Member Since: January 12, 2011

Country: United States

  • Even a quiz that rarely works due to high load is less annoying than captchas. Associating a negative experience with your brand is not a good idea.

    Also, what's the point of giving away money in $100 chunks? Smaller chunks would give the positive experience of winning to more people. They would also result in more orders, and probably also more spending beyond just what's given away.

  • Yes, it's the correct IC. It's from ST instead of On. I guess they abbreviate the markings so they can fit in the other stuff. The On datasheet, documents markings, but the ST datasheet doesn't.

  • I don't like how this chip cannot do PWM on its own. It doesn't have an oscillator, and when it counts to 0xFFF, it stops, shuts off outputs and needs to be reset via BLANK.
    I got it working by using a TLC555 in 50% duty cycle configuration to provide GSCLK and capacitive coupling one of the outputs to BLANK to reset the counter. I used a 4.7 kohm pullup at the output, a 2.2 nF capacitor between the output and GSCLK, and a 100 kohm pulldown on GSCLK. I also added diodes to clip the signal at GSCLK to the power supply rails; those are probably unnecessary. It works reliably once started, but I'm not recommending this except as a temporary hack. I'm planning to use a microcontroller to generate the necessary signals.

  • Because of the current regulation, you don't need any external resistors. Each TLC5940 output has its own current regulation, so brightness won't depend on the number of LEDs that are on. The only things you need to consider are the per channel current limit and the per chip power dissipation limit.

  • It is 120mA per channel with VCC > 3.6V and 60 mA per channel with VCC < 3.6 V. For larger currents, channels can be connected in parallel. There's also a power dissipation limit of 2456mW at TA < 25°C and less at higher temperatures.

  • The datasheet link is broken. There's no href attribute. Is this the same product as http://www.sparkfun.com/products/10259 , except that this is a 5m length? A datasheet is available there.

  • It would be a pain to modify this to control each LED individually. It's not worth it when you can instead get a LED strip which already allows this: http://www.sparkfun.com/products/10312

  • The strip consists of groups of 3 RGB LEDs which are connected in series. You can see that each group has 3 current limiting resistors, 1 for each colour. That's why you're only supposed to cut the strip at specified locations.
    If you cut at a different location, you would split apart a group. Then you would have to make somewhat inconvenient connections at that cut and add additional current limiting resistors.

No public wish lists :(