Group project, to create a file of equations, rules of thumb and handy approximations

Five minutes = one microcareer

Regards PN2222A

That is: 1 uH parallel with 1 pF resonates at 2 meters (150 MHz), roughly

Frequency is inversely proportional to the square root of LC, so if you multiply *both* L and C by the same number, you get to divide the frequency by that number.

Thus 100 uH parallel with 100 pF resonates at 1.5 MHz.

And so on!

If you have a table of s-parameters, scan down the S11 list until you hit about 37 degrees lag. The recipriocal of that frequency is the input capacitance in pF. You can really surprise people with that one.

John

one million telephones or one trillion microphones = 1 megaphone

Don't test how hot your soldering iron is with your thumb. ;-)

previous

is

benefit

Well, which finger should I use then?

One on either hand of the guy at the next bench, of course.

Pico De Gallo - a very small parrot.

The time between hitting the "send" button and realizing you'd made some idiotic blunder: 1 ohnosecond. ;-)

Speaking of bodies, I've heard that "normal" is for your height to be 6 X the length of your foot, and from fingertip to fingertip with outstretched arms is the same as your height. I think the height of just your head is usually the length of your foot, also, but I'd have to check that one.

You can reach exactly around your wrist with your thumb and forefinger.

You can reach exactly around your neck with the thumbs and middle fingers of both hands.

There's a bunch of other cute relationships like that, but none of them uses clever prefixes, other than to say I'm a hexafoot long. ;-)

Cheers! Rich

Of course not. Use the upper lip (not too close though ;-). It's surprising how sensitive the upper lip is to IR.

Ok, here is a more practical one; Estimating the size of a power inductors made with the standard toroidial MPP type cores in the range of 1uH to 1000uH. D= (L^.334 * I^.667)/10 D= diameter in inches, H= height in inches L =uH I=amps H=D/2 This sized is for potted units. Reduce size by 10% for open units. Stacking core will reduce D and increase H by an unknown amount. If you design your own MPP power choke and it doesn't come close to these dimensions then you have done something wrong or do not have an optimum design. Enjoy, Harry

Pico Boulevard = 1E-12 boulevard.

milliskirt?

martin

Here's some to start with:

Instead of 22/7 for PI use 666/212. Its closer and it spooks some people.

When coding a CPLD, the ratio between all gates used and when the design won't fit any more is about 60%

RS-232 will work though about 10E6/BAUD feet of cable with normal drivers. Its only about 1E6/BAUD for labtops.

The SMT ceramic capacitors in a DC to DC converter running at 2.5KHz will be louder than the piezo beeper.

I'll remember that one.

I did ~ 98% once on an analog array, but it was blood, sweat and tears getting there... unappreciated by the client.

I'll have to check my lab notes. I once ran some gawd-awful rate over shielded-twisted-pair by using pre-charge... tested with a spool of wire bigger than my desk.

Squeaks ?:-)

...Jim Thompson

For the first-timer:

1 ballbreaker = the amount of effort needed to redesign it.

Handy approximations:-)

ware ~= wear

where: the units are in Harrys

Likewise:

Shack ~= Shaq

In article , Jim Thompson wrote: [...]

Analog circuits tend to have less interconnections so they don't exhaust the interconnect resources quite so fast.

I was refering to using standard drivers. Using a driver with "trebble boost", you can do a lot better than this.

Customer: "I can't turn the audio down"

"Trebble" = "treble" ?:-)

What I did was add an impulse to each edge. I suppose that's equivalent to treble boost.

...Jim Thompson