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Circuit building: stop using antique parts (2014)

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141–150 of 169 posts

Re: Circuit building: stop using antique parts (2014)

#141
post #134

I've recently gotten back into hobby electronics, trying to revive all that EE knowledge I haven't used in 15 years, and one thing I sorely lack is knowledge of common components to use. Online electronics stores are no help because of the overload of possible components. Is there some sort of Cookbook out there I could refer to for up-to-date examples of common circuits and electronic tasks? I mean, I otherwise tota…

Octopart (YC'something, now part of Altium) have an excellent Common Parts Library: https://octopart.com/common-parts-library I also often refer to Sparkfun's product list as a reasonable starting point.

Octopart is much nicer than http://findchips.com (which has been around about 20 years, searches many more vendors but doesn't consolidate pricing)

Re: Circuit building: stop using antique parts (2014)

#142

IGBTs, although very expensive, are also interesting alternatives to MOSFETs and relays where large voltages need to be switched where speed isn't critical.

Here's an example of a very large module for 4.5kV and 1.2kA

https://www.infineon.com/cms/en/product/power/igbt/igbt-modu...

Re: Circuit building: stop using antique parts (2014)

#144
post #23

If you want to switch power, MOSFETs are the way to go today. Voltage drop is near zero. Digi-Key has over a thousand MOSFETs in TO-220 packages. Here's one of the cheapest with a low gate threshold.[1] Probably good enough for most Arduino on/off applications. MOSFETs do have some problems. They can draw large gate currents for the first few nanoseconds of turn-on, which can overload whatever is driving them. The ga…

> If you want to switch power, MOSFETs are the way to go today.

But, even the mosfet is old. IGBT (depending on loads, but especially for slower switching)

Re: Circuit building: stop using antique parts (2014)

#145
post #17

Mechanical relays are not obsolete. They can have lower resistance and capacitance than solid state equivalents. A good relay is a very close approximation to a plain wire when closed. Relays are still commonly used for RF switching.

I use mechanical relays to switch AC power for pumps and similar AC motor loads using DC signals from Arduinos and similar. I have very very little experience with electrical engineering (I'm in the Lego mindset of I plug things in according to things I find online until they work), but is there something I should be using instead with 120V ~3-5 A loads?

IGBTs. Solid state, 0 crossover, lower voltage to drive. Similar failure mode, but many more switches.

Re: Circuit building: stop using antique parts (2014)

#147
post #119
post #103

Earlier quoted context omitted.

ADC, MCU, DAC, done. Cheaper, too -- I think 50 cent ARMs can do that these days. Any pedal that isn't digital today is just nostalgia (like tube headphone amps and the like.) Digital is the clear better choice even for sound shaping.

> ADC, MCU, DAC, done. Cheaper, too -- I think 50 cent ARMs can do that these days. And yet smart engineers keep using Analog Devices SHARC DSP's for effects on audio interfaces. So SOMETHING must not be quite as simple as your claim. (The answer is that most of these guitar effects are VERY non-linear and simulating non-linear stuff digitally is very much NOT straightforward in real-time.)

not smart, but old school and embedded in big companies Devkit alone is >$1K and you wont be able to do anything with it without couple of $K in software and maybe even support contract. All that for ~$10 Arm Soc performance.

Re: Circuit building: stop using antique parts (2014)

#148

Earlier quoted context omitted.

I disagree. Using a stencil and paste with a cheap toaster oven is easier to make high quality boards than with PTH and an iron. It's fast and almost always comes out great.

"easier". Just pull apart a toaster oven. Reconfigure it. Rewire it. Get some paste. Make a stencil. You know. Easy peasy. Get the software. Learn how to use it. Get the stencils printing. Easy. Oh, you've got registration problems. Come on! Its easy! So much easier than spending one minute ordering a through hole component. You see, its not actually "easier". Its "easier" to you because you already have the equipmen…

Hey, I teach SMD soldering to absolute beginners, many of whom have never done ANY electronics. Within an hour and a half they have a working board with "advanced" components like QFNs and 0402 passives attached. Nobody goes without a working board. Only equipment needed is a pair of tweezers, a metal squeegee for paste deposition and a plain off-the-shelf $10 hotplate. No fancy anything. It's not a setup you'd use for high-volume production, but who gives a shit, it's enabling technology for hobbyists to use modern parts. I call it "surface mount electronics assembly for terrified beginners". If you can make it to an event I'm teaching at, I'll give you a free class, as you're EXACTLY the kind of person who would benefit most from seeing that there's a middle way between relying on increasingly unobtainium components and having to have a pile of fancy expensive stuff to be able to work at all.

Re: Circuit building: stop using antique parts (2014)

#149
post #61
post #38

Earlier quoted context omitted.

True but i think a lot of that is in adherence to the original design/specs they're emulating (or straight up ripping off). Folks went nuts over the XVive BBD revivals or even still pay ridiculous sums for original panasonics. Sometimes there simply aren't alternatives to achieve the same circuit or you're repairing something very specific (although that's probably outside the scope of the article's PoV). As well the…

> I doubt side by side they sound noticeably better but if you're building vintage it only makes sense to keep the 'tronics true to the time period. In vintage radio repair, they sometimes will replace old caps (usually electrolytics) with new ones, but put the new ones inside the old cans - to preserve the look of the device. Obviously, though, this won't work with all parts...

Old car dash instruments are often upgraded the same way. They use new parts to drive the original indicators so it all looks correct, but is actually accurate.

There are even kits to replace the guts of old car radios with modern stereos while preserving the controls and dials and their function.

Re: Circuit building: stop using antique parts (2014)

#150
post #28

Earlier quoted context omitted.

Yep. It is indeed easy to ruin a FET with minuscule amount of static charge. That is, unless there is a zener (or two, back-to-back) connecting gate to source. Many modern FETs have this built right in. E.g. ATP214 [1]. [1] http://www.onsemi.com/pub/Collateral/ENA1712-D.PDF

That does sound like a very useful part for learning purposes, as well as general robustness, but they don't appear to be particularly common. I get no results on eBay, nor can I find through-hole packages. Do you know of anything available like that?

NXP makes a version of the popular 2N7002 with ESD protection: http://www.nxp.com/documents/data_sheet/2N7002CK.pdf

Surface mount only (like most modern transistors), but SOT-23 isn't too hard to hand solder. There are lots of breakout boards for surface mount packages available for prototyping, or you could even solder some mod wire directly to each pin and put some hot melt glue on it to keep it in place.

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