spread spectrum cheating

Started by John Larkin in sci.electronics.design2 weeks ago 57 replies

We make a bunch of boxes that go into a semi fab tool. One measures an optical waveform and shoots it to a bigger box, over three twisted pairs...

We make a bunch of boxes that go into a semi fab tool. One measures an optical waveform and shoots it to a bigger box, over three twisted pairs (clock, data, data) using shielded RJ45 ethernet type stuff. When we originally did it, they told us we were exempt from ROHS and EMI standards, but now we aren't. ROHS is no big deal, but the little box makes a continuous 62 MHz clock, differential...


TIA/EIA 568 A vs. B

Started by Ricky in sci.electronics.design2 weeks ago 30 replies

I was looking up the wiring diagrams for Ethernet cables and found TIA/EIA 568A and TIA/EIA 568B wiring diagrams. They seem to be wired the same,...

I was looking up the wiring diagrams for Ethernet cables and found TIA/EIA 568A and TIA/EIA 568B wiring diagrams. They seem to be wired the same, but for the colors used. They swap green and orange. At first I thought I was looking at a crossover cable, but no, they clearly say they should be connected the same at each end. One uses orange and green pairs, while the other uses g


Weird/smelly problem with Skybuck's DreamPC2006 and CPU fan not spinning

Started by skybuck2000 in sci.electronics.design1 year ago 30 replies

I did the following: 1. Replaced winfast motherboard with backup winfast motherboard. The backup motherboard is same model yet strangely...

I did the following: 1. Replaced winfast motherboard with backup winfast motherboard. The backup motherboard is same model yet strangely enough missing one ethernet port, it only has one, while the other has two, also firewire pins missing but ok. 2. Put some new artic silver 5 on the cpu. 3. Struggled to get the scythe ninja heatsink on it, pulled it off then put it back on ? I know thi...


Gigabit PoE - component solutions?

Started by Clifford Heath in sci.electronics.design3 years ago 2 replies

I need a inexpensive (i.e. not packaged) solution to delivering clean Power over Ethernet at gigabit rates. Yes, I know that balun imbalance...

I need a inexpensive (i.e. not packaged) solution to delivering clean Power over Ethernet at gigabit rates. Yes, I know that balun imbalance will limit how clean it can be - but I'd still rather not bring unnecessary noise into the remote (box (a radio). I don't want to buy a commercial packaged solution for injecting power, because most don't care at all about noise (I've measured *vol...


pcb signal integrity check

Started by Anonymous in sci.electronics.design3 years ago

This is the control board of my alternator simulator. I think we are getting close to receiving a purchase...

This is the control board of my alternator simulator. I think we are getting close to receiving a purchase order! https://www.dropbox.com/s/wvyxwlwzou3thh9/T901_22.JPG?raw=1 It has high power, relay drivers, uP, FPGA, dram, ethernet, USB. It goes close to the front panel in this: https://www.dropbox.com/s/71whot11i312y63/P900_3d_3.jpg?raw=1 My homework assignment is to do the s...


Ethernet RJ45 jack - what do the transformer centre taps do?

Started by Peter in sci.electronics.design3 years ago 6 replies

This is a common type of jack with integrated magnetics http://www.kosmodrom.com.ua/pdf/HR911105A.pdf It connects the txf centre taps via...

This is a common type of jack with integrated magnetics http://www.kosmodrom.com.ua/pdf/HR911105A.pdf It connects the txf centre taps via 75R resistors to a 1000pf cap which then (pin 8) goes to the circuit ground. What does this do? There are versions of the 10/100 jack which don't use the centre taps at all e.g. http://peter-ftp.co.uk/screenshots/20191119201261014.jpg


I2C cable

Started by Winfield Hill in sci.electronics.design4 years ago 46 replies

We need a 1-meter length of 100kHz (or slower) I2C onnection. It'd be nice to use a pre-made cable: micro-USB, 4-wire RJ11, or RJ45...

We need a 1-meter length of 100kHz (or slower) I2C onnection. It'd be nice to use a pre-made cable: micro-USB, 4-wire RJ11, or RJ45 ethernet. Some considerations: SCL and SDA crosstalk(?), high ground capacitance. Also need 3.3V, Gnd. Micro-USB: SCL and SDA twisted together, bad? RJ11: flat, SCL and SDA on outside lines? RJ45: SCL and SDA shielded from each other. -- Thanks, ...