I had occasion to run a PCB for a little preamp, going in between whatever media player and a 60 w/ch power amp for a new job site boom box I’m building. Most everything requires stepping through stupid menus with one button or running off an app which will NOT operate with sweaty hands. So front panel controls are called for. Made one almost identical in college (on a home etched PCB - which stained the floor tile yellow in Alpha 236). Kept getting asked “Are you guys building a bomb?” when it was clearly an audio circuit. So this time it got printed right on the board.
Attachments
Ignorance is a terrible thing.
I remember working in a factory in late 1970's.
I really wanted to get into electronics so got loads of electronic books and studied in my breaks at work.
I was asked a few time what I was doing.
After I told them I was told in no uncertain terms I would never get out of the factory and was stuck there for life.
I did get out and passed my electronic exams and was in electronics for 40+ years.
Ignore the idiots.
I remember working in a factory in late 1970's.
I really wanted to get into electronics so got loads of electronic books and studied in my breaks at work.
I was asked a few time what I was doing.
After I told them I was told in no uncertain terms I would never get out of the factory and was stuck there for life.
I did get out and passed my electronic exams and was in electronics for 40+ years.
Ignore the idiots.
Apparently they take a dim view of this sort of thing in airport security...
Many years ago I watched a film based on the theft of the Jules rimet trophy the year England won the world cup. Early in the film a family at Customs in the UK were asked if they had anything to declare. The father joked that they'd got the world cup hidden in the car. Interspersed through the rest of the film were short scenes of an increasingly dismayed family as their car was reduced to component parts in front of them...
It’s easier to get C4 on the street than it is to get power transistors from distributors, these days. After waiting years to get the mosfets for the speaker protect SSRs, and months to get the last batch of MJL21194’s for my production run you think I’d blow it up? If customs had actually opened up the box (and the individual packaging so the word “bomb” can be read) they would have seen this ominous looking thing in there with it. That is very obviously an audio circuit. You’d have to see it to grasp the scale of it. The board is over 18” long. These are just the drill templates, which will also serve as test mules to be sure the last of it is working right. Will be reordered in 2 ounce copper, with the outer semiconductor mounting holes truncated, when I’m sure everything will go together as planned. One more chance to make correction, then carved in stone. Of course there are no components in the box either, just blank boards. So no chance of explosion.
The same group that asked if my tone control board was a “bomb” also got a good look at 50 amps of current going through a 5 gallon bucket of saline, getting the transformer all melty a couple weeks earlier. How I got the electric shock of my life jacking with it is another story. They also saw us testing the “KM441” out in the quad not too long ago either. Being tested without the dim bulb this time, so plugged in and listened to from a distance. It wasn’t trusted yet, considering all the oscillation troubles I had - which ultimately just required “good” decoupling caps, not just ones out of a grab bag.
The same group that asked if my tone control board was a “bomb” also got a good look at 50 amps of current going through a 5 gallon bucket of saline, getting the transformer all melty a couple weeks earlier. How I got the electric shock of my life jacking with it is another story. They also saw us testing the “KM441” out in the quad not too long ago either. Being tested without the dim bulb this time, so plugged in and listened to from a distance. It wasn’t trusted yet, considering all the oscillation troubles I had - which ultimately just required “good” decoupling caps, not just ones out of a grab bag.
Attachments
Bomb, what bomb?
Wind the clock back to about 1976. I had built a "booster" to make the window rattler in my shagged out van a bit louder. This was the 70's, so I used clones of the SWTPC Tiger amp boards mounted inside a typical BUD or Hammond chassis like one would use to make a guitar amp. There were heat sinks mounted around the entire perimeter of the chassis and two large Mallory electrolytic caps held to the top of the thing with fat Ty Raps. It worked, was extremely loud and shook the van quite well thanks to the single Universal Tiger that fed a 15 inch subwoofer under the bed in the back. There were also several smaller amps, one for each speaker. I think they were Plastic Tigers, but I'm not sure now. I had no real ides just how well it really worked though.
With permission and proper paperwork, I brought it into the cal lab at Motorola where I worked and took all the typical audio measurements on it. I worked the evening shift, so there was a change of security guards while I was at work. The guards that were present when I was leaving saw those big caps on the top and decided that I had made a bomb. They were about to call the local cops when I convinced them to call my boss and wake him up at midnight for an explanation. There was one person in the whole building at night who was responsible for making decisions regarding the facility and its operations for the evening shift and he just happened to be leaving. I got his attention and explained it all to him who was well aware of the thunder that came out of my van, so the "bomb threat" was defused. Those guards called me "the terrorist" long before that word had the meaning that it does today.
