[sdiy] understanding a common resistor symbol

[harrybissell at wowway.com]

You are not the first.

I was testing an incandescent strobe flasher that used an UJT and a triac, ran
directly off the AC line.

I was working on my parents BRAND NEW Formica top dining room table. They had
already sent the FIRST one back to the store because it had a scratch !!!

I plugged it in, nothing happened. No lights. So I checked the circuit
carefully, found some errors, retest.

The lamp LIT UP !!!  Hooray... at least SOME success... even if it doesn't
flash yet.

Then I hear this tiny hissing noise... getting louder like a jet plane warming
up for takeoff...

So I dive for the power cord, and pull the plug.  The hissing gets louser
still, and with a final WOOSH the whole circuit launches itself from the table
and five feet into the floor.

The table was covered with a fine crystalline residue... and when I cleaned
that away there was a nice SCRATCH in the table.  OH NO Mr. BILL !!!

I didn't say anything... when they noticed the scratch they called the store,
and accused them of bringing back the SAME table, only reversing which end
they carried in the house first....  The store swore they gace them a NEW
table... but they ended up bringing a new NEW table after that.

It really was my father's error... I asked him for a 50uF / 150V cap (can you
picture even that LOW of a rating on a 120VAC line ???) .... what he brought
was a 150uF / 50V cap... that explains the abrupt take-off and landing :^)

Lessons learned... CHECK capacitor ratings very carefully and DON'T WORK on
the good table !!!  (Dan, buy a card table and use that, or at least get a
sheet of masonite to cover the wife's table !!! :^).

I confessed to the crime close to forty years later.  My parents did not
belive me and still think the store tried to cheat them....  Oh well at least
I told the truth, somewhat belatedly...

Best of luck, dude !!!   :^)

H^) harry



On Thu, 16 Oct 2008 15:39:39 +0000, Dan Snazelle wrote
> thanks all
> 
> this is very helpful.
> 
> i think in the documentation it MIGHT be taken for granted you 
> understand the circuit from previous experience...i will re-read the 
> article in question to see if i can figure out what the value of the 
> B resistor might be.
> 
> sort of freaking out right now as i just melted a piece of the 
> finish on my wifes dining room table...i was using acetone to remove 
> the black on a just etched pcb board when i noticed my cotton balls 
> (still soaked) were soaking through the newspaper i had laid 
> down...oh no! only to find the inks from the paper and the acetone 
> eating into the surface of the table...when i tried to scrape it 
> off..it turned purple and melted the finish.
> 
> i turned the table around and put a placemat over it in hopes of discretion....
> 
> board came out good though..my first with two different pnp designs 
> on one board   ;)
> 
> --------------------------------------------
> check out various dan music at:
> 
> http://www.myspace.com/lossnyc
> 
> http://www.soundclick.com/lossnyc.htm
> 
> http://www.indie911.com/dan-snazelle
> (or for techno) http://www.myspace.com/snazelle
> 
> > Date: Thu, 16 Oct 2008 07:57:11 -0700
> > From: music.maker at gte.net
> > Subject: Re: [sdiy] understanding a common resistor symbol
> > To: synth-diy at dropmix.xs4all.nl
> >
> > The prime symbol comes from mathematics, it usually means that R and R'
are related
> > in some way. The relationship should be explained in documentation, there
is no
> > set definition.
> >
> > Bottom line is that they are just labels. The prime symbol may help you
understand
> > how the circuit works, but is no use for simply building a circuit from the
> > diagram, so as someone else suggested, they could be A and B or Horse and
Banana.
> >
> > -- ScottG
> > ______________________________________________________________
> > -- Scott Gravenhorst
> > -- GateManPoly - FPGA-based Polyphonic MIDI LA/FM Synthesizer
> > -- GateMan-III - FPGA-based Monophonic MIDI LA/FM Synthesizer
> > -- PolyDaWG/8 - FPGA-based 8 Voice Polyphonic MIDI Synthesizer
> > -- FatMan: home1.gte.net/res0658s/fatman/
> > -- NonFatMan: home1.gte.net/res0658s/electronics/
> > -- When the going gets tough, the tough use the command line.
> >
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Harry Bissell & Nora Abdullah 4eva