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I personally would recommend against a switch dependant on the garage door opener's operation. I would recomment placing something along the lines of 6" to 12" of strip magnet on the door and a reed switch on the inside frame. This way if someone were to pull the release and open the door bypassing the opener you would still know the actual state of the door. I've worked on similar issues before where a keypad was placed outside to open the garage without key or remote and if for any reason they got out of sync you'd end up having to type in your code to close the door but pressing one button would open it...

Hi everyone, I was just curious, mac72, what type of LM317 have you got (I'm referring to the package)? If you don't mind the brand and suffix would help as well. Thanks.

well, if a few other want to verify the design I'll give it a shot on my backup PC.... I'll also need to know where to get software for SuSe Linux though. I'm not trying anything untested on my main PC. Theory is one thing.... I've had a lot of them.... ;D The product can sometimes be quite different, trust me. :-[ But yeah if someone else would please look this over and verify whether it's safe for use (at least with low voltage circuits 1-18v) I'll give it a try and post my results. But if you're working on something better..... well. ;)

Woohooo..... Somewhere I can help! As Yevgeni mentioned another name for an opto coupler is a phototransistor, it's a type of optoisolator. In a lot of cases I've found the 4N25 to be sufficient for my needs. What we need to know is how many LEDs and their specs. You might need to use the output of the optoisolator (call it whichever you like) to control a transistor with a higher current rating. The switch is pretty simple there are a couple ways to take care of your needs there too. But we'll worry about that once you supply us with some more specifics. As for controlling your pumps, if you are certain they'll operate at a lower voltage, it shouldn't be too difficult to make a coltroller using a LM317 voltage regulator just so long as it's one which'll handle 1.5A. But, like I said, first things first, how about some data on how many LEDs and their requirements. (If I'm wrong on any of this someone please feel free to educate me)

Well, the tape option would work, but wouldn't that require a LOT more in the way of components, space and overall power? A COB might not be a bad idea but I couldn't begin to tell you where to go to get that designed, much less produced cheaply... Unless you're planning a full production run, in which case I'd still probably prototype the first couple using ISD chips, then go with COB when you can afford to hire out for it.... as far as I know it's nothing most people (even hobbyists) could design much less make from home.

You know oddly enough I have yet to burn a transistor out... :o As for the LEDs well, that's what I get for not paying enough attention. Thanks for all the suggestions Audioguru, and I look forward to more on that circuit of yours. I was interested in doing something similar using a 3 LED IC I found online.... ordered 2. ;) They're not ultrabright by any stretch but I think they'll be fun to tinker with.

Yup, I saw the "mood light" ;) I'm familiar with basic concept, I've made a couple circuits that'll fade an LED using a dual or quad opamp, but what I want is to fade 3 or more in sequence. I'll try out the cap and transistor when I get the parts. This circuit would most likely be used for lighting effect inside a PC so a supply voltage of 12 and lower isn't a problem. And yes, red LEDs of medium intensity.... they're cheaper than the 1.9v red ones I've got set aside for finished projects. ::) Kinda got tired of blowin' pricey LEDs (It really only happened twice). Thanks!

Is an optoisolator out of the question? I figure you'd need to add some sort of control to adjust the gain on the transistor side of it and how about the sensors? Do they have to supply any voltage or signal or is everything supplied by the test circuit? In which case you really just need to make sure that signal is attenuated enough for the emitter side to handle. But are optoisolators responsive enough?

Thanks for the reply Audioguru, I don't have all the parts to experiment with yet (gotta order some more LEDs). I'm ordering from DigiKey and they list two "series" of 4046; CD4046*, and 74HC4046* does it matter which one I use? Now back to the fading, how do I go about using a cap to produce a fade on and fade off effect? More specifically, if I'm using an NPN transistor, between where do I connect the cap? I could imagine it going from base to collector, or from base or emitter to ground (although I suspect that'd require a larger cap). What's most efficient? Thanks again. EDIT: Oh, BTW the voltages I referred to at the start of this thread were merely for example... the LED's I'm ordering are 2.2v (2.4max) @ 20mA (40mA max)... Although I suspect that a transistor may still be needed to efficiently fade the LEDs on and off.

Thanks for the reply Dazza but the link's either broken or the server's down... I'll try it again tonight. Although I really don't think I need anything very complex, just a small circuit to isolate the soundcard/PC from the test circuit. I'm too new to oscilloscopes to know what can and can't be done in order to keep a clean signal, so if anyone else has a schematic it'd be deeply appreciated. I think this is what the initial poster HelpMe wanted as well. Thanks! ;D

I'm also interested in making one of these, but out of fear of frying my soundcard I'm hesitant. Does anyone possibly have a schematic for one which makes the use of an optoisolator? I don't anticipat working on anything which requires more than 18v (for the circuit) that I'd need to test so I think there must be a simple way of making an isolating interface. If someone has a link or schematic it would be much appreciated. ;D Me = newbie :-\ Thanks