What exactly is a bomb?
Rewind the clock to 1969. I was in high school. I spent 3 hours a day in a vocational electronics class for two years. Other students were in similar classes from auto shop to metal working to commercial art to cosmetology. There was a long standing rivalry between the electronics guys and the auto shop guys that was going on before I came to the school, and after I left, but only once it escalated to getting the whole school evacuated. Long before the movies, there was a weekly show on TV called Mission Impossible. There Mr. Phelps solved all sorts of impossible tasks some of which involved "bombs." Now the typical bomb seen on TV at the time involved a wind up alarm clock, some batteries, some brown sticks or greenish liquid, and some wire that was always partially coiled up. This was often stuffed into a box that could be placed wherever the bad guy wanted to. So, after trying to take some sort of standardized tests that took a couple hours while breathing fumes from an old Dodge that had been backed up to the hallway and had oil poured into the carburetor while the engine was running, electronics had to retaliate.
Well it seems that gathering up the required implements for something that looked quite a bit like it could have been seen on a recent episode of Mission Imposible and placing them in a shoe box on the teacher's desk with the clock ticking early in the morning got a response from the Dade County Bomb Disposal unit while the whole school stood outside and watched. Those involved threatened each other with a gruesome death if anyone talked.......nobody did.
Wind the clock back to about 1976. I had built a "booster" to make the window rattler in my shagged out van a bit louder. This was the 70's, so I used clones of the SWTPC Tiger amp boards mounted inside a typical BUD or Hammond chassis like one would use to make a guitar amp. There were heat sinks mounted around the entire perimeter of the chassis and two large Mallory electrolytic caps held to the top of the thing with fat Ty Raps. It worked, was extremely loud and shook the van quite well thanks to the single Universal Tiger that fed a 15 inch subwoofer under the bed in the back. There were also several smaller amps, one for each speaker. I think they were Plastic Tigers, but I'm not sure now. I had no real ides just how well it really worked though.
With permission and proper paperwork, I brought it into the cal lab at Motorola where I worked and took all the typical audio measurements on it. I worked the evening shift, so there was a change of security guards while I was at work. The guards that were present when I was leaving saw those big caps on the top and decided that I had made a bomb. They were about to call the local cops when I convinced them to call my boss and wake him up at midnight for an explanation. There was one person in the whole building at night who was responsible for making decisions regarding the facility and its operations for the evening shift and he just happened to be leaving. I got his attention and explained it all to him who was well aware of the thunder that came out of my van, so the "bomb threat" was defused. Those guards called me "the terrorist" long before that word had the meaning that it does today.
What exactly is a bomb?
Rewind the clock to 1969. I was in high school. I spent 3 hours a day in a vocational electronics class for two years. Other students were in similar classes from auto shop to metal working to commercial art to cosmetology. There was a long standing rivalry between the electronics guys and the auto shop guys that was going on before I came to the school, and after I left, but only once it escalated to getting the whole school evacuated. Long before the movies, there was a weekly show on TV called Mission Impossible. There Mr. Phelps solved all sorts of impossible tasks some of which involved "bombs." Now the typical bomb seen on TV at the time involved a wind up alarm clock, some batteries, some brown sticks or greenish liquid, and some wire that was always partially coiled up. This was often stuffed into a box that could be placed wherever the bad guy wanted to. So, after trying to take some sort of standardized tests that took a couple hours while breathing fumes from an old Dodge that had been backed up to the hallway and had oil poured into the carburetor while the engine was running, electronics had to retaliate.
Well it seems that gathering up the required implements for something that looked quite a bit like it could have been seen on a recent episode of Mission Imposible and placing them in a shoe box on the teacher's desk with the clock ticking early in the morning got a response from the Dade County Bomb Disposal unit while the whole school stood outside and watched. Those involved threatened each other with a gruesome death if anyone talked.......nobody did.
^ LOL did the same thing to the grumpy old lady down the block with flares electrical tape a battery and an alarm clock. It was funny until the bomb squad arrived and evacuated the houses near hers. We watched from the bushes and never said a word after. Later we graduated to making our own "firecrackers" from powdered model rocket engines and various containers. We eventually tried to scare the patrons of the local bar with a new design made in an empty CO2 container. Blew the back door off of the bar with that stunt. We were good troublemakers though, never talked and never got caught.
