I was a teenager at the time I did this one. I was a quiet person, and reserved - and introverted, so it was unlike me to do this.
I was getting in to electronics, reading everything that I could get my hands on - especially if it was free. This was in the mid-70's when there was no internet, so things worked differently back then.
I had a facination with LEDs (which were relatively new commercially), and was also fascinated with flashing the LEDs using minimal current. I had lots of time, and spent a few weeks developing a small flashing tie-clip. I started by using an older tie-clip, and drilling a small hole in it. I then placed an LED through the hole, and bent the leads over on the backside.
The leads then went to a pair of wires that I had from a donor earphone. The older kind that had a 2.5mm plug on the end. I scavenged a mating receptacle from an old transistor radio. The LM555 IC I used was wired up in a mode to charge a capacitor and then flash the LED about once per second. The electronics were housed in a small 1-inch square by 1/4-inch thick little plastic box that a phonograph needle had come in.
The 9-volt battery was in a separate box that a radio tube came in. It had its' own wiring that went to the small 1-inch plastic box.
Anyway, all of this sounds like a lot, but I was proud of my 'micro' circuitry skills. To implement this LED Tie-clip flasher, I had to first clip the tie-clip onto my tie, then run the wiring down the inside of my shirt to the plastic housing. From there, I had a pair of wires that went to the battery box that had an ON/OFF switch on it. The battery box was in my pants pocket where I could turn the flasher on and off unnoticed.
since I was so introverted, I almost didn't go through with wearing this, but figured that if I didn't want to turn it on, at least I had worn it to a meeting.
It was a Thursday night meeting that I chose to wear the tie-clip flasher to. I didn't turn it on during the meeting, or if I did, the only person to see it would have been the person on the stage. Since I was in the back, I don't think they would have seen it from up there, that far away.
After the meeting, I would turn it on, and it would start winking and blinking. I would not say anything, but people would do a lot of double takes. When they would look, I would discretely turn it off, and it would just look like a small translucent stone attached to my tie-clip.
I had a few people ask me about it, and I would confess and tell them, "Yes, it's a flashing LED." Now days those things are common, but back in 1975 or so, they hadn't even invented the LED watch, yet. But, they would nod, and say something like, "I thought so." not really sure what an LED was.
There was one fella - Bob Cr*** - who was a company man. Very strict. He was talking to another fella, and I was able to get in front of Bob, and turn on the LED flasher. *wink* *wink* *wink* away it went. Well, Bob saw it, but for some reason he refused to process it and acknowledge it. I tried several times. He never would admit that he saw anything.
I thought that was funny as heck.
I know that sounds mild or tame, but back then... for me... I was really rebellious doing something like that. Yessiree!
I still have that tie-clip... somewhere in storage.
Regards,
Jim TX