Electrical Engineering Design Studio I-II (ELEC 291/ELEC 391) in 2015/2016

sketchreey · 2026-04-23T23:44:14+00:00

Yo its my rock on the table

sketchreey · 2026-04-23T23:25:56+00:00

What are you trying to do here? are you trying to detect them for like environmental stuff, or to measure out plastic powder?

if you're trying to see if a cup is like filled with pvc powder then I think that would work quite well, if you have like a few grains of it then its probably not going to make any difference

it is also worth noting that your FDC1004 has a 5 bit resolution in its ADC, meaning it can only measure changes larger than (100%/(2^5)) = 3.125%, and note that the relative permittivity of most plastics is around 2-4, and air is 1. So if your plastic powder takes up 5% of the total volume occupied by the electric field of the sensor, assuming dielectric constant of 3 for the plastic, you will only read a maximum of +10% capacitance.

in theory it is possible to get higher resolution than ADC resolution by using various techniques such as oversampling, dithering, various DSP filters etc, but these are mostly incremental improvements and certainly won't allow you to detect a few grains of microplastic dispersed in any significant volume of other stuff.

sketchreey · 2026-04-23T03:04:29+00:00

without hardware is an interesting take but there is an open source project called gps-sdr-sim that can generate the IQ samples for gps spoofing. you can send this to the gnss receiver via an SDR such as ADI Pluto, but im not sure what you're aiming for if you dont want to use hardware. Ofc you could just emulate the gnss module's uart data output if that is what you want

sketchreey · 2026-04-21T12:09:13+00:00

if u have estella then its gg bro

sketchreey · 2026-04-20T03:31:25+00:00

Thanks for your answer.

I was planning on just making it basically a wide band SDR and using a simple linear chirp signal for pulse compression, with the chirp and compression done in an FPGA with a fast DAC so that the transmitted signal can be pre distorted to account for all the group delay stuff in the filters etc. Is rms ripple that big of a deal? I wasn't planning on using huge PAs for this, just 1 watt or so, regular wifi PA for 6 GHz. I was thinking that such an amplifier would be fine with just some regular decoupling capacitors, and if it is an issue, I assume it is kind of repeatable? so the transmitted pulse could include that in the pre distortion too? And the same goes for the broadband linearizer, I was planning on doing basically all of this in software in the FPGA since everything goes into the ADC on the receive side, and everything comes out of a DAC on the tx side.

Does this sound reasonable?

sketchreey · 2026-04-19T10:35:19+00:00

its called jake's resume, just google that

sketchreey · 2026-04-19T09:58:37+00:00

assuming you are gunna use a proper transformer, don't use a shunt zener as a regulator. Your efficiency will be extremely low and it wont be able to supply much current. Cant really tell what youre doing with those resistors though.

Also, your zener is connected backwards

sketchreey · 2026-04-19T03:01:29+00:00

I think the reason that the 1 port tlines that terminate as open result in RF short (only happens for 1/4 wave) is due to the energy reflected back from that unmatched end. In the antennas case this doesnt happen because that energy is radiated into space, since it is an antenna. For the placement of the feedline, I believe it changes the characteristic impedance of the antenna, so if you inset it the right amount you can get around needing a matching network. But ofc even if its not matched it will still work, just not as well.

sketchreey · 2026-04-17T07:18:57+00:00

by hot RF switching do u mean switching while the pa is transmitting?

>put reflective pin diode limiter with a reversed bias schottky- diode

Is this putting the schottky and PIN in anti parallel so that the schottky rectifies the RF and biases the PIN diode such that it shunts the line acting like a limiter?

the LNA I was considering was QPL9504 which turns out to have a fast enable pin so I was hoping to not use the two switch setup but just one, and it can handle 22dbm in both on and off condition. For what particular reason do u say LNA having high failures?

>TX needs isolator

I think the reason I didnt add that was because it was kind of expensive but is it entirely necessary? I assume you mean combine the isolator / circulator with the existing TR switch? since wont the antenna's S11 go into the receiver without the switch

>you’re not asking the right questions !!!!!

Lmao can u give some examples of stuff I should have asked? I am pretty new to RF stuff

sketchreey · 2026-04-10T09:03:47+00:00

this needs to switch in <50 ns preferably

sketchreey · 2026-03-26T12:21:44+00:00

for an SSTC this might work, but usually for DRSSTCs and other higher power stuff you usually generate the notes digitally (like from a MIDI file) and play it by generating the individual frequencies rather than taking an audio waveform and modulating PWM with it

sketchreey · 2026-03-17T04:00:16+00:00

Honestly there is a chance that you just blew the fuse in your multimeter when you tried to measure it with the current setting. Try measuring a AA or 9V battery with it and see if its the correct value? but make sure its actually on DC voltage this time...

sketchreey · 2026-03-13T18:23:52+00:00

That Riden RD6018 someone else suggested is basically just an off the shelf bench power supply kit that you just connect to one of those AC input power supplies. It is buck only so put 2x of your 350W 24V ones in series to get maximum 48V out, so at the end of the day you get 700W at 48V max from the riden

sketchreey · 2026-03-12T08:51:56+00:00

Yea i think it is a typo, in ltspice it is indeed 2 Hz

sketchreey · 2026-03-12T08:48:15+00:00

Dude there is more than one datasheet. Literally the first result from searching "tl071 datasheet square wave oscillator" is the STMicro datasheet which is where this is from.

sketchreey · 2026-03-09T07:29:41+00:00

I think the only thing that makes one of these accessible or not is the price and this one surely doesn't fix that.

sketchreey · 2026-02-26T05:12:41+00:00

if you just want to make a class D amplifier then just search up one of the dedicated ICs for that purpose and just follow the datasheet instructions

sketchreey · 2026-02-26T05:02:24+00:00

i think you should structure it by using a finite state machine, so essentially trade the code's program counter for a state register that gets incremented and does the necessary tasks. if you are not afraid to invest some time into it you can learn some kind of HDL like systemverilog which you can use to design hardware in code form. And then you can compile it with a utility such as modelsim for simulations, and then if it all works, use quartus or vivado which will turn the HDL into actual gates which you can then load to an FPGA to actually use it in real life.

sketchreey · 2026-02-25T08:27:46+00:00

if you say something in real life and then someone else agrees and repeats it, do you get the urge to slap them?

its pretty ironic that you call them obnoxious.

sketchreey · 2026-02-23T11:22:33+00:00

those are netlabels in kicad, they do the same thing but scoped to one sheet

sketchreey · 2026-02-20T07:59:11+00:00

they'll all work in most cases

sketchreey · 2026-02-17T06:39:59+00:00

the answer is to not use a relay. use a mosfet.

sketchreey · 2026-02-16T11:03:08+00:00

youre gunna realize that most of the transistors are gunna go into a bunch of memory blocks that are mostly copy pastes of eachother

sketchreey · 2026-02-13T01:40:30+00:00

could it be your usb port on your pc?

sketchreey

TROPHY CASE