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Jason

I'm just throwing this one out there -

We have need of some power electronics, which include inverters and motor controllers. The primary cost of these circuits are the power electronic components. While we could definitely look at what it would take to make some of these semiconductor components, another option would be to look into what it would take to make vacuum tubes. This could potentially cut out those $20 mosfets we will need, and all the other components should be inexpensive in comparison. We aren't creating perfect audio here, or trying to make a communications system. We're simply powering stuff. Maybe its feasible.

AndrewBuck

I know a lot of large radio transmitter (for radio stations and the like) still use vacuum tubes because they can more easily be made to handle very high power applications. I am not an electrical engineer so I don't know the details of how they work, but the project does have proposals for many such high-power devices (iron melting furnace, welder, plasma cutter, etc). I think rectifiers can also be made from vacuum tubes so you could recify "wild" AC from wind generators, etc, down to DC for storage in batteries.

Here is a good video I saw a while back on the entire process of making tubes. It is definitely within the realm of possibility for the shop we have to do (would require a vaccum pump and a few other specialized tools but most of the other tools are pretty standard equipment.

Dawg

@ Jason - I'm fairly familiar with tubes because we use them in Amateur Radio. The problem with tubes is they are relatively high voltage devices and not very efficient. Even small ones run pretty darn hot. All that filament heat adds up in the end. I highly doubt they would be useful in very many applications. It might be doable some day with a ton of R&D.

The Dawg

dorkmo

i think its worth looking into further. its a pretty vital function in electronics and its something that can be hand done on a small scale, which i think is sort of our niche. i think we should try to at least have a working knowledge of the manufacturing process on the wiki. so we can use it if needed and improve if possible. i worked on the ceb controller box a month or two ago and had to order some mosfets. they were relatively expensive considering the rest of the costs. i'd always rather build something that buy it.

Hilscher

Plastic semiconductors and microchips exist. Create plastic from water and carbon and energy, then 'print' the microchip for motor controls. It only has to be sophisticated enough to follow instructions from a 'real' computer. It doesn't have to act as display and storage too like the big proprietary firms working with plastic technologies do. Is this at all possible to achieve in the short(ish) term? As much as possible should be cut out, and electronics is one of the biggest things the GVCS is beholden to. Electronics just cannot be substituted or bypassed for creating the modern elementary comforts of life on a DIY basis.

Jason

After further research and review, it appears that we won't be needing $20 transistors for stepper motors. I first found a $20 H-bridge but later found drive circuitry for around $5. I don't claim to know what the differences are between the two at this point, but it doesn't seem to be as bad as I thought.
http://openfarmtech.org/wiki/Stepper_Motor_Controller#Motor_driver_chips_and_H-bridges

Larger DC motors as well as large power inverters are still an open question though. Also, a prototype stepper driver needs to be built before full requirements are for driving stepper motors.

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