I couldn't resist.
I don't recommend anyone try building their own DIY setup. Leave it to the pro's, but since what I wan't doesn't exist I have to make it.
I made another DIY tiny stim box. Off the shelf cheap tens unit, isocouplers soldered onto each button, raspberry pi zero w, 3axis 2-8g direction/shock sensing breakout, boost/charger breakout, 500 mah battery, a mini latch button switch. Total cost around $80 for all boards and wires, buttons, stim unit, ect. I wrapped the hole thing in ducttape and then covered the whole thing with a thin layer of 160F thermal plastic to give it a hard case.
The tens unit it self was a cheap Chinese one that was pretty small, but I want to be able to control the up/down and change the mode and time. It uses the inductor capacitor h-bridge construction. I don't know the output, it has the same settings as the last unit I used. I use mode "8" "cupping" which is like intense mode thats on for 30 seconds and off for about 10, repeat. This unit feels only slightly less intense as the last one but it was $30 less.
This is all in self contained unit that runs everything off of 1 battery. I've got a high quality battery charger built into it. Version 1 of my mini-stim system had 3 small boxes daisy chained via wire (battery, raspberry pi zero w, stimunit). This one was broken down more so and sandwiched together.
-Retired/Killed it while modifying it
-HFO Certified? Yes.
-Beeps on level change? Yes
-Size, small but daisy chained to three boxes, battery very large
New V.2 Mini-Stim
-Size is 1 inch thick by 3.5 inches long by 2 inches wide. 1 self contained unit
-Beeps on level changes? No, completely silent
-HFO Certified? More Testing Needed.
It's a lot bigger than I really wanted and I know I can make this smaller with changes. It still fits into the waistbands of your clothes should you want take it with you.
A raspberry pi is completely overkill on this project.
Easiest solution would be an ATTINY85 or so chip as the brains. Nice thing about the pi is it can be updated and controled over wifi.
I'm using off the shelf tens units as I don't know how to make my own inductor/capictor/h-bridge circuit. In most of these tens units the Ten's part is the size of an American Quarter. Pretty sure this thing could be .5 inch thick 2 inches long by inch wide if you could make your "tens" breakout with smd transistors.
Right now the programming is if 2g's (gravity force) are felt, it ramps up to 100% and stays there for a few minutes and then ramps back down to 0 and waits until another 2g's are detected.
Another program I made ramps up based on time stamps for a video of an adult movie I have.
Sensor in it can also detect xzy movement and direction. Lots of things can be done with this.
Still not as powerful as the full fledged flagship estim units. Still less powerful than transformer based E-stim boxes.
Learned some things. I will use Silicone coated 22awg wire next time, issues with wire being to stiff, silicone wire could fix that. Instead of using an 4-dip isocoupler for each button, I'm going to buy a 4 channel array isocoupler and run wires to the buttons. I like the boost/charger breakout and 500mah is a good sized battery. Debating infinite programming posbilities but larger size with a Pi vs a single use/function but super tiny, ATMega tiny chip.
Wish there was a schematic of a inductor/capcitor/h-bridge estim unit build somewhere. Tried looking but the only ones I can find online use a transformer.
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