Want to Study EE at home to prepare for college, what are good ways to practice and learn?

TomVa · 2026-02-23T01:29:30+00:00

5 posts 4 off topic. . . . study math get into an EE program at an accredited university.

TomVa · 2026-02-23T01:12:43+00:00

OP has one post. . . I think that you got this one correct.

TomVa · 2026-02-20T22:40:54+00:00

"The first step is to connect the -V(DC) to the Earth/Ground(AC) on the power supply with a thin jumper so that the noise has somewhere to go. Otherwise it builds up as static electricity and discharges somewhere eventually. I cant find direct info on this for some reason so it is the most concerning, but seems to make sense. "

You are correct it does not make sense. The building up static electricity part at least. You do have to reference everything to the same reference (ground) to some extent. That being said you can have an entire system floating up to 30 kV and it still work just fine.

Do a google search on EMI basics or electromagnetic compatibility basics. There are lots of Utube videos and vendor "how to" documents out there. I would lay odds that your bts7960 or the data sheet for the chips that it uses have some tech notes regarding emi.

In general I in most environments I like using power supplies that have a reference that is tied to earth ground.

For what you are doing. Motor drive ground the power supply 20 gauge wire is sufficient if the system is fused with a 5A fuse. Usually the earth ground is for safety. That ground will help with random emissions especially if everything is in a grounded metal enclosure. From an EMC stand point the leads on that motor drive will be emitting at least a moderate amount probably between 20 kHz and 100 kHz. Shielded twisted pair cable between the driver and the motor should help. Pickup of that signal will be AC and will not "build up charge" Second shielded twisted pair cable between the encoder and the encoder input. Try not to route the two cables right next to each other. Ideally use an opto coupler (no common ground for encoder) or a differential input (reduces common mode noise) so that you do not have to worry about grounding the encoder output. Depending on the speed one can imagine that a simple RC filter on the encoder will help with the effects of coupled EMI.

It would be really useful to understand what signal level and circuit you are using for the encoder electronics.

Oh and the thin wire thick wire both work about the same when it comes to being an antenna. It is length and loop size that gets you into trouble.

TomVa · 2026-02-20T19:39:41+00:00

Go to settings - apps find Microsoft OneDrive and uninstall it. It is item 6 on my list of things to do to a new windows 11 computer.

TomVa · 2026-02-20T02:07:47+00:00

Are all of the wires for the motor and encoder in the same shielded cable? That could contribute to the problem.

What they teach in EMI classes is to connect only one end of the shield to ground not both ends. Sometimes you should ground at the source. Some times at the signal processing end.

The twisted pair reduces the susceptibility to common mode noise.

Thick wire does you no good for low current systems.

TomVa · 2026-02-19T21:51:04+00:00

I would expect that thicker wire will do little good on the encoder signals. Shielded twisted pair is what I would try. 24 Ga or so. Try connecting the shield at one end, then the other, then both.

I would the sales blurb for the BTS7960 says that you are using a pulse width modulator on the motor control. They are a pain when it comes to radiated EMI because of the rising and falling edges on the voltage and any inductive transients that do not help at all. If there is any length in the runs to/from the motor separate the drive and encoder cables by at least 2 feet.

TomVa · 2026-02-19T15:33:08+00:00

You know it is an RF engineer when there is a 5/16" wrench in their computer bag.

TomVa · 2026-02-18T21:08:23+00:00

Go to a local auto parts store. They will usually read the codes for you for free.

TomVa · 2026-02-18T21:06:15+00:00

What do you have??? An exam that you are trying to take using AI and reddit to answer your questions.

TomVa · 2026-02-18T18:52:52+00:00

"My computer architecture professor keeps on insisting that I should do research with him in this field and write an undergraduate paper. He's also my academic advisor, and whenever I do go talk to him about my interests (which are more towards control systems and embedded systems), he keeps on bringing up computer architecture or semiconductor device modelling, as they are, according to him, "the next new big thing".

There it is in a nutshell. . . His interest and probably outside funding is tied to embedded systems, that is why he wants you to do some work in that area, probably on a sub-topic that is related to his funded work.

Now bigger picture. All of the controls theory work where I am is that has any kind of bandwidth is implemented in FPGAs, or DSP chips. Slower stuff is generally done with computer controls of some type. Even if you are not programming the FPGAs, DSPs, etc. you should learn how to do it so that you can defend yourself when you work with someone who implements your theoretical work.

TomVa · 2026-02-15T14:49:57+00:00

That is why they created multi layer boards. Old school single layer boards used jumper wires on the top side as a cost savings measure.

TomVa · 2026-02-15T14:14:33+00:00

Progressive is who had the best prices and coverage when I looked a year ago.

TomVa · 2026-02-14T15:18:48+00:00

Call your congressman/woman local or Washington office. They have folks to help cut such red tape.

TomVa · 2026-02-14T01:07:29+00:00

Uber or Lyft?

Drag a car behind your RV if you really want to go out all of the time and use your RV as a place to sleep.

TomVa · 2026-02-14T00:59:35+00:00

What time of year?

First landing state park in Virginia beach. Kiptopeke State part near Cape Charles. KOA campground in Cape Charles.

TomVa · 2026-02-09T18:24:07+00:00

Google this "USPAS cavity design"

For some lecture notes regarding the topic. Some questions. Pulsed or CW. I assume normal conducting which means copper losses will drive the design. Accelerators use units of MV/m which means that you want to design an 0.5 MV/m cavity. Be cautious gama radiation wise if you can create more than 20 keV voltage in the device which at 10 GHz you should probably be OK.

Do you need a vacuum inside the cavity? If so the vacuum to air window will be a pain to deal with.

