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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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In search of a meter movement
Long time since I've posted on Usenet.
What I want to do is give some public address system operators (in a hotel actually), a clear and easy visualisation of just how loud they have got things running. A VU meter situation. What they should be able to do is see, from a distance, a meter which preferably will have a 270 degree travel arm Small meters just won't cut the mustard. Ideally, too, I envisage driving the meter from the amp speaker supply so that's why I'm not employing electronic level display systems. Trying to keep things as simple as possible. It occurs to me that what I really should use is something like a car's tachometer movement. I know modern units have internal electronics etc. They would be un-necessary and unusable so I'd be stripping them out. In general, what are the movements? Still D'asonval ? What sort of FS sensitivity - 1 mA FS? Anyone played with these things? Thanks. |
#2
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In search of a meter movement
On Mon, 29 Oct 2012 15:07:59 +1100, Black Iccy
wrote: Long time since I've posted on Usenet. Contrary to rumors to the contrary, Usenet is alive and well. What I want to do is give some public address system operators (in a hotel actually), a clear and easy visualisation of just how loud they have got things running. A VU meter situation. What they should be able to do is see, from a distance, a meter which preferably will have a 270 degree travel arm What distance? Small meters just won't cut the mustard. Ideally, too, I envisage driving the meter from the amp speaker supply so that's why I'm not employing electronic level display systems. Trying to keep things as simple as possible. I used to deal with theater applause meters in the 1960's. Something like this, but not quite so big (and ugly): http://en.wikipedia.org/wiki/Clap-o-meter http://blog.eastmanhouse.org/wp-content/uploads/2009/09/Clap-o-meter.jpg They were huge meters, about 4x6ft large, with an indicator arm that probably weighted several pounds. The devices didn't use a standard meter movement. It used a geared motor fighting a spiral spring. The more power applied to the motor, the more it would compress the spring and move indicator. The motor would complain, sometimes get hot, but since the applause was not continuously present, it had time to cool down. It occurs to me that what I really should use is something like a car's tachometer movement. I know modern units have internal electronics etc. They would be un-necessary and unusable so I'd be stripping them out. Most cheap automotive gauges are thermal gauges. That provides damping and vibration proofing. They're also dirt cheap. Tachometers that need to move rapidly use a taut band variation on the D'Arsonval meter. A jeweled bearing D'Arsonval movement wouldn't last a month in a vehicle. In general, what are the movements? Still D'asonval ? In some places, but not all. D'Arsonval, taut band, thermal (bimetallic), electrodynamic, moving vane, thermocouple, piezo, etc. http://gactaern.org/Unit%20Plan/Transportation/Electrical_Electronic_Systems_Design/ESD_7_Non_Electronic_Guage_Indicators.PPT What sort of FS sensitivity - 1 mA FS? 50ua FS for the better meters. Moving mirror galvanometers will to maybe 5ua full scale. Anyone played with these things? Yep. I even got paid to play with them. Maybe if you supplied some numbers (i.e. distance, size, cost, etc), it might be possible to offer some sane suggestions? Ok, enough nonsense. I have two suggestions: 1. Use a virtual meter. Yes, it requires a computah and LCD screen, but those are quite common and amazingly cheap. You can also do it with a SBC (single board computer). On the LCD screen is your meter. The audio goes into the sound card of the computah. If you need a monster meter, use a projection display. If an LCD screen is big enough, commandeer a hotel TV set. http://www.sermonvideos.com/FileCloseup.html?&ID=26107 http://www.theapplausemeter.com 2. Use a moving mirror. The deflection of the mirror will move a reflected light beam across the wall or ceiling. The amount of movement is proportional to the amplitude. The major problem will be damping the mirror so that it doesn't "ring" or move like sludge. I doubt if you can find a large enough panel meter to be seen clearly across a room. I have several pieces of antique test equipment with maybe 12" meters. That's about as big as they get. The problem is that the indicator arm is rather thin and light by necessity, and therefore difficult to see. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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In search of a meter movement
On 10/28/2012 9:07 PM, Black Iccy wrote:
