[political] Chipshouter OSH

Hi Guys,

I really do not want to offend you with this post and I hope you’ll try to understand this out of my point of view.

I searched the forum quickly, but could not find something related.

So, I’m basically wondering, why the ChipShouter (CW520) is not OSH
At the hackerspace there are like two ChipShouter devices. But when I wanted to lookup the actual design and not simply use them as a black box, it seems to be closed HW. I simply wanted to learn more about designing reliable and especially safe EMFI HW and afterwards probably decide to get one solution myself in private.

As I am a really big fan of your company and your projects, I would like to understand your decision in making exactly this one closed source.

I did not open one of the devs yet, because of the probably lethal voltage generated by the CapBank. … I do not want to accidentally kill one of my colleagues, cause I still need them at the moment. Maybe afterwards, when our projects are done :smiley: :japanese_ogre:
Anyway, I think about the design as kind of simple:
CapBank, ChargingCircuit, some FET to trigger the discharge, MCU for settings and probably some Error-State detection && Coping with these errors.

Opposite to my imagination of the HW design
–which may be incorrect, as I did not checked yet–
there is the price, which is way higher than for the OSH boards. Of course with this one, there have probably been lots of lots of research needed which is non-negligible. There is just nothing comparable… but still expensive though… especially for enthusiasts or students.

As I mentioned, I’m a big fan that just don’t want to loose his faith.
Sounds kind of weird, but this is what it is.

I would be happy, to hear from you. :slight_smile:
Further, I’m writing this in public because I know at least a fistful of guys who also wonder.

Take care && all the best,

Hi Marvin,

@coflynn can probably answer your OSH question.

I think the cost difference can mostly be chalked up to safety features present on the ChipShouter that aren’t present on the lower cost boards. For example, the ChipShouter has the FET on the high side of the coil to prevent the coil from being directly connected to the high voltage of the capacitor bank. This makes the driving circuitry more complicated, thus driving the cost up. Again @coflynn can probably answer this better than I can.


Hi Marvin,

Additionally you might enjoy this highly entertaining talk which talks about some of the dangers of designing and building EMP devices.


Hi Marvin,

It’s indeed not OSHW - we played a bit with it, and various reasons in the end! Partially for commercial reasons, as the higher-margin stuff like CW-Pro & ChipSHOUTER help us keep other material like tutorials open-source… selling only the lower-cost stuff (CW-Nano/CW-Lite) would mean we couldn’t have great people helping out here as couldn’t afford to hire anyone :wink:

But also the design of pulse generators is also pretty well researched - so there is some interesting stuff still inside it, but the “novel academic value” isn’t really there. The BadFET design was already there when we released ChipSHOUTER, and several others have come out since then (that is - open-source EMFI).

The main issue remains in liability though. If it was only a kit or OSHW it would be clear when someone built their own. But when we offer both, there would be a risk someone modifies the device (or builds their own) and blames us. The internals use special high-temp FR4, then have two layers of high-voltage protection for example (conformal coating over entire PCB, then a separate layer of high-temp epoxy/potting over the high-voltage stuff), in addition to polymide high-voltage insulation over parts of the internal aluminum case, and finally a grounding connection to the enclosure. That is in addition to the hardware interlock, plus a bunch of firmware “fault detection”.

All of those safety things are a hassle during the production (coating, curing, recoating, etc), and the firmware fault detection is annoying when you are using it. So I’d be pretty sure someone doing a DIY build would skip those features :wink: Even if it’s somewhat frivolous, the cost of defending from any sort of lawsuit would do a lot of damage to us!

OSHW for more serious gear is a bit of an open problem. Lots of people just want cheap ahead of anything else… I supported ScopeFun for example, but on the forum there was at least one person complaining on the price. Apparently they are happy to give Digikey/Mouser etc a reasonable profit margin, but as soon as the designer tries they complained. It’s far from the only time I’ve seen that! You also notice some of the historical supporters of OSHW had a strong commercial incentive as they built a business out of selling low-cost gear but selling lots of it (SparkFun etc), so OSHW is far from a simple answer to me!

So we kinda did this one where we’ve publish a fair amount of details (the block diagram in the user manual is relatively accurate to each block), at least moreso than other commercial solutions we found. That block diagram shows you how to avoid some of the ‘oopsies’ we did in blowing up stuff during development.

Originally we had planned on some lower-cost “ChipLoudTalker” that was open-source but more limited. Other architectures allow you to avoid exposing the high-voltage without the complicated high-side driving, at the downside of requiring more specific ‘injection tips’. But we’re already way behind on stuff as-is so that never made it beyond the “cool idea” phase :wink:

Warm Regards,


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PS - to your first note too - not at all offensive, a good question! The whole “how to OSHW” is interesting and IMHO there is a lot of good discussions I normally have at conferences etc around that.

There is lots at each “end of the spectrum” - cool OSHW that you can’t buy because it’s not sustainable for someone to support as a business, and super-expensive commercial gear that you need to re-mortgage your house to buy. I’d love to see more in the middle…