Member Since: December 18, 2011

Country: United States

  • The biggest EOL problems I’ve had are with low-cost through-hole power FETs. They seem to be dropping like flies. I was changing the FETs for my course every year! Some of the packages had very short leads and would not stay firmly in the breadboards.

    I finally decided to have the students solder SOT23 FETs to a breakout board, so that we could use the same part numbers each year and so that the header pins were long enough to stay in the breadboards.

  • Red, blue, and yellow are not subtractive primaries: cyan, magenta, and yellow are. Your subtractive Venn diagram is misleading.

  • Asking people about their ages and what they studied in school/college would be interesting. Jameco’s similar survey a few years indicated that almost all their hobbyists were retirement age.

    As for Makerspaces, I agree that cost and accessibility are the main barriers for me. The closest makerspace is close enough, but too expensive ($45/month to get access to hand tools no better than I have at home, $90 a month to get 4 hours/week of reservable time on the good tools (laser cutter, 3D printer), $120 a month to get 8 hours/week (adding the Shopbot to the allowed tools), $240 a month to get 12 hours/week). If I had a project that actually used that much of the equipment time, the prices would be good (under $6 an hour), but I tend to have no time for most of the year, then I want a chunk of equipment time all at once, so the hours/week subscription model doesn’t make much sense for me.

    The local community college has a makerspace that is $145/month ($105/month if you take two of their training courses). There is $20 worth of materials included in that fee. It is a 50-minute bike ride away, so I would be hard pressed to go there often, and only 4 hours a month of laser time and 10 hours a month of 3D printer time are guaranteed in the membership.

    Although I would probably like the camaraderie of a makerspace, I have a hard time justifying the expense, which would buy me a lot of tools and parts that I could use without reserving them a week in advance.

  • You only have zip ties holding the stepper motors in place?? Those screw holes on the face of the stepper motor are there for a reason—to keep the motor body from moving instead of the shaft. There should be plates screwed to the motor and slotted into the support to take the reaction torque.

  • Why such high temperatures? Only the bottom two temperatures seem useful for electronics soldering. Is this tool intended for jewelers doing silver soldering?

    The round body looks like a roll-off-the-bench burn waiting to happen—is there a stand with a cage sold separately?

  • Incidentally, one can get very nice I vs. V curves with an Analog Discovery 2 and a resistor, up to the power output limits (5V and 700mA using the power supply or about 100mA using the function generator). The function generator or power supply can be driven (slowly) with a triangular wave, so the I-vs-V curve can be collected in one pass using the two differential scope channels. I’ve used this technique for DC characterization of several parts, including LEDs.

  • A load for testing power supplies is going to get hot somewhere—it’s function is to dissipate a controlled amount of power. The linear solution here makes more sense than a switched solution, because a lot of power-supply testing is looking at how much ripple it produces and introducing more ripple from the adjustable load would hide that. Also, one might want to look at the power-supply response to step increases in current, which an inductive load is not capable of emulating.

    That said, I don’t see the attractiveness of the PSoC line of microcontrollers here—the analog circuitry is just being used to compensate for the inadequate resolution of the DAC and ADC. A KL26, such as in the Teensy LC board, would be a simpler solution.

  • Isn’t the button a little small for a foot pedal? Compare with pedals like or

    I see that some guitar effects pedals do just use a small switch like the one here. Guitar players, how well does that work, compared to the bigger pedals?

  • This board looks like it is over-engineered to me. Using a $5 accelerometer when a 3¢ vibration switch would do seems a little strange (unless you are a company that makes accelerometers).

    I tried designing an analog circuit that would handle more output power and work over a wider output range on a smaller standby power budget:

    I’ve not tried building it, though (too many SMD parts). If anyone tries it, please leave a comment on my blog!

  • If you want really light weight, and don’t mind disposable batteries, you get about the same energy from a #10 zinc-air battery that weighs 0.3g (100mAH at 1.4v).

No public wish lists :(