S2kRob

Hey all,

I am attempting to perform the Modifry mod to hardwire up my garage door opener, but my opener is a little more complicated than the average opener.

It's actually a 3 button unit from Sears.

The 1st button opens my side of the garage. I would like this button to be activated by the top cruise control button.

The 2nd button opens the other side of the garage. I would like this button to be activated by the bottom cruise control button.

The 3rd button will go unused.

So, I think that I need to supply the remote with a constant 3v power supply due to the fact that there are a couple of chips on the board (the large one I assume is responsible for the code hopping algorithm). I would like this source to be switched with the cars ignition. Where can I tap into this feed under the dash?

Now, how much current do I need to supply the remote. I have read about Modifry's 3volt mod and am willing to do this, but am just concerned that it will provide too much current for the remote and cause something to fry. What are everyone's thoughts?

Now for the 2 switched buttons, the power comes from the battery and then is sent through a resistor that is tan in colour with one black stripe around it. Honestly, it has been years since I knew how to read resistors, can someone tell me how much resistance this is?

After the resistor, the power breaks into three and enters the positive terminal of the switches.

So, what I am thinking of doing is taking the +ve 12v of the top cruise button, having it go through Modifry's voltage stepping mod, including the added resistance of the black banded resistor, and then to the negative terminal of the switch.

I will be doing the same for the bottom button of the cruise control onto the -ve of switch 2.

Then I'm going to wrap the whole thing up in a nice little project box and shove it under my dash.

So, in conclusion, I would have 3 voltage stepping circuits.

- One to constantly power the opener.
- One to activate my garage door.
- One to activate the other door.

The bottom two will be Modifry's voltage stepping circuit plus the extra black banded resistance.

Any thoughts on this?

Does the remote always need power? I don't believe so. Is there a better way of doing this?

Thanks guys!

cyberhide

You dont need to use the switches at all on your remote, since you arent using them to activate it.

You can get ignition-controled power from the fuse panel. There are 3 male spade connectors along the left side. The bottom one is ignition controlled.

Also.. how are you sure about the 3v requirement for the remote. What voltage is the battery supplying? You can use a resistor or voltage regulator to control this if need be.

It sounds like that resister is a 0 ohm resister, basically a diode if I remember correctly.

I would wire the tapped source (the cruise control buttons) directly into the pins on the opposite side of our switches on the remote. Basically, when you hit your cruise control button (ie: resume), you will feed power directly pass the switch into the circuit.. activating it.

Basically.. ignore the switches you have on the remote, and use the cruise button as your switches to activate the circuit. Just remmeber to connect the negative terminal of your battery lead on the remote to ground. Also use resisters in your individual circuits to control voltage/etc.

Create as simple a circuit as possible, and things should be fine.

-Chris

S2kRob

I should have explained myself a little better in my first post.

First off, the remote is a 3v unit because it is powered by a 3v lithium battery.

Second off, I will be wiring the negative terminal of switch 1 to the positive terminal of the cruise control. The circuit will need the voltage stepped down from 12v to 3v.

I will be repeating the above for the second switch.

However, other parts of the circuit draw power from the battery directly. IE the code hopping chip. This is the part of the circuit that I am confused about. I believe that this will either need a switched source or maybe potentially a constant power source for the chip to "remember" the codes, but I don't believe this is the case.

My main concern is the amount of current going through the circuit. Does Modifry's voltage stepper account for the current? How do I know what is the proper amount to send through the circuit of the opener?

Thanks for the help!

Rob

S2kRob

edited

modifry

The resistor with a single black stripe is indeed 0 ohms, in other words, it's a jumper. They used a resistor-shaped device so it could be inserted automatically by a machine.

I believe the code-hopping remotes keep their memory even with power removed. I'm not positive, but it seems to me that they must get some kind of feedback from the garage opener telling them to "hop", otherwise, if you pressed the button on the remote when you were out of range the remote would change codes but the opener wouldn't know it.

On the voltge/current issue, I assume you're referring to the info on my web page about using a 3-terminal regulator to power the remote, which you definitely should use since you have a 3v remote. Using a simple resistor will lower the voltage by different amounts depending on whether the remote is transmiting or not, which you don't want to happen. The regulator regulates the voltage under all circumstances, but not the current. The load you attach (the remote) controls how much current is drawn, and since it's designed for 3v, as long as you provide it 3v the current will be correct.

This is one of the "basics" of electricity and electronics that can be confusing to those new to the field. Power sources will generaly have voltage, current, and sometimes wattage ratings, but these are not what always comes out of the supply. The voltage rating is the "nominal" voltage available under normal circumstances. The current and wattage ratings are the MAXIMUM amounts the supply can provide without being overloaded and blowing a fuse or shutting down, but the ACTUAL current is determined by the LOAD, not by the supply.

Think about this - your house power outlets are all 120volts and 15 amps. Does that mean each device you plug in draws 15 amps? No, it only draws what it's rated for. If it has a high resistance it draws very little current (nite light), low resistance means it will draw more current (electric iron).

.

S2kRob

Modifry,

Thanks so much for the refresher course on current in a circuit. I completely forgot it!!

I have the battery out of the remote and will reinsert it and see if it works. I am betting it will.

I'm off to Radio Shack to get all the parts you mention on your webpage.

And yes, it is a 0 ohm resistor, being used to cross one circuit over another.

Can't wait to get this project under way!

S2kRob

Okay, went to the electronics store at lunch and got my bag of goodies!

One final question. Are 1/4 watt resistors enough for this circuit or should I have gotten 1/2 watters.

I have no idea what the current is like through this thing, but I'm guessing it's minimal.

S2kRob

Hey guys, just for future reference on this, the part numbers call for 1/2 watt resistors, so I'm going to have to swap them.