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From: lektric.dan on 20 May 2010 19:34
I want to thank everyone that helped my with the level and flow sensor
problems. I was trying to use Radio Shack phototransistor/IRLED pairs
- part # 276-0142. I couldn't get any of the circuits to... work
reliably. It was very frustrating, trying to diagnose what I had done
wrong. Then yesterday, I stuck one of the phototransistors on a curve
tracer. It was worthless. OK, maybe I fried it, hooked it up
backwards or something. Tried one I had opened but not hooked up in a
circuit - again worthless. I had a technician open a NEW package and
test the pt. Worthless. Maybe these would make resistors, and not
good ones, but they do NOT function as transistors or
phototransistors. I bought some Vishay units from Mouser and tried
them out today. The circuits now work the way they should. *sigh*
Rat Shack is close and convenient, but full of worthless
semiconductors. I've got to do a little more planing to order parts
instead of just running down the street, but buying reliable parts
will make life easier. Again, thanks for your help, and thanks for
listening to my rant
From: George Herold on 20 May 2010 20:53
On May 20, 7:34 pm, "lektric....(a)gmail.com" <lektric....(a)gmail.com>
wrote:
> I want to thank everyone that helped my with the level and flow sensor
> problems.  I was trying to use Radio Shack phototransistor/IRLED pairs
> - part # 276-0142.  I couldn't get any of the circuits to... work
> reliably.  It was very frustrating, trying to diagnose what I had done
> wrong.  Then yesterday, I stuck one of the phototransistors on a curve
> tracer.  It was worthless.  OK, maybe I fried it, hooked it up
> backwards or something.  Tried one I had opened but not hooked up in a
> circuit - again worthless.  I had a technician open a NEW package and
> test the pt.  Worthless.  Maybe these would make resistors, and not
> good ones, but they do NOT function as transistors or
> phototransistors.  I bought some Vishay units from Mouser and tried
> them out today.  The circuits now work the way they should.  *sigh*
> Rat Shack is close and convenient, but full of worthless
> semiconductors.  I've got to do a little more planing to order parts
> instead of just running down the street, but buying reliable parts
> will make life easier.  Again, thanks for your help, and thanks for
> listening to my rant

Sigh, that is too bad. Getting things to work is hard enough without
bad parts. I've learned to stay away from Jameco too.

George H.
From: Michael A. Terrell on 20 May 2010 22:32

"lektric.dan(a)gmail.com" wrote:
>
> I want to thank everyone that helped my with the level and flow sensor
> problems. I was trying to use Radio Shack phototransistor/IRLED pairs
> - part # 276-0142. I couldn't get any of the circuits to... work
> reliably. It was very frustrating, trying to diagnose what I had done
> wrong. Then yesterday, I stuck one of the phototransistors on a curve
> tracer. It was worthless. OK, maybe I fried it, hooked it up
> backwards or something. Tried one I had opened but not hooked up in a
> circuit - again worthless. I had a technician open a NEW package and
> test the pt. Worthless.


Did you cover the phototransistor with something to block all light?
If not, it was biased into saturation by ambient light.


> Maybe these would make resistors, and not
> good ones, but they do NOT function as transistors or
> phototransistors. I bought some Vishay units from Mouser and tried
> them out today. The circuits now work the way they should. *sigh*
> Rat Shack is close and convenient, but full of worthless
> semiconductors. I've got to do a little more planing to order parts
> instead of just running down the street, but buying reliable parts
> will make life easier. Again, thanks for your help, and thanks for
> listening to my rant


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
From: lektric.dan on 20 May 2010 23:18
On May 20, 9:32 pm, "Michael A. Terrell" <mike.terr...(a)earthlink.net>
wrote:

>    Did you cover the phototransistor with something to block all light?
> If not, it was biased into saturation by ambient light.
>
As a functional teas, I drilled a hole thru a 1/2" MNPT nipple. Stuck
an IRLED in one hole, the pt in the other. Worked intermittantly,
with the two devices in very close proximity and facing each other.
This is how the circuit will be used in "real life". Vishay pt works,
no problem. I'm using Vishay BPV11.
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