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How to start with the wrong voltage and get it to work?

How to start with the wrong voltage and get it to work?

Sorry for how long the post turned out to be. These first 3 questions are somewhat academic, so please don't scowl at me. :)

Questions D and E are the most interesting, and the only ones I really need solved soon. A and B interest me. I know variation is possible, but have too little experience to even guess how much.

My friend** almost bought a garage door receiver that was able to run on 12 or 24 volts AC:

A. Is it likely that one can run a 12 volt AC garage door receiver off of the existing 16 volt AC adapter with no damage to the receiver?

B. Is it likely that one can run the same AC garage door receiver set for 24 volts, off of the same 16 volt AC adapter, and it will work? Will reception probably be a lot weaker? :)

C. Is it likely the difference between the 12 and 24 volt settings is just a resistor in series for the 12 volt setting, and I could replace that with a lower ohm resistor so it would run fine on 16 volts??

D-setup. We may be able to change the transformer to 24vac. This is a garage door receiver with no garage door. The receiver is inside the house on a closet shelf near the front wall (1960's house, brick) and includes relay A in it which controls another relay B in the basement which controls a rated 24-volt latching relay C that turns on floodlights outside the house. They use them when they come home, especially the wife who's a bit scared and also doesn't walk well.

D-question. So, if relay B's coil was set up to run on, has been running on 16 volts AC, is there any chance changing it to 24 volts AC could cause a problem? The relay is only closed for 2 to 5 (10 maybe, if someone is berserk) seconds once or twice a day when someone in a car pushes the button on the remote.

E-setup. It turns out that he found at Radio Shack a unit, with only one remote, for only 3 dollars! Closeout. What luck. First store he went to. It runs on 12 volts, AC. His electronics friend at work tells him about a voltage divider, but my objection is that will mean the AC transformer is providing output current ALL the time.

E-question. I would rather start with a high value resistor in series between the 24 volts and the 12 volt device, lowering the value^^ until there is 12 or 13 volts across the device. Seems to me, this receiver always uses the same current, except maybe when closing its relay, but that shouldn't draw enough more to lower the voltage enough to cause a problem. If testing shows it does lower the voltage, then I would consider setting the usual voltage at 13. Is my way likely to work? and assuming it works, woudln't it be better? Not waste electricity?

^^This would also give me a chance to use my resistor box that I got at a flea market and have only used once. :)

**For some reason after my friend bought this house he went around the house removing anything he didn't like, including the receiver for this light setup, and then he threw it away.*** He also disconnected the alarm tape on the windows saying that tape was obsolete, even though he didn't replace it with anything, or even remove the rest of the tape!! I'm seeing a whole new side of this guy.

Normally I'd do almost any amount of work for my friend -- he also does a lot for me -- but I don't feel like putting in more effort than necessary to overcome his stupidity!

***The transmitters, 10 or 20 or 25 years old, are still sold, but we can't find a receiver that works with the transmitters. New ones are 310 megahertz and these are 303.xxx megahertz. New receiver sets are as low as 60 dollars, or 32 on ebay for some left-over Viper car alarm fobs that they matched up with a garage door opener receiver. Good for them, not wasting the stuff.

Frankly the whole thing seems like a good idea, for a lot of people who are afraid to come home in the dark, or need the light not to trip.

F. I presume the relay is there because the installer, maybe the burglar alarm installer, thought that the garage door receiver mechanical relay couldn't handle the current for the 24 volt latching relay C. Does that sound right?? Now that the relay is there, in its own metal box, I see no reason to eliminate it. but do you think the installer was likely to be right? I ask because for my car alarm, I was afraid to power the door lock solenoids, two of them, pretty big, from the mechanical relay in the alarm box, and the instructions weren't perfectly clear, so I put another relay in between.

Thanks a lot for any help.

Reply to
mm
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What do you mean by a "16 volt AC adapter"? (It's a power supply, not an adapter, but that's another matter.) Do you mean a transformer that drops the power line to 16 volts AC, or a power supply that puts out 16 volts DC?

There's a possibility it would work, but you're taking a chance of, at the very least, overheating the receiver. It's better to find the appropriate power supply.

The reverse of the above. There's a good chance the receiver won't work at all.

Who can say without looking at the unit? But the odds are vanishingly small. It is uncommon to change voltages with a dropping resistor.

First, find out whether the external supply is AC or DC. Then get the right unit. Don't fool around.

Your questions are "unreasonable", because you haven't given us a detailed description of this equipment. It's like asking a doctor to diagnose your illness, but you haven't supplied any symptoms.

Find some neighborhood electronics expert and have him look at it. Then treat him to a nice dinner (there's a 2/$3 Big Mac deal at some McDonald's), whether or not he's able to answer your questions.

Reply to
William Sommerwerck

First off, I believe the receiver kit your friend got from that Shack store is a switch, not garage door opener receiver/controller. The switch is a momentary close-type switch, not a open or closed switch as a choice. Secondly, that store often sells customer returned, non-working products for clearance prices.

So, the only thing that remote controlled switch is capable of doing, is mimicking a person pressing a switch for an instant (push, release). So, even though you my have a latching relay at some point, the proposed light controller circuit would require an additional switch circuit run to a convenient location, to release the latched relay.

I recently purchased one of the SkyLink products, and the receiver for the switch is capable of being powered by an existing GDO's switch leads, or a separate 12VDC wallwart/AC adapter. When it's powered by the GDO, all it does is act like a momentarily closed switch to activate the GDO. It's the GDO that controls the light and door, not the Skylink remote/switch. When the SkyLink receiver/switch is powered by a 12VDC separate supply, it provides a momentarily closed switch contact, not an on state, that changes to an off state when the button is pressed again.

It appears as though you're in a spot where you'd like to help your friend, but he's only providing you with a pile of old, and/or mismatched, miscellaneous parts.. that all combined, won't exactly replicate a working garage door controller/ light controller. You might consider that when some old parts fail to work properly, it may be interpreted as being your fault, and/or your problem.

There are numerous products for controlling lights with a small, keychain-sized remote control. One button for on (stays on), and a separate button for off. These products are generally plugged into a wall receptacle, then a lamp fixture is plugged into the product.

As for the comment regarding a power supply that uses electrical power when it's not being used, you can replace that with a moderately well-trained dog that's been trained to turn on a switch when he hears someone approaching the house.

-- Cheers, WB .............

Reply to
Wild_Bill

Without available schematics and specifications on the affected components, no one can tell you what can or cant be done in that respect. Most equipment will tell you in the manual not to use a transformer other than what was supplied. But, most electronic equipment designed to run on 12 or

24 vac just swap a diode inside before becoming a DC supply. Some will run just fine even on a DC transformer, but you need to know what is going on inside the unit. What would be wrong with running the receiver from its own 12vac wall wort?
Reply to
JB

Good to know. I will check.

I'd have to find one. Like I say, I"ve done enough work on this project.

Turns out the 3 dollar one isn't exactly what would work best, so he's buying the 32 dollar one. It may raise different questions. I think it takes either 12 or 24 volts though.

If I don't answer each of you, thanks to everyone for answering.

Reply to
mm

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