Long time since I've posted on Usenet. What I want to do is give some public address system operators (in a hotel actually), a clear and easy visualisation of just how loud they have got things running. A VU meter situation. What they should be able to do is see, from a distance, a meter which preferably will have a 270 degree travel arm Small meters just won't cut the mustard. Ideally, too, I envisage driving the meter from the amp speaker supply so that's why I'm not employing electronic level display systems. Trying to keep things as simple as possible. It occurs to me that what I really should use is something like a car's tachometer movement. I know modern units have internal electronics etc. They would be un-necessary and unusable so I'd be stripping them out. In general, what are the movements? Still D'asonval ? What sort of FS sensitivity - 1 mA FS? Anyone played with these things? Thanks. I built an LED VU meter years ago. Like 5 green LED's, followed by 2 yellow LED's, followed by 3 red LED's, with them lighting sequentially with volume level, green to red, fluctuating with the level. Theoretically, one of these could be any size you want. I'm sure if you do some searching on LED VU meters, you'll find something. Dan |
#4
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In search of a meter movement
On Sun, 28 Oct 2012 22:10:53 -0700, D wrote:
I built an LED VU meter years ago. Like 5 green LED's, followed by 2 yellow LED's, followed by 3 red LED's, with them lighting sequentially with volume level, green to red, fluctuating with the level. Theoretically, one of these could be any size you want. I'm sure if you do some searching on LED VU meters, you'll find something. That would be an LM3916 IC: http://www.ti.com/lit/ds/symlink/lm3916.pdf https://www.google.com/search?q=lm3916+vu+meter&tbm=isch -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#5
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In search of a meter movement
On Mon, 29 Oct 2012 15:07:59 +1100, Black Iccy
wrote: What they should be able to do is see, from a distance, a meter which preferably will have a 270 degree travel arm Dual LCD VU meters: http://www.sparkfun.com/tutorials/120 http://www.youtube.com/watch?v=jxwFfjCVMII The LCD meters are 4x5" and $50/ea. https://www.sparkfun.com/products/8799 Probably not big enough to see across a room, but still interesting. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#6
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In search of a meter movement
On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann wrote:
https://www.sparkfun.com/products/8799 Probably not big enough to see across a room, but still interesting. I hear you Jeff. I know the LM dot/bar chips too. All these things require another power supply to run them. I'm after something "self-propelled" . The ideal situation is to take the 200 W, Step it up to 1,000,000 V and use the spearing arc to get the barman to turn things down a notch. Reverting: Just looking at some E-diagrams for these car tacho's, some seem to have a double winding as a designate sine/cosine measurement from the chips. This implies we are still ultimately at an analog system. |
#7
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In search of a meter movement
On Sun, 28 Oct 2012 21:51:17 -0700, Jeff Liebermann wrote:
What distance? Oh, as far as a deaf and blind barman can manage. About 10 ft max -) It would be within the bar area domain i.e. not for customer viewing. and move indicator. The motor would complain, sometimes get hot, but since the applause was not continuously present, it had time to cool down. Motorised is a slight overkill -) I'm thinking of using the Pwr-Amp output suitably rectified and damped. Yep. I even got paid to play with them. Maybe if you supplied some numbers (i.e. distance, size, cost, etc), it might be possible to offer some sane suggestions? Pretty much car dashboard size will be OK. Perhaps no more than 3" dia. They can occasionally wander over to inspect the audio level after being beaten by a whip (if they ever cared enough) 2. Use a moving mirror. The deflection of the mirror will move a reflected light beam across the wall or ceiling. The amount of movement is proportional to the amplitude. The major problem will be damping the mirror so that it doesn't "ring" or move like sludge. No, no, no. Its a pub not a disco. -) |
#8
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In search of a meter movement
On Sun, 28 Oct 2012 22:10:53 -0700, D wrote:
I built an LED VU meter years ago. Like 5 green LED's, followed by 2 yellow LED's, followed by 3 red LED's, with them lighting sequentially with volume level, green to red, fluctuating with the level. Theoretically, one of these could be any size you want. I'm sure if you do some searching on LED VU meters, you'll find something. Yep. There are kits out there and I could do the same. Two (three ?) things working against that. 1. Keeping a constant E/I supply to the displaying/sensing device which would probably be needed at low power levels. Easy to drain a watt or less at hi-levels (max 200 power amp) 2. Lights get 'missed' in a well lit area. 3. Cost. They won't come at things that cost money (gee. surprise). |
#9