About 15 years ago I had a very odd experience with a certain very large distributor of electronics components. The sales department actually called me and starting asking questions about who I was and what I was going to do with the parts. I explained that I am an electrical engineer with a regular EE day job and a part time audio hobbyist designing & building audio hardware for fun. There was a lot of unusual paperwork I was required to fill out in order to have my account reinstated. I have a pretty good idea what it was about, but am still puzzled as to what triggered the concern.
This hasn't happened with any other supplier.
Last year for a while I did notice that DHL packages from JLCPCB seemed to be hung up in customs for an uncharacteristically long time and some packages were opened, and then it just stopped and things returned to normal.
This hasn't happened with any other supplier.
Last year for a while I did notice that DHL packages from JLCPCB seemed to be hung up in customs for an uncharacteristically long time and some packages were opened, and then it just stopped and things returned to normal.
Would that distributor be based in Mn? If so, I had a similar experience some time ago, but I don't remember exactly when. At first the order was "being audited for compliance" or something like that. It stayed that way for a few days so I called to see what was up. At that time there were no questions, just "Oh that order has been processed, it will ship today." Sometime later I got the questions when I ordered more parts. I have been buying stuff from them since their red and white catalog had only 8 pages and was 4 X 5 inches in size.
We took our experiments to an area where there was nothing around except abandoned junk cars that had mostly turned into rust. It was the same place we used to shoot old TV sets with rifles and shotguns to reduce their size. Now over 50 years later it is a housing development south west of Miami.
It might be possible to use match heads, smashed charcoal briquettes, and powdered sugar to do something similar. Fit it loosely into a empty toilet paper roll, then wrap it in newspaper that has been soaked in a mixture of Elmers glue and water until it's about the size of a (US) football. Let it dry in the Florida sun for several days. Light fuse, get away.......far, far away!
We took our experiments to an area where there was nothing around except abandoned junk cars that had mostly turned into rust. It was the same place we used to shoot old TV sets with rifles and shotguns to reduce their size. Now over 50 years later it is a housing development south west of Miami.
DK had informed me by e-mail on two consecutive days that my order had been “delayed” and that they apologize - with that last batch of MJL21194’s. I did put it in within 24 hours of them showing up in stock, I’m not sure if that has any bearing on it. And it did take an extra day beyond what it was supposed to in transit, too. Wasnt any evidence of tampering, though.
Well, I am going to blow the roof off the place with it all… when it all finally comes together. You should be able to hear it from space.
Well, I am going to blow the roof off the place with it all… when it all finally comes together. You should be able to hear it from space.
Attachments
Oh geez...You guys reignited an embarrassing memory from my 15th year of idiocity...
It was 1969, I was living in an apartment with my mom at the time, and one of the kids I hung around with (impish trouble maker) came by with a 4 inch section of half inch galvanized pipe with caps on both ends and a fuse sticking out the side through a drilled hole...yep, it was a pipe bomb! I had never seen or even heard of such a thing and I didn't think it would work...but I was wrong...he put it in an open garage (that shared a common space within the same structure with all the other garages, separated only by chicken wire) and lit it. We were only about ten feet away and...KA-BOOM! I felt the blast, my friend got hit by something from the explosion and was bleeding a little on his arm...we ran as fast as we could back to his house, but never got caught. I found out later that a half dozen cars had been damaged. We were lucky it didn't turn out worse. Lesson learned.
Mike
It was 1969, I was living in an apartment with my mom at the time, and one of the kids I hung around with (impish trouble maker) came by with a 4 inch section of half inch galvanized pipe with caps on both ends and a fuse sticking out the side through a drilled hole...yep, it was a pipe bomb! I had never seen or even heard of such a thing and I didn't think it would work...but I was wrong...he put it in an open garage (that shared a common space within the same structure with all the other garages, separated only by chicken wire) and lit it. We were only about ten feet away and...KA-BOOM! I felt the blast, my friend got hit by something from the explosion and was bleeding a little on his arm...we ran as fast as we could back to his house, but never got caught. I found out later that a half dozen cars had been damaged. We were lucky it didn't turn out worse. Lesson learned.
Mike
Back in the day before Internet, I used to get the run around from suppliers about not being eligible because of tax status. Of course you can order from Digikey but they don’t have parts for Real Amplifiers and Mouser didn’t back than either. Not only do they expect you to pay the 5% tax, but the incredibly stupid amount of RETAIL so that somebody else can order it for you. Fine when you need one stinking $11 transistor they charge you $33 for, but trying to rebuild a burnt out CS800 cost more than buying one NEW. Then along came MCM and $3.90 2SD424’s. Now we’re getting somewhere.
