Electrical Engineering

PSpice Schematic help!!!

Mon, 29 Jan 2007 05:04:01 GMT

Hi. I'm drawing a Thermistor on PSpice Schematic to show a figure of the Thermistor for the lab write up but I am having trouble drawing the current "i" on PSpice Schematic. Could you help me out and tell me how to insert the current on my schematic? This is only the second time I have ever used PSpice Schematic so I really don't know what I am doing. Also is there a way to assign a positive and negative side to a resistor because I can't figure that out either. Thanks for your help!!!

Component Failures X-Posted

Thu, 03 Aug 2006 20:38:48 GMT

I am driving a 2n7000 transistor in a TO-92 package. I am having random seeming failures of these parts on new boards. I am not sure why. Are they more ESD sensitive than other TO-92 transistors? The circuit is an audio circuit where we are using the 2n7000 to block a low voltage audio signal. The base is driven directly off an 8051 series controller with a pull up resistor its value is 100k.

Any ideas on what would make transistors randomly fail would be appreciated. Or any good links on component failure. We have crappy ESD control and antique test equipment (one oscilloscope that is a Tektronix 2247A, I think) so I do not expect to be able to find anything as fast as an ESD discharge.

Just looking for understanding. Thanks in advance.

IBGT's in PSIM and Multisim7

Mon, 17 Jul 2006 21:08:00 GMT

Hello!

Doing a project for this class which is becoming completely self taught. Design an active power filter for load compensation.

So far I think I'm doing okay. I have a the demo version of PSIM, which has IGBT's that look the way I am familiar with them looking:

(not that entire thing, but the switch in parralell with the diode)

The thing is that the PSIM demo wont run a simulation with a certain amount of elements and I havent been able to get ahold of anyone at the company to buy it. So I think im going to use Multisim 7 which I have a full version of.

Multisim 7 shows the IGBT component as something similar to:

My question:

Are these two things equivelent?

Does anyone have any suggestions to make this work if they are not?

Thank you!!!
Crystal

x-posted

IGBT's in PSIM and Multisim 7

Mon, 17 Jul 2006 20:30:19 GMT

Mon, 17 Jul 2006 02:43:52 GMT

Hello guys,

Just a quick...legal minding note..

Does anyone have a full version of PSIM that I could maybe... borrow?

:)

xposted

Audio X-Posted

Thu, 06 Jul 2006 13:31:04 GMT

My boss wants to incorporate audio through PC style speakers into our new product. I know nothing to speak of about audio. He has a design done by someone else that he is using that sounds;well, not really acceptable in my opinion but he thinks it is OK.

It is using a TS942 Op-amp as a driving amp and it drives into a 5k ohm load then into the speakers. The Op-amp specs a minimum load of 5k. I tried to push for a more application specific amp but he does not want to use surface mount.

I have seen that the 3.5mm phono jack usually has 16 Ohm head phones attached to it. Can I assume that the PC speakers have a 16 Ohm input impedance? I have asked RCA and Jensen about their wireless PC speaker system's input impedance. Jensen said their system is no longer in production and questions like that cannot be supported. RCA has not answered the question yet.

Finally does anyone know any good books or preferably good web sites I can visit to quickly get up to speed on this subject? I am not looking for home stereo quality sound but basic PC sound would be a huge improvement!

Thanks in advance!

Active Power Filters

Wed, 14 Jun 2006 19:36:01 GMT

Hi guys,

I'm an EE student at Wayne State in Detroit and taking a power electronics course. I know very little about active power filters and our final project is to design one.

Could anyone recommend any good websites or books to learn about this topic? I keep finding technical papers that a little over my head, but I did come across a book called "The Active Filter Cookbook" by Donald E. Lancaster...anyone heard of it?

Here's the link btw:
http://www.amazon.com/gp/product/075062986X/ref=olp_product_details/104-8931818-7847145?%5Fencoding=UTF8&v=glance&n=283155

Any help or suggestions are appreaciated :)

Thanks!
Crystal

x-posted

New Community

Thu, 20 Apr 2006 17:28:36 GMT

X-Posted
Shameless plug for a new community. I hope to have some great interest sparked:

http://community.livejournal.com/electricvehicle/

Thank you

Op-Amps?

Fri, 28 Oct 2005 01:44:25 GMT

Could someone suggest a book to buy or a website to read, so that I can understand Op-Amps?