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In search of a meter movement
Black Iccy wrote in message
... On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann wrote: https://www.sparkfun.com/products/8799 Probably not big enough to see across a room, but still interesting. I hear you Jeff. I know the LM dot/bar chips too. All these things require another power supply to run them. I'm after something "self-propelled" . The ideal situation is to take the 200 W, Step it up to 1,000,000 V and use the spearing arc to get the barman to turn things down a notch. Reverting: Just looking at some E-diagrams for these car tacho's, some seem to have a double winding as a designate sine/cosine measurement from the chips. This implies we are still ultimately at an analog system. A rechargeable with bridge rectifier and some kohmish droppers from the speaker line? kohm values from some knowledge of what the pub's normal audio power throughput is |
#10
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In search of a meter movement
When the team hits on a device , my pub could do with one. Amp and controls
in a sideroom with not even a monitor speaker in that room. Why is it beyond management to put stickers on the volume control scale with numbers of people in the bar comensurate with speaker audio levels and not the usual meaningless 0 to 10 numbers. |
#11
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In search of a meter movement
Black Iccy wrote:
On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann wrote: https://www.sparkfun.com/products/8799 Probably not big enough to see across a room, but still interesting. I hear you Jeff. I know the LM dot/bar chips too. All these things require another power supply to run them. I'm after something "self-propelled" . The ideal situation is to take the 200 W, Step it up to 1,000,000 V and use the spearing arc to get the barman to turn things down a notch. Reverting: Just looking at some E-diagrams for these car tacho's, some seem to have a double winding as a designate sine/cosine measurement from the chips. This implies we are still ultimately at an analog system. step up transformer of some kind? Jamie |
#12
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In search of a meter movement
On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy
wrote: Oh, as far as a deaf and blind barman can manage. About 10 ft max -) It would be within the bar area domain i.e. not for customer viewing. Make it big and easily visible and you have a way of keeping the noise level down in the bar. Calibrate it in SPL units and label it from whisper to threshold of pain. I just hate shouting over the music and the crowd. You could also program in an upper limit threshold switch. When the bar noise level reaches the equivalent of a jet engine on takeoff, it automatically turns off the music and the house lights. Claim it's a power failure if anyone asks. The noise will subside as everyone looks around for what happened. A few seconds later, the power comes back on and life continues as before. Do it often enough, and the crowd will be trained not to yell so much. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#13
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In search of a meter movement
On 10/29/2012 9:23 AM, Jeff Liebermann wrote:
On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy wrote: Oh, as far as a deaf and blind barman can manage. About 10 ft max -) It would be within the bar area domain i.e. not for customer viewing. Make it big and easily visible and you have a way of keeping the noise level down in the bar. Calibrate it in SPL units and label it from whisper to threshold of pain. I just hate shouting over the music and the crowd. You could also program in an upper limit threshold switch. When the bar noise level reaches the equivalent of a jet engine on takeoff, it automatically turns off the music and the house lights. That's an extremely BAD suggestion. First thing that's gonna happen is that the lawyers will descend on him with injury lawsuits and he'll be out of a bar. Claim it's a power failure if anyone asks. The noise will subside as everyone looks around for what happened. A few seconds later, the power comes back on and life continues as before. Do it often enough, and the crowd will be trained not to yell so much. |
#14
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In search of a meter movement
On Oct 29, 11:23*am, Jeff Liebermann wrote:
On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy wrote: Oh, as far as a deaf and blind barman can manage. About 10 ft max -) It would be within the bar area domain i.e. not for customer viewing. Make it big and easily visible and you have a way of keeping the noise level down in the bar. *Calibrate it in SPL units and label it from whisper to threshold of pain. *I just hate shouting over the music and the crowd. You could also program in an upper limit threshold switch. *When the bar noise level reaches the equivalent of a jet engine on takeoff, it automatically turns off the music and the house lights. *Claim it's a power failure if anyone asks. *The noise will subside as everyone looks around for what happened. *A few seconds later, the power comes back on and life continues as before. *Do it often enough, and the crowd will be trained not to yell so much. -- Jeff Liebermann * * 150 Felker St #D * *http://www.LearnByDestroying.com Santa Cruz CA 95060http://802.11junk.com Skype: JeffLiebermann * * AE6KS * *831-336-2558begin_of_the_skype_highlighting*FREE*831-336-2558 LOL |
