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Hello everyone, I've been thinking for a while that I'd like to clean up my computer's power wiring... I know the usual methods of using loom, etc, and tying them out of the way, but what I'd like to do is make a box for each 3rd of my server case with one power in connector and 3 - 4 power out connectors. I realize the number one issue would be pulling too much power through too small of gauge wire, but would I also do well to put in some high capacity caps on each rail in each box? To act as a kind of buffer? Thanks.

Well, after talking to my friend who asked about doing this, he's taken some time to think about it and decided to do the sensible thing..... buy a case big enough to fit a full ATX PSU.... Still, one of these days I might be inclined to experiment on this with a couple cheapie's.... just to find out what works best. ;) Thanks alot guys!

:-\ whoa..... umm, yeah what that other guy said. :o Err, ok, well backing up a few posts, I'm sure the two 9v's in serial didn't fry the cap as I hadn't even used them when that prob occured. It may have fried one of the IC's granted, but as I said, I tested the voltages and they were putting out only about 15v combined, but admittedly I tested them without a load. I think it's more likely that I miplaced a jumper.... I tend to do that.... fortunately enough I only tend to do it on the first circuit and not any to follow. :P I'm gonna go through and trace the circuit tomorrow.... hopefully it is just a misplaced lead and not a fried IC or two. I am interested in the complementary pair suggestion though, if the output is higher it should be exactly what I'm looking for. One of these days I need to either find out how to read and understand the values of transformers that I've found at suppliers'..... or learn how to start wrapping them myself. At any rate thanks! and I'll be sure to post once I get this initial one debugged.

Well, I had it running fine on my breadboard.... I think I burned one of the ICs..... seres me right for not keeping enough IC Sockets on hand. I was wondering, if I use a larger bypass cap will it reduce battery life?

Good to know, AudioGuru, so would one of the other opamps I listed as having on hand work better than a 741? The 741 seems to run fine... but I haven't tried a different one... all my others are dual or quad.

Ok, so far, so good (excellent actually ;D).... Now, how about an auto reset on the trigger? I imagine I could accomplish it myself using an opamp/comparator, but can it be done using fewer parts such as a transistor in combination with another cap and pullup resistor? Something which'll reset the trigger once the voltage across the two contacts returns to 0v or possibly once the resistance becomes great enough for it not to trigger the alarm.

It was definitely shorted.... because the 555 was still getting the trigger pulses. That's pretty muvh how I thought it was working, but

Horay! Well, I swapped the ceramic cap I had in there (I wasn't positive of the value) and put in a 10nf Met. Poly. with the second pull up resistor and it works like a charm! I understand the basics of most parts of this circuit, but the cap and pullups escape me... I kinda see some of the picture, but I'm not understanding the whole thing... care to break it down for this nooB?

Hmmm...... not sure what I've done wrong, but if I keep the trigger grounded the circuit doesn't stop until the trigger is pulled from ground. I understand somewhat what you're saying about the op-amp, but as i said, right now 741's, 324's, 348's, and 1458's are all I have to work with.... the 741 being the only single. I went ahead and tried 2 9v batteries in series and got buetter volume results. I guess the thing which is on my priority list is the triggering. I need to find where I made the mistake that's keeping the trigger active beyond the specified time period.

Hey, wow, talk about a quick response... As a matter of fact I am using a 741.... didn't have any other type of single op-amp on hand. So as for volume, I'm either being limited by the piezo element or the single 9v supply... right? I mean, it's loud right now as long as the freq. is perfectly tuned, but I don't wan't loud..... I want downright terrifying!!!!!! ;D No, I'm not looking for ear damaging volumes either, but given that treble is directional I want to make sure my dogs hear it clear as day even though it's sitting on top of the refridgerator (of doom!). You know what I mean?

I keep getting this error whenever I try to use the spellcheck.

Okay, I've built the circuit and it works well, I'll need to modify the trigger a bit, either a one-shot circuit or a long delay before resetting as the contacts may take a while to dry and stop conducting (if I'm not home). Also, am I correct in thinking that the gain is set by the 10K resistor between the op-amp's output and the inverting input? Not that I'm likely to get much more out of it while running on a battery. I did replace the 22K resistor in the R/C with a 100K pot... makes it alot easier to find the piezo's "sweet spot". Thanks a ton Alun and everyone. Do you guys think adding another 555 timer running astable would work alright if set with a cycle of something along the lines of: 5 sec. high, 10 min. low? I don't think it would work well, but if it's only gonna loose some precision I might be able to deal with it. If not, can anyone offer another suggestion?

LOL... ;D Oh I've been there a few times.... then again I'm still a newbie.... but even I know that once I've "Mastered" something I'll always find more to learn. Thanks for going to the trouble Alun, I'll probably have time to breadboard this tonight. I'll post my results... well, I'll post whether it works or not... as for actual results... depends on my doggy. ;)

Hey guys, thanks for all the responses. For the time being I've set up a small analog buzzer from RatShack which made for some VERY amusing moments last night.... so funny, so sad.... poor startled little doggy..... so funny!I think I'll give Alun's circuit a shot, but I was wondering if I could substitute the CA3130 with another op amp such as a LM740 or a LM1458? These I have on hand. :D

I presume, this is for some sort of medicinal use? In which case the frequency probably needs to be quite accurate... do you know the frequency needed? As for the circuit, if the use of this appliance is going to be tethered to the computer via the wiring anyway, why not box the driver and just run the transducer out on a longer wire?