I've tried two Circuits books, and I still don't get it. Seems like a bunch of hocus-pocus, and being a protoengineer, I'm not big on the hocus-pocus :)

Mon, 17 Oct 2005 07:33:26 GMT

I am dabbling in DSP and am trying to find a Compander Algorithm. Do any of you chaps know where I could find one in C? Google is failing me :( Any links or advice as to how to implent this (or similar Automatic Gain Control type algorithms) would be much appreciated. Thank you!
========================
Here's some helpful definitions:
Compander
Combination of a compressor and expander. The peaks signal levels above the upper threshold are compressed, while lower level signals above the lower threshold are expanded.

Compressor
Keeps the level of the signal within a specific dynamic range, using a technique called 'gain reduction'. The objective of a compressor is to make sure that the signal level does not go beyond a desired level, thus restricting the dynamic range.

Expander
Opposite of a compressor, with opposite input/output ratios. This effect is often used to recover the full dynamic range of a compresses signal. Also useful for reducing noise in tape recording and wireless systems by increasing the level of the audio signal relative to low-level noise beyond a low threshold.

Noise Gate - Downward Expander
Reduces the amount of gain below a certain threshold to reduce or eliminate noise produced when no audio signal is present, while still allowing the signal to pass through. This is useful after processing multiple audio effects that can introduce noise above the noise floor of the AD1819a DACs.

from the dumb people

Mon, 11 Jul 2005 20:56:06 GMT

hey smart people, i'm not especially smart in EE, (i was an IE for a while). i'd just like to ask, if anyone knows,

do appliances still use electricity if they are still plugged in when turned off? like if i keep my computer plugged in, but it is off, does it still eat up electricity?

thanks for listening to my question :D

Cheap DAQ? X-Posted

Fri, 17 Jun 2005 14:14:18 GMT

Does anybody know where I could buy a cheap DAQ?
I need to have either serial or USB communication to my PC so I can present the data in a respectable way. I need about 5 or 6 lines I could use 4 and take 2 sets of data, prefer not to have to.
I also need it to be able to measure up to about 20 V DC or AC. It can be really slow. If I take one measurement a second it will be ok> I need it mainly to make charge rate charts and such. I know I could buy an Agilent one for about 1500 plus the cards. If I cannot buy one for a couple hundred or so I will build one.
Thanks in advance!

conference room 4

Thu, 12 May 2005 13:18:53 GMT

Here's an interesting engineering news and blogspace I came across this morning...

CR4

Interships...

Fri, 28 Jan 2005 16:20:22 GMT

Hey everyone,
I am looking for an internship this summer with biomedical research. I'm a Junior in EE at Purdue University. Unfortunately, everyone here at the job fairs, etc are just looking for full time positions. Even when I talk to recruiters at the internship job fair!! I know there are many companies that do biomedical research with times composed of BME, EE, ME, CHME..... When I talk to recruiters (after researching their companies) they have no clue what I am talking about, even though I can tell them projects that their company is working on similar to what I am wanting to do. Maybe I am just looking in the wrong area or at the wrong companies. Any suggestions would be much appreciated.

Thu, 16 Dec 2004 18:34:03 GMT

Hi, I'm new to this community. I'm a student at Kingston U in London. I was wondering, does anyone know what the equation is to calculate drift current? For some reason my text book doesn't actually list an equation. hmm.

Thanks!

status/introduction

Thu, 02 Dec 2004 21:06:23 GMT

i was wondering on what the deal is with most of the members of the community... are most of you guys students/in school? if not what kinda work do you do? where do you work? how long, etc?

ive been out of school for about 3 years, i work for a company designing memory chips for SOC design... theres not really that many jobs in the area... besides working for the big defense contractors... any cool job ya need an advanced degree for the most part... i am more into mathematical stuff, like control, and more in depth stuff with devices, but i dont really get to work on anything like that...

Inductor Help Please

Tue, 23 Nov 2004 17:40:07 GMT

Hello

I am stuck on an inductor problem and was wondering if anyone could give me some advice here.. What I am trying to do is find the equivalent inductance looking into terminals A and B. (we are working with DC circuits only if it makes a difference)

I was told that inductors combine like resistors, so I was thinking that since there is a short, the only inductors that need to be considered are L1 and L2, making 4H + 6H = 10H. Is that how these should be treated, or do I need to consider L3, L4, L5 and L6? And then if you did have to include L3-6, can you add L4 and L5, and then do a delta-wye transformation on L3, L6 and (L4+L5) just like resistors? Ive never heard of delta-wye transformations with anything but resistors, even if it dosent apply in this instance, is it possible in other applications?
(schematic hidden behind the cut)

Thanks!

