saturated switch: first or second law?

[duck_arse]

fiddling with the mc34063 again, it is suggested (app note) my life will improve by 12% by adding an external pnp saturated switch. working, as ever, within the constraints of the first law of MBAism, I have no such designated parts. applying Keen's second law, which am I reaching for, a BC327-8, a BC557-9, a 2N2907 or a 2N3906? what is the wrinkle in the datasheet of a saturated switch as opposed to a "switching" type or a "gp" type. construction or application?

and, as I am only inverting to -9V for a silliface, is there any point in the 12% better life, considering the extra calculations and the somewhat bizarre figures they have produced for base currents/resistors? and further, is the V_sat figure in the calcs the external transistor's V_CEsat or the less likely V_BEsat figures?


(does anyone know if there was ever a spreadsheet or java thing to do the page of calcs for these chips?)

[R.G.]

We don't need no stinking spreadsheet.   

For saturated switching, the big questions are how much voltage and current, and how fast. If you're switching 9V power, ignore the voltage, you're fine. Next current - what is the peak current in the transistor switch?

Once you know that, you go look at Vcesat, which is the saturated voltage between collector and emitter at a given current. The numeric tables tell you the min and max limits at one or a few currents, but go look at the graphs of Vcesat versus current for the typical. Notice that the "typical" charts give you a curve at Hfe=10 (probably). This is the manufacturer's gentle way of saying "whack the base with 1/10 as much base current as you're switching on the collector if you want the voltage to go this low."

2N2907 and 2N3906 are both fine with saturated switching, the 3906 is higher gain - which doesn't matter much in this case.

I haven't looked at your IC sheets or the equations; this is all very general advice.

[duck_arse]

thanks for the reply.

We don't need no stinking spreadsheet.   

I only know this quote as "we don't need no steenkink license", from an episode of rager ramjet, something about the treasure of the seirra madres. I'm guessing that was a paraphrase, but of what?

and as for the other. my calculations said 22mA peak current, but working through to the bitter end I came up wanting 630uA for base current, and another 37mA for the Rbe calc. this is when I decided to go without. wound a toroid (spot on value, no messing, first go), threw it on the bb, works fine. 10mA input for -9V @ 2.6mA across a load, less than bugger all ripple. so I'll have a listen tomorrow.

12% of SFA works out to be not much. still, it must be nice to have more of something.

[Jdansti]

From the original...

http://www.youtube.com/watch?v=VqomZQMZQCQ  

[duck_arse]

mmm, but utube is usually a no-go this end, and especilly now I gots no audio .... any hints?

[Jdansti]

From Wikipedia: http://en.wikipedia.org/wiki/Stinking_badges

"Badges? We don't need no stinkin' badges!" is a well-known and widely (mis)quoted line from cinematic history.[1] In 2005, it was chosen as #36 on the American Film Institute list, AFI's 100 Years...100 Movie Quotes.[2] It comes from a line of dialogue from a 1927 novel, The Treasure of the Sierra Madre, and first appeared in film 21 years later in a movie of the same name. The line was parodied in a 1967 episode of the Monkees TV show called "It's a Nice Place to Visit" and in the Mel Brooks film Blazing Saddles in 1974 and was cited in many movies after that.

The original version of the line appeared in B. Traven's 1927 novel The Treasure of the Sierra Madre:
"All right," Curtin shouted back. "If you are the police, where are your badges? Let's see them."
"Badges, to god-damned hell with badges! We have no badges. In fact, we don't need badges. I don't have to show you any stinking badges, you god-damned cabrón and chinga tu madre!"

The line was popularized by the 1948 film adaptation of the novel.[3] In one scene, a Mexican bandit leader named "Gold Hat"[4] (portrayed by Alfonso Bedoya) tries to convince Fred C. Dobbs (Humphrey Bogart)[2] that he and his company are Federales:
Dobbs: "If you're the police where are your badges?"
Gold Hat: "Badges? We ain't got no badges. We don't need no badges! I don't have to show you any stinkin' badges!"

In popular culture:

In the TV show The Monkees episode 33 "A Nice Place To Visit" (1967), Micky Dolenz misquoted the line as "Badges? We don't need no stinking badges".

In Mel Brooks' 1974 Western Blazing Saddles, the line was delivered as "Badges? We don't need no stinking badges."
In the 1980 film "The Ninth Configuration", when the asylum patients were quoting lines from movies, one quotes "Badges, we don't need no stinking badges".

In the 1983 TV series Wizards and Warriors, the character Marko (played by Walter Olkewicz) delivers a spoof of the line as "Badgers? We don't need no stinkin' badgers."

In the 1986 Stephen King novel It, character Richie Tozier repeatedly says in a poor imitation of a Mexican accent, "Batches? We don't need no steeking batches."

In the 1980s TV series "Sledge Hammer" episode "Sledge in Toyland"(SE02EP11) Sledge and his partnner arrive at the office of the murdered toy tycoon and the security guard sticks a visitor's badge on his chest. Sledge throws it on the counter saying: "Heeeey, I don't need no sticking badges."

Early 1980s rock band The Minutemen's song Badges included the line "We don't need no badges, we don't need no stinkin' badges"

The 1987 Luis Valdez play I Don't Have to Show You No Stinkin' Badges draws its title from this quote, and makes a specific reference to Sierra Madre.

In the 1989 "Weird Al" Yankovic film UHF, when Raul (Trinidad Silva) is asked to take a consignment of badgers, he says "Badgers? We don't need no stinking badgers!"

Julian Cope's semi-eponymous song Julian H Cope from his 1992 album Jehovahkill featured the line "Badges? Badges? We don't need no stinkin' badges! So sissified, civilised, I want to be a savage".

In the 2001 film Bubble Boy (film), when Jimmy offers Danny Trejo's character Slim patches for his motorcycle's flat tire he responds, "Patches? I could use some stinking patches."

In the 2002 Friends Season 8 episode "The One with the Baby Shower", the quote is mentioned as one of Joey's training questions for the show Bamboozled.

In the 2005 book Eldest, the second novel in Christopher Paolini's The Inheritance Cycle series, a cobbler named Loring eschews the use of barges as a means of human transportation, saying "Barges? We don't want no stinking barges."[5]

In the 2008 film "Zombie Strippers", when Paco (Joey Medina) is told to obtain some wild animals to dispose of the bodies, he says "Badgers? Badgers? We don't need no stinking badgers".

[duck_arse]

I'm quite proud, my own thread completely derailled after only the third post, and it wasn't even my fault.

I can't believe roger ramjet doesn't figure high enough in american pop-culture to make that list. it was probably even earlier than the monkees ref. I have a 12" transcription (not for sale) with six-episodes I'll need to look at, the only reason I got the film title.

mmm- buzz -- mmm - klik!

[Jdansti]

>I'm quite proud, my own thread completely derailled after only the third post, and it wasn't even my fault... I'm guessing that was a paraphrase, but of what?  mmm, but utube is usually a no-go this end, and especilly now I gots no audio .... any hints?

Just trying to help... 

We don't need no stinking relevant posts! 

[duck_arse]

I've been resisting that temptation, jd.

so far. I'll bide my time, I think.

[duck_arse]

just for completeness ......

> unbuffered voltage divider for Vref going to interact with the Salen-Key filters?

Put a Big Frikkin Cap on Vref, we don't need no stinkin buffers.