Recent content by Raisintoe

What I heard was that it cost up to $15 000 per audit that they do. Maybe it is a company-wide audit, I am not sure. And these audits happen up to four times a year. I really don't know much about UL.

I just found this on SparkFun, and thought I'd share it. This answers some common questions about FCC compliance: https://www.sparkfun.com/tutorials/398

Thanks, I remember hearing that UL cost $60 000 / year. That's good to know if that is optional. Although, as you explained, I wouldn't want to end up legally liable for someone's home burning down. That is what I remember learning in my research. Thank you for confirming that.

Christmas Lights would be another story, yes. They would be the 120 V AC Christmas Lights

One other question. I don't need my PE license to design and manufacture electronic products do I? As long as everything I do is contained within my business, and I am not offering an "Engineering Service" to anyone, then that is acceptable?

I guess I just won't sell mine, that's the answer. But mine uses the 3-pin DMX output, which is more common. It also has some status LEDs which would be helpful for someone trying to debug their settup. Mine was a first attempt to learn the business, and now I know it.

I only plan to sell within the United States. So FCC should be all I need.

Yes! Except mine is just like their ENTTEC Open DMX. Same thing.

This first device I made is a USB 2.0 - to - DMX interface device. So I have to get FCC certified for the 125 KHz caused by the DMX protocol, as well as the 240 MHz caused by the USB 2.0 protocol.

I have been developing some simple electronic devices to help with Animated Christmas Light displays. I was about to start selling professional versions of my devices, until I found out I am required to get them FCC certified. This costs about $2500 per design, which is completely outrageous...

Hmmm, I tied the gate directly to ground, and that didn't change the current through the 180 ohm resistor. I finally get the proper current (27.8mA) when I set the gate to negative 1 million volts!

OK, that's confusing. My next question is, why is the current so small? What do I have to do to increase the current?

I know it does, but why is it doing that? It is a p-channel MOSFET, why doesn't it turn on when a positive voltage is present? Also, when it does turn on, it has a very small current, (240uA in this LTSpice simulation).

I am new to using MOSFET transistors as load switches. Here, I am trying to trigger the P-channel MOSFET to run a current through the 180 ohm resistor. I can not figure out what I am doing wrong. It is supposed to turn on for a small moment (at the zero-crossing moment of the AC phase), then...

I want to fit the curve to three points, one point gives my Vi, the other two are my different V(t)s. I simplified to get: T = -t/[ln((V(t) - Vf)/(Hi - Hf))]. Now I can set two equations equal to each other: -ta/[ln((V(ta) - Vf)/(Hi - Hf))] = -tb/[ln((V(tb) - Vf)/(Hi - Hf))]. This simplified to...