I think I've told this story privately a hundred times. Okay, maybe not quite a hundred, but a lot of times. So rather than do 101, I thought I'd write it here for everyone to enjoy, and laugh a little as a proof-of-concept which mostly worked. Mostly.
I'm not 100% sure the year this was, but it was around 2000 or 2001.
I had this idea for an electronic leash which could be used in public. But totally invisible. I wanted the wearer to be able to hide it under clothing.
I thought about this for a while, and realised that I could use a low power transmitter to roughly measure distance, and because this was a proof of concept, I bought a cheap radio controlled toy which transmitted at 433MHz. It had two channels, but I only used one. I gave the transmitter a better battery, and set it to transmit constantly. On the receiver I wired the output to hold the power OFF the punishment circuit if it was in range. I did some tests and the NiMh battery I had pulled out of an old Nokia phone actually ran it for several hours. These days I'd use an Arduino and some custom RF modules, but they just weren't available then.
Functionally, it was simple: if the receiver was in range, the punishment circuit was off.
If out of range - which meant about 5m for this toy - it powered the punishment circuit.
That "punishment circuit" was a TENS unit: a shock generator. That's why I have the design of one in my gallery feed on Imagefap (link below). At the time I didn't have that design, but I was able to buy a bunch of those ridiculous "tummy firmer" shock generators which supposedly made you lose weight by shaking your stomach. Total and complete BS of course, but it was designed safely and had been through certification, so it was perfect. I recall they were originally sold for about $100, but I bought a handful for $5.
The actual design was meant to have the electrodes be large metal plugs inside a chastity belt, but that wasn't appropriate for my friend who was volunteering to test this. She is just a friend, albeit one who is rather curious about my kinky side. It appealed to her to take part, even though she was somewhat nervous. So she placed a medical electrode pad on her ass cheek, and another on her stomach. Both were covered by a chastity belt I manufactured, as the electronics mounted on that belt.
Then we went to lunch. We confirmed it worked: if she wandered more than 5m away, she returned REALLY fast. It was set to quite low, but she said it wasn't fun. So a successful test seemed to have happened.
After lunch we decided to do some shopping at a local mall (Macquarie Centre for those in the Sydney region), and there was a toy store we wandered past. Suddenly she tensed, grabbed me and said "run! Fucking run! NOW!!!!! Fuck fuck fuck!!!!"
She dragged me about 10m along the corridor, swearing, until she relaxed.
What had happened was that something else, and something more powerful, in the shop was transmitting at 433MHz, but I guess using a different encoding. As such, my little transmitter was drowned out by a stronger signal the receiver just couldn't understand. At the same time, the piece of crap tens unit had somehow set itself from setting 2 (out of 10) to 10. No idea how that happened, but as I said, it was a piece of crap.
Anyway, my friend got the full power of an electronic shock generator on high between her stomach and ass until she dragged me away from the interference.
Needless to say, she was NOT impressed. She still reminds me of it, to this day, if I ever suggest making anything. And she has never again volunteered to be a guinea pig for me. I can't imagine why.
Link to the TENS unit design referenced above: www.imagefap.com/pictures/5155…