#15
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In search of a meter movement
Black Iccy wrote: On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann wrote: https://www.sparkfun.com/products/8799 Probably not big enough to see across a room, but still interesting. I hear you Jeff. I know the LM dot/bar chips too. All these things require another power supply to run them. I'm after something "self-propelled" . The ideal situation is to take the 200 W, Step it up to 1,000,000 V and use the spearing arc to get the barman to turn things down a notch. Reverting: Just looking at some E-diagrams for these car tacho's, some seem to have a double winding as a designate sine/cosine measurement from the chips. This implies we are still ultimately at an analog system. GM used to use balanced movements in gauges like that. DC on one coil, signal on the other. That allowed them to stay accurate, even with a low battery. I am building a LCD level meter, and when the signal gets too high it will cause the monitor output to clip. The same circuit could be used to drive the main amp. Another approach would be to use the last two levels to reduce the amp output by 6 or 12 dB, so if it's dropping as they turn it up (or clipping if they are on the edge) they will back it off. |
#16
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In search of a meter movement
On Mon, 29 Oct 2012 09:23:54 -0700, Jeff Liebermann wrote:
When the bar noise level reaches the equivalent of a jet engine on takeoff it automatically turns off the music and the house lights. Already got that facility. It's called thermal overload protection system. It works too. Amazing the panic it causes when there's silence and they find they don't uderstand the problem and where it lies -) |
#17
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In search of a meter movement
On Mon, 29 Oct 2012 10:40:12 -0500, Jamie
t wrote: step up transformer of some kind? Jamie No. Doubt it. This is the sort of thing I'm stumbling across. http://www.datasheetcatalog.org/data...r/CS8191-D.PDF Sort of implies a highly idiosyncratic measurement system and, at the least, a specialised meter movement. |
#18
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In search of a meter movement
On Mon, 29 Oct 2012 09:40:19 -0700, mike wrote:
On 10/29/2012 9:23 AM, Jeff Liebermann wrote: On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy wrote: Oh, as far as a deaf and blind barman can manage. About 10 ft max -) It would be within the bar area domain i.e. not for customer viewing. Make it big and easily visible and you have a way of keeping the noise level down in the bar. Calibrate it in SPL units and label it from whisper to threshold of pain. I just hate shouting over the music and the crowd. You could also program in an upper limit threshold switch. When the bar noise level reaches the equivalent of a jet engine on takeoff, it automatically turns off the music and the house lights. That's an extremely BAD suggestion. First thing that's gonna happen is that the lawyers will descend on him with injury lawsuits and he'll be out of a bar. Oh, you're no fun. If it turns into a litigatory exercise, just tell the judge that the music system blew the circuit breaker and that it took a few seconds/minutes to reset it. It's always best to have plausible denial prepared before doing anything risky. However, it is possible that some patron in the noisy bar will complain from hearing damage. To prepare for that litigatory event, the bar should place signs indicating: "Yelling above 90dB (0.1Pa) prohibited" along with SPL bar chart and OSHA web site URL. If someone claims that their hearing was damaged, and that the bar did not take sufficient precautions to prevent hearing damage, then the sign should provide sufficient evidence of informed consent by the patrons to be bombarded with high noise levels. As an extra bonus, it might be useful too record the sound levels on a strip chart recorder for later use as evidence. Claim it's a power failure if anyone asks. The noise will subside as everyone looks around for what happened. A few seconds later, the power comes back on and life continues as before. Do it often enough, and the crowd will be trained not to yell so much. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#19
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In search of a meter movement
On Mon, 29 Oct 2012 17:43:23 +1100, Black Iccy
