams. Many of their other Chinese-made products fail just as badly, and are made to equally poor quality and safety standards, but don't get on the news because they aren't an immediate danger to children. Cheap Chinese-made products generally have a very poor quality and safety record here. Some use obsolete components and chemicals that are banned. For example I bought a portable vacuum cleaner that worked for a month or so, and contained Ni-Cd (Nickel-Cadmium) rechargeable batteries, despite the fact that these had been banned for years because of the danger of Cadmium in the waste stream.

It's nice to imagine lots of responsible hard-working people in China just trying to get ahead, and that may be true, but from our point of view, as the recipients of the cheapest possible Chinese products, which are designed and manufactured with no sense of pride or responsibility, we don't see it.

Last edited: Jul 6, 2012
12. ### CraziestOzzy

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Jul 4, 2012
No worries sabrehagen...
If you insist on using the 240 volt to feed your relay, use in the very least an isolation transformer. I recall looking at these relay units ages ago. There are some units that come with minimal safety components I list from the top of my head, such as
fuse
surge protector
EMI filter
Current limit resistor

May I suggest you use an old ATX computer power supply? They have all the safety stuff in them. The 12 volt output has good amperage too that can directly drive a 12 volt DC motor up to 7amps or more, depending on the ATX. Select all the yellow leads and join them together to increase the power rating of the 12 volt cable. Do the same with the black cables. Use a continuity tester typically found in any multimeter to make sure the leads are the right ones and in the same circuit. You can lift up the cover too, but be careful...residual power may be stored in the caps and will wake you up.
The good thing with these supplies...even the 12 volt dc outputs have protection inbuilt...including reverse polarity, current overload to name a few.

Check the rating on the other relay bottom of the photograph....if I understand Chinese translation, I think that may have a 12 volt input to the relay as an option to not using 240volt ac.

Use the 12 volt ATX supply to drive the relay and drive the motor.
And added bonus is that most ATX have a 12 volt low amperage signal cable that can be used to trigger the relay...this keeps the relay supply seperate to the motor feed supply.
. Use a FUSE the Chinese did not include into their circuit.

...and if you just want a 12 volt supply to trigger the relay (if it is 12 volt input), use any old wall adapter that is rated for 12 volt dc output. I am sure will have a few laying around the house. The relay will only consume what it needs, so you can get one rated up to one amp output if you like. AND USE A FUSE.

Have fun tinkering....safely

...forgot to mention (been bugging me, hence the edit), place an electrolytic capacitor in circuit for the relay...makes the relay last MUCH longer and reduce contact burn/arcing....plenty of info on the web how and why to do this.

Last edited: Jul 7, 2012