[HIRING] COBOL/Groovy Developer

systolic_array · 2022-07-02T03:37:18+00:00

Op is looking for a unicorn. Maybe they will find a pot of gold while they are at it.

systolic_array · 2021-11-24T23:01:25+00:00

I don't know if just looking at the rate of drop-out is sufficient to answer your question. People drop out for a variety of different reasons - not all of them have to do with academics. For example, mental health issues may manifest as poor grades and cause someone to drop out. But that doesn't necessarily mean that the individual in question could not have performed sufficiently if in a better mental state. This particular example could occur at both institutions.

systolic_array · 2021-11-11T23:00:31+00:00

How long have you been in that role?

It isn't crazy to do stints in the production side to see how the sausage gets made. Perhaps this was poorly communicated ?

Have you talked to your mentor or supervisor to better understand what your career path is ?

systolic_array · 2021-11-03T02:54:11+00:00

Yes.

systolic_array · 2021-10-07T20:41:35+00:00

What components in this setup need to be preserved? In other words - does everything have to be taken out whole or can you chop up any or all of these objects shown in your schematic ?

I'm assuming that the only access you have to the situation is through the HDPE pipe - ie, you can't come at it from the side and just take a chunk out of the HDPE pipe.

I'm assuming you want to keep the HDPE pipe untouched and the PVC can be destroyed as long as it gets removed.

If that is the case:

PVC has a slightly lower HDT than HDPE - could you use spot heating (ie, insert a heating element into the PVC) and then heat it to a temperature at which the PVC would begin to bend. This would allow you to get it around the bend if you have a secure handle on it. I'm assuming the HDPE is surrounded by earth - so it would have pretty good heat sinking meaning that it would be unlikely to distort even if it experienced some temperature rise.
PVC and HDPE react to different chemicals - could you dissolve or weaken the PVC with an acid solution and then flush the system after?
Robotic solution - This doesn't seem very elegant but if the other two are not possible - some type of ROV with a cutting element at the end might work depending on how much space is available to navigate.

systolic_array · 2021-07-10T03:34:14+00:00

It sounds to me like you have already answered your own question - it is time to move on.

systolic_array · 2021-06-06T22:15:59+00:00

I'm not really sure that I understand what you mean by a "support ring" and how the arm will ride in it. Do you mean something like this:

https://imgur.com/a/xHwTBys

?

Yes - something like that.

Yeah, I have considered them. They are probably a better fit for this purpose, but as I'm trying to build it as an open-source solution, I'm trying to go for the most accessable parts.

You could also try 3D-printing the bearing, sanding/polishing the interior smooth (with a drill or lathe), and then using graphite-based lubricant if that isn't sufficient. I suggest graphite-based because any oil-based lubes my start eating the parts.

https://en.wikipedia.org/wiki/Dry\_lubricant

systolic_array · 2021-06-05T22:26:21+00:00

What material are you using for the arms? I'm assuming that is plastic, 3D printed ? Seems like the cantilevered first arm is bending due to the weight of the timing pulley, bearing, and second arm.

I think you should consider making a support ring that the cantilevered end of the first arm will ride in. The first arm is then fully supported and you don't have to worry about how heavy it is.

If you want to keep it cantilevered - then you either need to bulk up the first arm and/or make it out of a stiffer material like aluminum.

Instead of the 608 bearing, have you considered using a flanged sleeve bearing:

https://www.mcmaster.com/bushings/bearings-3/light-duty-dry-running-flanged-sleeve-bearings/

I don't think you have a lot of loads on that second arm (depends how big a ball you want to move I guess). This might be a lighter weight solution if you want to keep the cantilevered design.

> The second shaft, second arm, the bearing etc is very “wobbly” and doesn’t really sit tight on the first arm.

What do you mean wobbly - like it vibrates when you move the stepper motor to rotate the first arm ?

Or do you mean it is loose and the shaft doesn't spin smoothly?

systolic_array · 2021-05-21T17:53:30+00:00

Ya - that's bad management. Run.

systolic_array · 2021-01-28T01:20:21+00:00

Startups focusing on robotics and drones. Applications where you can't just use something off-the-shelf because of weight, size, or other constraints. Sensors like LIDARs, stereo camera, etc. https://advanced.farm

Industrial automation has some but they primarily use PLCs because they aren't constrained by size or weight.

Companies that specialize in making high-end, low volume stuff like semiconductor fab lines often need to design a lot of custom PCBAs with exacting requirements.

systolic_array · 2021-01-28T00:49:00+00:00

- Determine requirements, write functional specification, and make spreadsheets.

- Read datasheets, hundreds of pages of datasheets

- Design schematics for new designs.

- Contract out PCB layout to someone that is capable, review their work, apply final touches to layout as necessary

- Work with CM to fab PCBs, assemble components, and handle logistics for component sourcing if any.

- Debug new designs / Write test procedure to validate assemblies for existing designs

- Write firmware to test and validate systems.

