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Member #466449

Member Since: September 2, 2013

Country: Argentina

  • Ignore my last comment on this part. I’ve got a better idea.

    I’m going to make a switching power supply that plugs into the mains, but I need some help:

    • This IC can’t be wired straight to the mains, because its maximum supply voltage is 40 volts. But what if I wire it up like this? Would that work?

      bridge rectifier – resistor¹ – 400V cap² – zener diode – 16V cap³ – MC34063

    basically, a transformerless power supply, for low currents it should work

    ¹ To limit inrush current while the capacitor charges up. What would be a good value to use? 10 ohms? 22? 47? 100?

    ² In my country we have 220V mains, so I can’t just use a 200V capacitor. Actually I think any capacitor rated for 330V or higher would be ok, but you never know, one of these days I could get a voltage spike and, after taking everything apart, a blast of blue smoke.

    ³ I will actually use a cap rated for at least twice the zener diode’s voltage. So obviously I won’t use a 16V cap and a 12V zener.

    • If I use an external MOSFET, can I connect it to the MC34063 and switch (already rectified and filtered) mains electricity? If so, can you recommend a part number for a MOSFET that can handle 400V?

    Sorry for the long comment. Please answer as soon as possible. I don’t need this for next week or anything like that, but the sooner the better.

    Thank you.

  • Flyback diodes can be useful to avoid the 20V, 50V or probably even 100V spikes due to the motor’s inductance. As you most likely know, they are meant to be wired in the opposite way as the power supply (i.e. positive to cathode and negative to anode).

    Now the problem is, if you want to reverse the motor’s rotation, you have to reverse the polarity. If you reversed the polarity, the diode wouldn’t be wired in the correct way anymore, and would instead short out the power supply anytime the motor was on.

    And if your power supply was not current limited (e.g. LiPo batteries without protection circuitry) you would most likely set things on fire.

  • Maybe you can implement an automated script, that if someone posts 3 or more identical comments, it would disable that user’s account. After say 24 hours or even better 3 days, it should re-enable it, but if he/she keeps spamming it should disable it permanently.

    I say 3 or more and not just 2 because some pairs of products, such as the Cool White and Warm White 3W LEDs (COM-13105 and COM-13104 respectively) both have the same error in the description or somewhere else.

    Or maybe just use a captcha-like verification code when registering an account. Or both. Even though that would be annoying for legitimate users, it would hopefully reduce spam.

    Anyway, the main reason why I posted the first comment was to get an answer on the size and price of each of the solar panels you used, so could you please answer that question? Thanks ;)

  • The spam comment I was talking about got deleted. But now as I type this there is another one! Thanks for the suggestion, I reported it already.

  • So, each panel generates 327 Watts, but how much did they cost and how big are they? Because you guys sell a 18x22cm (~0.04m²) panel that produces 5.2W and costs $44.95, so at that rate a 327W would most likely be about 60 times as big (maybe 1.5m on each side?) and cost about $2800. Please tell me I’m wrong.

    On a completely unrelated note, can you please delete “spam bot” accounts such as Member #644538, who commented here, and about 10 others I have seen in the past but obviously can’t remember their IDs? It pisses me off when I want to read comments in your blog posts and I see spam.

    Oh, and if you don’t delete the accounts, but those users ever buy something from the site, which I highly doubt, send them something completely different to what they bought, preferably damaged parts, and ignore customer service calls/emails from them. lol, just kidding, but actually, why not? ;)

  • I tried this under Firefox, and it looks kind of buggy with what seems like redrawing problems. Under Chrome, however, it works pretty well (sometimes it lags but it might be my computer). I find this annoying because I use Firefox most of the time, so it would be great if you could fix that.

  • They’re carrying them now!

    Switch: https://www.sparkfun.com/products/13253

    Breakout board: https://www.sparkfun.com/products/13098

  • This product has been retired from our catalog and is no longer for sale. This page is made available for those looking for datasheets and the simply curious.

    Which datasheet? You never got a datasheet for this product ;)

  • That’s funny because it’s currently out of stock and there is no ETA.

  • Even if you could connect ONE of these to a computer via serial, you’d be very limited in terms of either refresh rate or color depth.

    At 115200 baud, if you were driving it at 3-bit color depth (where you only have 7 basic colors, that is, blue, green, cyan, red, violet, yellow and white), you’d get 37.5 Hz refresh rate, which is pretty good, however you don’t use the full color capabilities of the matrix; but try to use even 12-bit color depth and the refresh rate will drop dramatically to ~9.4 Hz, which sucks, because the display would flicker too badly.

    Try to do something similar to what’s suggested on the tutorial recommended above, you’ll actually need a micro (specifically a Teensy 3.1) but as far as I know it’s the only way to hook one up to a computer.

No public wish lists :(