My good buddy back in middle school was making warheads for model rockets using gunpowder and glue. They go up, and the ejection charge detonates it. Was working with gunpowder on the bench - right next to a plugged in battery charger. He came to school one day with a VERY red face, which stayed that way for weeks. Surprised he could still see. That was the end of those particular experiments. His parents put their foot down.
After losing several rockets when the parachute opened and caught a wind stream aloft that was not felt on the ground, I modified my rockets. I built the simplest possible rocket, a tube about 8 inches long painted hi visibility orange or pink with the nosecone glued in, three fins and no clip to hold the engine in. On a windy day use an engine with a second or two delay before the ejection charge ignites. Rocket goes up, engine burns out and rocket flips over and starts toward the ground. The ejection charge goes off popping the engine out and blasting the rocket toward the ground. Look around for the fins sticking out of the weeds, pull it out wipe the dirt off the nose cone and relaunch. On a non windy day use an engine with no delay. Here the ejection charge kicks the engine out and sends your rocket further up in the sky, before it flips over and falls to the ground. They usually don't get stuck in the ground and can be harder to find.
I had an old rocket that had flown many times and was getting ugly so I stuffed the tube full of firecrackers before installing the engine thinking that the rocket would be destroyed. Surprise, the ejection charge lights most of the firecrackers AND blows them out of the rocket before sending it back to the ground in one piece. This became my usual rocket launch technique. I think I lost a few rockets due to a stuck firecracker, but not many.
I made some big firecrackers nearly every 4th of July and New Years Eve as my neighbors grew to expect it. One year a friendly cop saw me in the yard in late December after 9-11. He told me not to make any more since they were all told to arrest people on felony charges of "using a destructive device." No more big firecrackers.
Note that a one gallon Gatorade or Ocean Spray Cranberry juice bottle makes a very big bang when subjected to a 125 PSI air compressor for several seconds. A 1 or 2 liter soda bottle will withstand that pressure.
I had an old rocket that had flown many times and was getting ugly so I stuffed the tube full of firecrackers before installing the engine thinking that the rocket would be destroyed. Surprise, the ejection charge lights most of the firecrackers AND blows them out of the rocket before sending it back to the ground in one piece. This became my usual rocket launch technique. I think I lost a few rockets due to a stuck firecracker, but not many.
I made some big firecrackers nearly every 4th of July and New Years Eve as my neighbors grew to expect it. One year a friendly cop saw me in the yard in late December after 9-11. He told me not to make any more since they were all told to arrest people on felony charges of "using a destructive device." No more big firecrackers.
Note that a one gallon Gatorade or Ocean Spray Cranberry juice bottle makes a very big bang when subjected to a 125 PSI air compressor for several seconds. A 1 or 2 liter soda bottle will withstand that pressure.
The electrolysis rig mentioned in #5 was ultimately used to fill 2 liter bottles full of hydrogen. It was also great fun just to watch the gas boiling off of it, at the school’s expense.
Problem is the electrodes corrode and the reaction starts going south producing undesired cations. Increasing the resistance and slowing down the current flow. Solution? Clean it off with your bare hands while it’s running. Made the mistake of yanking out the center electrode with my other hand still in the water. Inductively filtered power supply. You know how that ends - with my *** on the floor seeing stars and lucky not to be in the morgue.
Problem is the electrodes corrode and the reaction starts going south producing undesired cations. Increasing the resistance and slowing down the current flow. Solution? Clean it off with your bare hands while it’s running. Made the mistake of yanking out the center electrode with my other hand still in the water. Inductively filtered power supply. You know how that ends - with my *** on the floor seeing stars and lucky not to be in the morgue.
My first manager at National Semiconductor was arrested on July 4th one year for setting off acetylene bombs. He was also ordered by some corporate safety dude to remove the Jacob's Ladder he had in his office. Meh... 15 kV @ 15 kW has never hurt anybody... Just don't stick your fingers there.
Our applications guy also concluded that it was a really bad idea to discuss BOM changes while at the airport.
Tom
Our applications guy also concluded that it was a really bad idea to discuss BOM changes while at the airport.
Tom
Spent 2 hours this weekend trying to buy a DPDT switch in my area.
No dice, I could have bought an arsenal of automatic weapons in half the time. Clearly, our forefathers forgot to add something to the Constitution to protect DIY parts.