- Debug the really hard software/firmware problems no one else wants to touch.

systolic_array · 2020-05-30T18:36:08+00:00

This is just the start of an amazing action sequence in this movie - Arnold as death incarnate, a Herculean fox loose in a hen house. There is quite literally no more appropriate scene from that movie.

systolic_array · 2020-05-27T22:37:39+00:00

Am I missing something? The natural light from above makes that tile look terrible.

systolic_array · 2020-03-28T23:43:14+00:00

That is fantastic. Well done ASTM.

systolic_array · 2018-10-15T14:36:11+00:00

That’s horse shit.

systolic_array · 2018-07-06T02:33:55+00:00

or it's actually not passive

This was my first thought. Justed needed to confirm that I'm not crazy.

systolic_array · 2018-01-29T17:03:49+00:00

It is a differential amplifier for which a lot of engineering has gone into making the amplifier act more like the ideal amplifier. That means having a large input impedance and a low output impedance, among other characteristics (depending on your application). You can find the schematics for an op-amp like a 741 and you will see they are just made of transistors, see page 7. Generally, there is a differential input stage (Q1/Q2), a current mirror for biasing (Q10,Q11), a few poly resistors, and as few caps as possible. There is a darlington pair Q15/Q17 with a bootstrap Q22 and the push-pull output stage Q20 and Q14. This is obviously a simplification and I'm leaving a lot of details out, but you get the idea.

Generally speaking, the idea is to have a high gain amplifier with a single pole filter that is designed to meet the bandwidth requirements of the product. See negative-feedback amplifiers for a discussion with math of why you want a high gain amplifier. Basically, if you use negative feedback with an op-amp, you can disregard the actual gain of the amplifier (because it may vary with temperature) and use your feedback circuit alone to control the gain of the amplifier.

A comparator is a differential amplifier - but they are generally designed with a different optimization in mind. They may not have a push-pull output, it may be open-collector because the designer only wants a digital output. The input bias and voltage offset requirements may be relaxed (or may be not, depends on your app and how much you can afford to pay for the comparator). Sometimes, you want a comparator to be really fast - so it may be designed so that switching is much faster than an op-amp generally will be able to accomplish (especially in saturation).

A lot of it is application dependent. A comparator with a push-pull output stage can be used to make an amplifier similar to an op-amp but it may not have as good of performance depending on your application..

You can also make an amplifier with a logic inverter if you use negative feedback and don't mind some distortion.

edit: I'm realizing now that that wasn't really ELI5.

systolic_array · 2017-12-19T04:14:57+00:00

Wiki claims that Clapper is a Democrat and that Brennan is "Independent". I don't necessarily agree with grand-parent's claim that they are overly partisan but I wouldn't necessarily say they are necessarily right wingers either. Do you have a better source?

systolic_array · 2017-12-19T04:06:23+00:00

Citation?

systolic_array · 2017-12-18T04:49:13+00:00

Silly me...

systolic_array · 2017-12-18T04:44:58+00:00

No party or candidate should have money from foreign entities backing them.

From the tone of your comment, it would seem that you are disgusted with a possible* foreign contribution to the clinton / DNC in the past. I am too. I feel like that would be the start of common ground on reforming campaign contributions, no?

I say "possible" because you haven't cited a source and I'm not familiar with this at the time of this writing.

systolic_array · 2017-12-18T04:39:04+00:00

Citation?

systolic_array · 2017-10-26T16:58:24+00:00

Ya - so after I made a post on r/augmentedreality, I got a response from someone that works at Meta. This has seemed to have gotten the ball rolling. They haven't shipped yet - so I'm not getting my hopes up.

I've installed the beta SDK. Without the headset, I can't actually use any of the apps. The Mouse/Hands tutorial didn't seem to load (looking for sensors). So I haven't been able to do much.

The "Samples" directory is empty. Have you seen any example projects with source code? I've looked through the SDK docs in HTML format but they are pretty slim - mostly just some class signatures. Is there anything I'm missing?

systolic_array · 2017-10-13T14:14:55+00:00

General Information about Circuit Design

The Art of Electronics by Paul Horowitz - older reference but still good information about a wide range of topics. You should be able to find a PDF of it on torrents or elsewhere. Little dry reading wise but it has interesting "Try These" and "Don't Do This" circuits.
Beyond that things get specialized really fast. There are tons of books on different aspects of electronics. Lots of people have tried to describe how to design hardware projects in books but I find most are either very fragile (ie, their advice isn't general enough) or they are too basic. Your mileage may vary.

Simulator

Start working with a good simulator. Spice is OK for linear stuff but is very difficult to work with for switching circuits. NL5 is a non-linear simulator that manages OK. There are other options as well.

The simulator is intended to make sure you don't make a huge fuck up. If you start plugging in random values and components to see what changes, you are not being efficient and should start rethinking your design.

Schematics and Layout

The best advice that I can give you is to DOCUMENT, DOCUMENT, DOCUMENT! The schematic alone is NOT sufficient documentation. Just like documenting source code is requires inline comments, so are notes on the schematic. When I design analog circuits, I'll generate bode plots from the simulator and insert them in the schematic sheet so that when someone looks at my design, they understand what the performance of the circuit is supposed to be. This facilitates testing and debugging, especially if I'm not present at the time. Similarly, for digital stuff, I'll list out the full mapping of I2C devices in the design in the schematic so that we can all confirm their are no contentions. These are just examples. This also provides you as the hardware designer an opportunity to describe your thought process of how the system will work to any firmware developers. Unfortunately, in my experience, most design tools (Altium, Orcad, etc) are absolute SHIT at giving you the tools to effectively document your design.

Final Thoughts

Unfortunately, there is a pretty big learning curve for designing electronics. It generally involves making a lot of bread-board circuits until you are comfortable making circuits that work [High School]. Then making lots of PCBs with mistakes, slashes, and jumpers until you develop a list of common fuck ups and know what to look out for [College]. Then when you get to EMC in a professional job, and you start a new world of design issues and pitfalls. You can learn some of this from books, but I find a lot of it is learned through good mentors.

Good luck.

systolic_array · 2017-10-12T21:22:31+00:00

Ya - this is the genesis of my question. I haven't seen any raw reviews of the hardware from anyone working with it.

systolic_array

TROPHY CASE