wrote: On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann wrote: https://www.sparkfun.com/products/8799 Probably not big enough to see across a room, but still interesting. I hear you Jeff. I know the LM dot/bar chips too. Here's a kit, ready to play: http://www.mcmelectronics.com/product/CEBEK-VM-22-/28-22942 All these things require another power supply to run them. I'm after something "self-propelled" . You have heard of batteries? The problem is lighting up a mess of LED's is going to burn some power. If you must, point some solar cells at the room lighting and use that to charge the battery. Oh wait, it's a bar, where the lights are always dim. Ok, all mechanical and no electronics. Take a large ring with a diaphragm stretched across the ring. Find a mechanical barometer and tear it apart. Remove the pressure chamber and connect the actuator arm to the center of the large drum. Add a bit of fluid damping by submerging the mechanism in thin oil (5-10wt). When the sound pressure in the room moves the drum slightly, the barometer mechanism will indicate the peaks. Patent pending... The ideal situation is to take the 200 W, Step it up to 1,000,000 V and use the spearing arc to get the barman to turn things down a notch. Reverting: Just looking at some E-diagrams for these car tacho's, some seem to have a double winding as a designate sine/cosine measurement from the chips. This implies we are still ultimately at an analog system. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#20
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In search of a meter movement
On Tue, 30 Oct 2012 10:25:09 -0700, Jeff Liebermann wrote:
Ok, all mechanical and no electronics. Take a large ring with a diaphragm stretched across the ring. Find a mechanical barometer and tear it apart. Remove the pressure chamber and connect the actuator arm to the center of the large drum. Add a bit of fluid damping by submerging the mechanism in thin oil (5-10wt). When the sound pressure in the room moves the drum slightly, the barometer mechanism will indicate the peaks. Patent pending... Snaps fingers. That's it. Sheer genius! A single 2" loudspeaker clamped to the back of a barometer. Speaker cone has a pressure valve fitted. |
#21
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In search of a meter movement
On Mon, 29 Oct 2012 15:07:59 +1100, Black Iccy
wrote: Long time since I've posted on Usenet. What I want to do is give some public address system operators (in a hotel actually), a clear and easy visualisation of just how loud they have got things running. A VU meter situation. What they should be able to do is see, from a distance, a meter which preferably will have a 270 degree travel arm Small meters just won't cut the mustard. Ideally, too, I envisage driving the meter from the amp speaker supply so that's why I'm not employing electronic level display systems. Trying to keep things as simple as possible. It occurs to me that what I really should use is something like a car's tachometer movement. I know modern units have internal electronics etc. They would be un-necessary and unusable so I'd be stripping them out. In general, what are the movements? Still D'asonval ? What sort of FS sensitivity - 1 mA FS? Anyone played with these things? Thanks. Hmmm. Off the top, an ordinary (wide pointer?) meter with a video cam hooked up to a 17 inch monitor. I doubt that the hotel staff would recognize proper VU ballistics. ?-) |
#22
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In search of a meter movement
On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann
wrote: On Mon, 29 Oct 2012 15:07:59 +1100, Black Iccy wrote: What they should be able to do is see, from a distance, a meter which preferably will have a 270 degree travel arm 1024 LED VU meter: http://vimeo.com/44248192 Kinda like a light show. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#23
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In search of a meter movement
On Wed, 31 Oct 2012 19:07:42 -0700, Jeff Liebermann wrote:
1024 LED VU meter: http://vimeo.com/44248192 Kinda like a light show. Kinda attractive but it would make my Cherry-brandy, at the bar, a little black looking wouldn't it? I wonder where GreenXenon got to -) |
#24
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In search of a meter movement
On Thu, 01 Nov 2012 17:22:31 +1100, Black Iccy
wrote: On Wed, 31 Oct 2012 19:07:42 -0700, Jeff Liebermann wrote: 1024 LED VU meter: http://vimeo.com/44248192 Kinda like a light show. Kinda attractive but it would make my Cherry-brandy, at the bar, a little black looking wouldn't it? Black is the current high fashion color. The Darth Vader and Gothic looks are back. Notice how HP printers went from all off-white, to all black. Black is cool. I wonder where GreenXenon got to -) I think (not sure) that he's morphed into "Skybuck Flying". Same dumb questions, bad physics, bizarre logic, and chronic computer problems. I doubt that there could be two different humans with exactly the same bad habits, strange personalities, and bad luck. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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