Finishing A Mini PS One: SLA vs Extruded

One of the biggest lessons learned by first time 3D printer users is that not everything can be replicated and a printer is a machine and not a miracle worker. It has limitations in terms of what it can print as well as the quality of the output. For teeny tiny objects, the 0.8 mm nozzle will just not do and with resin printers on the rise, the question is, ‘are extruder printers obsolete?’

[Dorison Hugo] has made a mini version of the PS One using a Raspberry Pi which you can play games one. The kicker is that in his video, he does a comparison of an SLA printer and a cheaper extruder one for his enclosure. He goes through a laundry-list of steps to print, file, fill, repair, sand paint, sand, paint etc to try to get a good model replica of the original PS One. He then proceeds to print one with an SLA printer and finishes it to compare with the first model. The decals are printed on an inkjet for those who are wondering, and there is a custom cut heatsink in there as well that was salvaged from an old PC.

Spoiler alert! The SLA wins but in our view, just slightly. The idea is that with enough elbow grease and patience, you can get pretty close to making mini models with a cheaper machine. The SLA print needs work too but it is relatively less and for detailed models, it is a much better choice. We really enjoyed watching the process from start to finish including the Dremel work, since it is something that is forgotten when we see a 3D print. Creating something of beauty takes time and effort which stems from a passion to make.

Take a look at the video below of the time lapse and for  SLA printer fans, have a look at the DIY SLA printer which is a Hackaday Prize Entry this year. Continue reading “Finishing A Mini PS One: SLA vs Extruded”

Humidity Sensor Shootout

If you want to measure humidity (and temperature, and maybe even barometric pressure) in a device that you’re building, have a look at this comprehensive test of seven different options. We’re going to summarize the results here, but you’ll really want to read up on the testing methodology — it’s great science hacking. Did you know about using saturated salt solutions to produce constant humidity levels for calibration? We didn’t.

The eBay hacker favorite, the so-called DHT22 module, doesn’t fare all that well, with one of six that [Robert] tested being basically horrible, and three of them breaking within two years of use. The one that works well, however, is pretty good. Feeling lucky?

The Bosch BME280 looks great. It costs a bit more as a bare part, and a few times more than that when it is mounted on a friendly module, but it seems to be very reliable. And you get a barometer thrown in for the extra work. Indeed, it performed so well that Hackaday contributor [Nava Whiteford] put the part under a scanning electron microscope to figure out what’s going on.

The other sensors were fine, with the HTU21D and SHT71 being standouts for their ultra-fast response. For the full details, go click on that link at the top. Having just installed a sextet of DHT22s in our house last year, we’re left with that sinking feeling that we may have gotten what we paid for, which wasn’t much. At least they’re all still running.

Thanks to [Dodutils] and [mac012345] via comments in another thread.

AVR vs PIC, Round 223: Fight!

Get ready to rumble! [Thierry] made the exact same Hello-World-esque project with two microcontrollers (that are now technically produced by the same firm!) to see how the experience went.

It’s not just an LED-blinker, though. He added in a light-detection function so that it only switches on at night. It uses the Forest Mims trick of reverse-biasing the LED and waiting for it to discharge its internal capacitance. The point is, however, that it gives the chip something to do instead of simply sleeping.

Although he’s an AVR user by habit, [Thierry] finds in favor of the PIC because it’s got a lower power draw both when idling and when awake and doing some computation. This is largely because the PIC has an onboard low-power oscillator that lets it limp along at 32 kHz, but also because the chip has a lower power consumption in general. In the end, it’s probably a 10% advantage to the PIC on power.

If you’re competent with one of the two chips, but not the other, his two versions of the same code would be a great way to start familiarizing yourself with the other. We really like his isDarkerThan() function which makes extensive use of sleep modes on both chips during the LED’s discharge period. And honestly, at this level the code for the two is more similar than different.

(Oh, and did you notice [Thierry]’s use of a paper clip as a coin-cell holder? It’s a hack!)

Surprisingly, we’ve managed to avoid taking a stray bullet from the crossfire that occasionally breaks out between the PIC and AVR fans. We have covered a “shootout” before, and PIC won that round too, although it was similarly close. Will the Microchip purchase of Atmel calm the flames? Let’s find out in the comment section. We have our popcorn ready!

A Comparison of Hacker Friendly SDRs

In the market for a software defined radio? [Taylor Killian] wrote a comprehensive comparison of several models that are within the price range of amateurs and hobbyists.

You can get started with SDR using a $20 TV tuner card, but there’s a lot of limitations. These cards only work as receivers, are limited to a small chunk of the radio spectrum, and have limited bandwidth and sample rates. The new SDRs on the market, including the bladeRF, HackRF, and USRP offerings are purpose built for SDR experimentation. You might want an SDR to set up a cellular base station at Burning Man, scan Police and Fire radio channels, or to track ships.

[Taylor] breaks down the various specifications of each radio, and discusses the components used in each SDR in depth. In the end, the choice depends on what you want to do and how much you’re willing to spend. This breakdown should help you choose a hacker friendly SDR.