Search found 71 matches

by rosborne
Tue Aug 17, 2004 5:15 am
Forum: General Discussion
Topic: Current source
Replies: 64
Views: 13266

Current source

Does anyone know of a way to reduce or eliminate the beta dependence of an emitter follower current amp? I'm looking for about 250mA. 24VDC source voltage. ~95 ohm load. Purpose: I'm testing a coil with a variable current source controllable from a computer controlled 0-10VDC output. I'm doodling an...
by rosborne
Mon Aug 16, 2004 5:06 am
Forum: General Discussion
Topic: OPNIONS WANTED sounds too good to be true
Replies: 80
Views: 15955

Re: OPNIONS WANTED sounds too good to be true

perfectbite,<p>That's how modern engineering works. If an engineer comes up with the idea for something neat, the corporation that employs the engineer owns it . . . even if it has nothing to do with the engineers job. Even if the engineer is burning the midnight oil at her or his residence. Anyway,...
by rosborne
Thu Aug 12, 2004 4:03 am
Forum: General Discussion
Topic: Build to order (or swap)
Replies: 24
Views: 4097

Re: Build to order (or swap)

My wife and I used to belong to a babysitting exchange. The idea was to watch someone from the pool of users kids and score hours of labor which could then be exchanged with anyone else in the pool to get babysitting. I thought it was a great idea, but it didn't quite work because not everyone in th...
by rosborne
Mon Jul 26, 2004 9:55 am
Forum: General Discussion
Topic: OPNIONS WANTED sounds too good to be true
Replies: 80
Views: 15955

Re: OPNIONS WANTED sounds too good to be true

'churlish' now that's a word I don't see every day. My guess is that you read books, sir.<p>I tip my hat to you, even though it exposes my baldness :) <p>-Rick (feeling a little goofy today)<p>Only the nose knows. Only the does doze. Only the beaus bows. Only the toes tows. Only the hose hoes. Only ...
by rosborne
Thu Jul 22, 2004 5:02 am
Forum: General Discussion
Topic: Board usage
Replies: 4
Views: 853

Board usage

I saw a thread that has been troubling me and leads me ask some questions.<p>Where in the rules of this forum does it state that we may not ask commercially related questions? <p>I have on more than one occasion asked for guidance in this forum because I wanted to know something for my day job. The ...
by rosborne
Wed Jul 14, 2004 7:13 am
Forum: General Discussion
Topic: Remote Control Lawnmower
Replies: 11
Views: 1801

Re: Remote Control Lawnmower

Yes, bring it over to my house for a demo. ;)
-Rick
by rosborne
Tue Apr 13, 2004 11:29 am
Forum: General Discussion
Topic: Instrumentational Amplifier
Replies: 3
Views: 679

Re: Instrumentational Amplifier

The impedance of an op-amp closed loop is very large. Even open loop I think you will see impedances in the range 20K and IIRC the impedance closed loop is about the open loop gain (A) times the open loop impedance or 20k * 70k or thereabouts. These values are determined by the designers of the IC a...
by rosborne
Mon Dec 15, 2003 6:11 am
Forum: General Discussion
Topic: RMS of a triangle wave???
Replies: 16
Views: 2952

Re: RMS of a triangle wave???

AI, <p>You are right about the slope thing, that was a half baked idea that occured to me while I was defining the shape of the triangle. I forgot that the slope of the triangle wave has an impact on the period of the waveform. I came up with an idea that you rightly called me on because it was BS. ...
by rosborne
Sat Dec 13, 2003 3:20 pm
Forum: General Discussion
Topic: RMS of a triangle wave???
Replies: 16
Views: 2952

Re: RMS of a triangle wave???

Whoops, and<p>Mr AI, I have no idea what you could be sorry about. I thought that what I wrote complemented and expanded on what you wrote. I even came up with the exact same answer Vp/sqrt(3) = Vp/1.732 although I see that I forgot the Vp.<p>As far as what happens when there is a DC component I thi...
by rosborne
Sat Dec 13, 2003 3:06 pm
Forum: General Discussion
Topic: RMS of a triangle wave???
Replies: 16
Views: 2952

Re: RMS of a triangle wave???

Mr. AI said,
>Sorry rosborne, but Vp/1.732 is correct for
>triangles and sawtooth waves.
Perhaps i misunderstood the point you were
trying to make?
by rosborne
Sat Dec 13, 2003 2:37 pm
Forum: General Discussion
Topic: MOSFET, HEXFET,IGBT,ChargePump etc...
Replies: 10
Views: 1996

Re: MOSFET, HEXFET,IGBT,ChargePump etc...

I think IGBT (Insulated Gate Bipolar Junction Transistor) is like a Darlington connectected transistor pair except the first transistor is a FET of some flavor and the second transistor is usually a big BJT. I saw one at my last contracting gig that probably weighed about 10 lbs. The heatsink was si...
by rosborne
Tue Dec 09, 2003 10:19 am
Forum: General Discussion
Topic: RMS of a triangle wave???
Replies: 16
Views: 2952

Re: RMS of a triangle wave???

Mr. AI is correct, although I can not help myself but add the following. A triangle wave is often refered to as a sawtooth wave and consists of two triangles. And to change his notation from x and y to t and y. The integration takes place over the period (Tau) over the two parts of the triagle defin...
by rosborne
Mon Dec 08, 2003 9:13 am
Forum: General Discussion
Topic: Amps to watts
Replies: 13
Views: 2260

Re: Amps to watts

P(power) = V(voltage) * I(current) * cos (theta) E = V and is voltage according to an old tradition (I learned it in the Navy almost 20 years ago). theta is the angle between the voltage and current and is known as the phase angle. In DC the phase angle is zero, also if the load is purely resistive ...
by rosborne
Mon Nov 10, 2003 12:54 pm
Forum: General Discussion
Topic: Where are the LM566?
Replies: 4
Views: 1117

Re: Where are the LM566?

Does your school stockroom hold it? If not you might want start researching a VCO that has similar specs.<p>Rick
by rosborne
Mon Oct 27, 2003 12:45 pm
Forum: General Discussion
Topic: Cascading linear regulators
Replies: 8
Views: 1746

Re: Cascading linear regulators

The trouble is that I'd like at least 2 amps from the 1.2 V regulator.
-Rick