In 2024 there are various options available for commercial, pulse-based boxes. Suppose we want to output our custom pulsetrains, how well do these devices stack up?

eStimSystems 2B

The 2B is a device that is over 20 years old, it has some quirks:

• The output stage is only capable of generating assymetric cathodic-first pulses. This greatly limits creativity in signals and has some questionable safety implications. We are not aware of any reports of harm, but this does appear to accelerate numbing.
• The device features an audio-in. Various firmware versions interpret the audio input differently. The audio interpretation algorithm does not appear to have any logic behind it. The limitations of the ancient microcontroller means they can't fix this either.
• The audio mode only generates pulses with identical phase on both channels, greatly limiting signal generation freedom.

Below are some scope shots of the output with various audio input signals, kindly provided by hurtmeplease on discord.

Their comments:

2B Scope results: pulses on L and R are always at the same time, and that time is only controlled by the Adjust value.
Phase has no apparent effect.

latest 2B beta looks even less promising. The pulses continue to have no obvious relation to either the frequency or the phase. What's probably worse, they are consistently offset with a gap between the pulses of maybe 100 us.

Their system is really odd. I tried using their serial protocol to control the levels in their continuous mode, and even that takes seconds to reach the desired power.

It is pretty clear that we can't massage the 2B into generating the signals we want, making it useless for our purpose.

Erostek 312 family of devices

The 312 is a family of devices that is also based on ancient design, some features of the hardware:

• It generates balanced biphasic pulses.
• The polarity can be swapped.
• The conversion from audio to pulses appears to be relatively straightforward, it generates a pulse every zero crossing up to 333hz: https://discord.com/channels/720377642813095956/869605382312583168/1079420915282096218
• It appears to be capable of generating threephase signals in audio3 mode, although I have not seen proof of this.

It might be possible to massage the audio input in such a way that we can generate complex pulsetrains, although nobody has put in the work required to do so.

Coyote

The coyote is a relatively modern design, version 2.0 was released around 2022 and version 3.0 in 2024.

• Version 2.0 is unsuitable for fast-changing waveforms because the waveforms can only change 10 times per second. Apparently this has been increased to 40hz in version 3.0.
• Only outputs symmetric biphasic pulses.
• Cannot output overlapping pulses, greatly limiting threephase effects.

It's better than the other devices in some ways, but not in others.

Future hardware

NeoDK is a new open-source design that aims to fix the issues with existing hardware. https://github.com/Onwrikbaar/NeoDK