Hello, This is something I've been trying to figure out the logic of.... I'm lost. :-\ There are two additions I'd like to make to a LED chaser similar to those which commonly us a 555 and a 4017. The first is I'd like to make one where each LED slowly fades on and then slowly fades off (without using 20 large caps, which I'm not sure would work anyway). So basically I want the power running along a triangle wave as can be managed with a couple op amps so the LED get .2v up to 3.5v back to .2v and off... gradually. I've got it The second part (I should probably focus on one thing at a time) would be to add a variable acceleration to the circuit, so that depending on how a given pot is set the pulse width will span perhaps 1 second peak to peak and gradually move faster with each pass. I'm thinking something along the lines of using a second decade counter with different resistances on the output affecting the primary 555's input... Does that make any sense? I think this would work, but is there an easier way? Thanks, Christoph

The ISD's use non-volatile memory (EEPROM) so all that you would need to do as far as I can tell is connect a mic and record button long enough to record the desired sound.... then remove the two and insulate the record pin to prevent it from grounding. I'm just a newbie with alot of this so if someone with more exxperience would care to verify this I'd appreciate it.

Thanks again Ante, Anyone know of any other values in the E12 (or even E24) range which has two valid codes?

Thanks for the prompt reply Ante. Ok, so there isn't one that's "right" or "standard"? Has anyone here come across either or both? (I'm making a chart and labels for my organizer... ;) )

Ok, I know this is an old thread but it seems the best place for my question instead of starting a new thread.... What's the proper color code for a 1 Ohm resistor? Black, Brown, Black or Brown, Black, Gold?

I you look here on page 2 you'll see a pic os a single vs a dual-gang pot. I've only ever seen multiple-gang pots in similar packages where it's essentially 2 or 3 pots in one case with the wipers all connected to a common axle. Yes this can cause minor variances between the two "networks" when one's 68/32 the other might be 60/40... yeah this can case a problem if the circuit it's being used in isn't calibrated to account for this. That's not my issue at present though... I'm looking to avoid ganged pots all together. Especially since I've never seen a 6-gang pot. If you want to look at it in regards to a variable resistor network, that's fine... can I use a variable resistor network to control a series of transistors which are each operating on their own circuit? EDIT: That is, can I use a potentiometer to control the signal supplied to the base of multiple transistors to allow me to use the transistors as variable resistors?

Hi everyone, I was wondering if it is possible to use transistors connected to one pot to create a multiple channel control.... the use here would be for a 5.1 sound card which only has volume control via software. I thought it might be possible to acheive the same effect as a multi-gang pot through connecting one pot (audio taper) to the base of multiple transistors? The thought is that as the voltage from the pot increases the transistors open up that much more and the volume increases to the same degree accross all 6 channels. Would this work?

Thanks for the reply, I did experiment with dividing the output of the two pots for a mid point but I found that I do prefer the extra control attained by using a pot on the mid vref as well. I think from my experiments today that I may need to actually go with 1K pots, the 10K are just too sensitive for this project (serves me right for using dirt cheap single turn pots). Anyway, The drop from 3 10K pots to 3 1K pots between the +5v and ground won't cause an issue will it? Like I said before, I'm a newbie with only enough knowledge to do damage.... albeit in very interesting ways that my parents never would have imagined. ;D This circuit is rather impractical for what I'm using it for but I set out to do this project using an op amp/comparator do see if I could actually get it running. Well, it works!!!! Now I just need to work the bugs out. And if in the end I end up using something along the lines of a LM3914 well, I'll have a very nice little battery tester! 8)

Hi everyone, First off I love this site! I found it a few days ago and it has been a huge help in creating a circuit I've wanted to build for a while. Here's the situation: I'm building a voltage meter using a LM348 (quad op amp) as a comparator. I have three reference voltages to set. I was originally going to use resistors to divide the voltage but found that usings pots would be much better since I can adjust the references as needed. Now for the questions, I have 2 100K pots rated for .1W, I know the op amp's power requirements are very low so I don't think the small pots will be a problem. I understand that if I wire one leg to ground, the other leg to my PSU's +5v line and use the wiper as output I'll get my divider (so that when centered/balanced the output will be ~2.5v). The first question is do I need to worry about this putting a load on my PSU? You know in a way it can't handle? It's capable of ~40A on the 5v rail. Also, would this be too much for the post to handle? As I understand it the low currentdraw from the op amp's inputs shouldn't pose a problem, but if there is a possibility could I perhaps buffer the pots using a resistor on the wiper or one on each of the main pins? The second part is this, I need three reference points; one high, one mid, and one low. Can I wire the high and low using pots as described above and simply use two equal resistors between the output of both pots to get a consistant mid point? So that if I were to adjust the high vref higher, the midpoint would follow maintaining it's position between the two? If so, does it matter what size resistor? I'm sure it does to a degree but would 1K suffice? Thank you!