Sun, 10 Oct 2004 17:13:55 GMT

A mathematician, a psychologist and an economist commissioned by British Gas have finally put into mathematical terms what we all knew: that things don't just go wrong, they do so at the most annoying moment.The formula, ((U+C+I) x (10-S))/20 x A x 1/(1-sin(F/10)), indicates that to beat Murphy's Law (a.k.a. Sod's Law) you need to change one of the parameter: U for urgency, C for complexity, I for importance, S for skill, F for frequency and A for aggravation. Or in the researchers' own words: "If you haven't got the skill to do something important, leave it alone. If something is urgent or complex, find a simple way to do it. If something going wrong will particularly aggravate you, make certain you know how to do it." Don't you like it when maths back up common sense ?

Fri, 24 Sep 2004 07:33:43 GMT

Here's a fun Lazer/Optics flash game.

http://laser.narr.as/laser.swf

x-posted

Sat, 28 Aug 2004 05:09:10 GMT

Hey

My name is Anya and I am a senior EE at GA Tech graduating this December. I am interested in finding a job related to RF circuit/antenna design or communications. I have been using www.collegegrad.com, careerbuilder and yahoo hot jobs to find positions along with searching through various campus interviews. The only problem is that i have NO TIME to look for jobs. I spend so many hours on campus trying to complete projects and labs...and by the time i get home i'm too tired to do anything...and i know i should be spending at least 2 hours a day searching if i want to find something before I graduate.

sorry. i probably sound a little jaded. it's been a reeeally long week. i spent 8 hours in my Analog circuits lab frustrated and hungry

Wed, 25 Aug 2004 20:13:25 GMT

Hello everyone. I'm a highschool senior starting college apps. EE is my top choice for majors on all of them. I've read about it, done breadboarding :P, and read some more but I still feel like i know nothig about EE. I guess I need a more personal description than what I can get reading news articles and course descriptions so....What the heck do you guys do? And do you enjoy it (I have found out that this is 1894320303843x more important than the $$$$)?

Thanks

(I never do this but I might x-post to engineering)

any interesting projects?

Tue, 13 Jul 2004 05:29:05 GMT

What are people working on these days? Anyone have some good homebrew how-to-get-started PIC ideas? :)

Integrated Circuits, once again :)

Wed, 12 May 2004 20:12:12 GMT

Hey all.

So, IMX Technology currently has 2 auctions up on ebay and a bunch of things in the store.

However, we still have a ton of ICs and I'm still trying to get a better handle on what will sell, for how much, and to whom...We've been trying to find non-ebay buyers (or distributors who will sell our stuff on consignment), to no avail. I have to admit, the ebay thing is kind of fun, though. ;)

I talked to a distributor a while back who said some of the parts he'd gotten from us in a lot that he'd purchased on ebay--in particular, parts made by Intel and Brooktree--could be sold for a lot more. He said he could get anywhere between $5-$50 for them. (He was supposed to sell some things for us on consignment, but he disappeared. Grrr.) Is this possible? And how? I don't want to try selling them on ebay if I can do better, but we haven't found many other options. If you were selling these items in an ebay store, what would you price them at? (If you need more specs I can provide them.)

If you could take a look at the store and let me know if the prices are completely unreasonable, or TOO reasonable, or if the parts just won't sell at all and should be scrapped...any input at all would be much appreciated!

THANK YOU!! :)

(x-posted)

Wed, 28 Apr 2004 05:18:51 GMT

Hi!

I'm a first time poster but I watch this community, and I'm just starting out as an Electrical Engineer.

I have a final tomorrow in circuits 1, and I'm having a little problem figuring out one of the examples

I know the circuit should come out to be a second order equation, but I cant seem to figure out how to get around the dependent voltage source.

Anyone an ECE here that can help?

It's problem 3 on here:

http://neuron.eng.wayne.edu/ECE330/quizzes/final.pdf

Any help is appreaciated!!!!
Thanks!

Yet another new member

Sun, 25 Apr 2004 21:12:16 GMT

Hey I'm Bill, a student in ECE at the University of Illinois. I offer my knowlege, but as a freshman who hasn't taken much past intro logic and circuits classes, don't expect a whole lot. I hope to learn a few things here.