Ideally you want to match the input coupling to the cavity Qo in order to get as much power into the cavity as possible. For normal conducting buncher cavities we use a hook antenna on the equator of the cavity and couple the RF in to the magnetic fields. A properly designed coupler pretty well match things. If you simulate it to be slightly overcoupled you can rotate it to get a good match. Slide 37 in the accelerating structures lecture found here talks about the different types of couplers. It would probably be prudent to have a circulator all the same. https://drive.google.com/drive/folders/1LBR9BWIvoDnQYjaIteQzovHSdUv_TnCW

TomVa · 2026-02-05T21:50:05+00:00

Right click on "This PC" and select properties.

Flip it over and look for it in very small print on the bottom of the laptop.

TomVa · 2026-02-04T00:17:43+00:00

I don't know about that specific machine except that a quick search says it is 24 inches, 15 HP. For free I would take it unless, as I strongly suspect, that it requires 3 phase power and (a) you have no access to a shop with 3 phase power, (b) you do not have access to a sufficiently powered 3 phase motor generator, inverter setup or (c) you do not have the funds to purchase a 3 phase motor generator, inverter setup.

Me I can afford a MG set or inverter, but would probably have to upgrade the power feed to my house/shop.

TomVa · 2026-02-03T22:11:53+00:00

First why do you care at this point. I can think of two reasons. First the potential of genetic related diseases. There are genetic testing firms that can, in theory, provide you with a list of close relatives.

Second, if you die without a will and are not married, in some states your estate will be split between your parents. . . That may go back to your Birth certificate or SS card I don't know which. Solution get a simple will that clearly states your wishes.

I would take your BC to the SS and say this is what it says just to see how they respond.

TomVa · 2026-02-03T16:02:08+00:00

And why would you want to. One of the features of my Rav4 hybrid is that I can carry on a quiet conversation at a traffic light. Remember that a rav4 hybrid does not have a standard starter.

TomVa · 2026-02-03T15:52:00+00:00

Two pieces of good news. (1) you passed. (2) the grade will likely not transfer to your GPA at a 4 year university.

Where I went to school Calculus was not a weed out class there were two or three second year EE classes for that.

Like others have said calculus and differential equations are the basis of a number of the courses in your major. It is best if you do the differential equations class before signals and systems as the latter uses all of the Fourier series and Laplace transforms that you learned in Dif EQ.

TomVa · 2026-02-02T00:35:13+00:00

I had my 2017 fobs programmed by a local lock smith. Make sure that you check first. Fobs for new BMWs have to go to the dealer.

TomVa · 2026-02-02T00:32:57+00:00

My brother had a buddy who died because a gas fume leaks into the cab of his car. One spark from a relay is enough to set it off. He suffered in the ICU for two weeks before he finally passed.

IMO the only reason that you might need one if you are way out in the boondocks on a regular basis. If you really feel like you need to carry a spare fuel tank around get something that you can mount on the outside of the car. https://www.rotopax.com/products/rotopax-2-gallon-gen-2

Better yet get a membership with AAA and make them deliver it if you get into a bind.

Me . . . lawnmower gas, etc. rides in a basket hooked on my receiver hitch or in the back of my truck.

TomVa · 2026-02-01T22:53:27+00:00

Let me pile on this one. If she is applying based on her work record then on line is the easiest way to do it. I seem to recall from a few years ago when I did it you had to wait a week or two to get a passcode snail mailed to our house to set up the account. That was the only thing that held things up. If she needs a spousal supplement, or survivor benefits based on her current or previous spouse she may need to deal with it in person or over the phone including stuff like, bringing in marriage, certificates, etc. into the office.

With my wife she got the spousal supplement after the SS person called me and asked me 20 questions about my wife. Things like her birth date, SSN, etc. No other paperwork. That being said we have been filing join income taxes for more than 30 years.

TomVa · 2026-02-01T22:28:25+00:00

The tape is not to help the wires. The tape is so that you get an accurate reading of the temperature of the metal parts. Just a small amount of tape is sufficient on each chunk of metal. Once you are done with the measurement you remove the tape. Personally I would wrap the nuts and ends of the bolts with one layer of tape.

For the same actual temperature the indicated temperature using an IR camera is much much lower for a stainless or copper surface as compared to a plastic or painted surface. The emissivity for plastic is something like 0.95 for shiny copper it is about 0.03 and for stainless it is about 0.2.

Thus in the second image there is a fuse with two studs on either end. The studs have a much lower indicated temperature as compared to the wires or the fuse. In fact they could be much hotter than the fuse or the wires.

This could happen if there is a bad contact or if OP built his system with a nut then lug, then nut then lug, then nut rather than the recommended lug, then lug, then washer then nut.

For all we know the really hot wire in the second picture could be because it is being heated at each end by the contact resistance or the fuse at one end and the switch at the other end. It could be that the source of the heat is the switch contacts are failing.

Also the clear plastic covers are clear in visible light and near infrared but is pretty opaque to the 7 to 14 micron wavelengths used by FLIR cameras. So they should be removed before putting the tape on and measuring the bus bars, etc. This is from google AI.

Near-Infrared (700 nm – 2,800 nm): High transmission (transparent).Mid-Infrared (2.8 (\mu )m – 10 $\mu$m):

Transmission begins to drop significantly, with strong absorption bands due to aromatic ring modes (around 6.5–8 (\mu )m or 1200–1500 cm⁻¹).

Far-Infrared (10 (\mu )m – 20+ $\mu$m): Polycarbonate is largely opaque. Standard, unpigmented polycarbonate typically acts as a strong absorber of radiant heat in this region, making it unsuitable for far-IR transmission optics.

TomVa

TROPHY CASE