W
Watson A.Name - "Watt Sun
Guest
http://members.shaw.ca.novotill/FlashlightTimers/index.htm
I used my Spice Simulator[1] to experiment with the first schematic on
this web page. The changes I made were:
9014C -> 2N3904
9015B -> 2N3906
8050D -> BC639
470 ohm -> 1k
Light Bulb -> red LED with 120 ohm res in series
I'd say the transistors are just about equivalent. The one
disadvantage of this circuit is that one can't extend the time by
pressing the push button switch. The light has to dim before it will
retrigger for another time period.
Another point that I like about the second schematic but this one
doesn't have is that the light fades slowly thus allowing the user to
reset it. If the light dims to darkness quickly, the user can't see
the unit to press the button!
I think I'd change the circuit to accommodate 3 or more LEDs by giving
each LED its own transistor and base resistor. That would allow using
cheaper, lower current transistors like the 9014C or BC337 or 2N4401.
But then, perhaps a single 8050 is cheaper than three 9014s.
http://www.futurlec.com/Transistors/C9014pr.shtml says 9014s are $4.00
a hundred.
[1] Spice Simulator: I simulate Spice by building the Real Thing. ;-)
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
I used my Spice Simulator[1] to experiment with the first schematic on
this web page. The changes I made were:
9014C -> 2N3904
9015B -> 2N3906
8050D -> BC639
470 ohm -> 1k
Light Bulb -> red LED with 120 ohm res in series
I'd say the transistors are just about equivalent. The one
disadvantage of this circuit is that one can't extend the time by
pressing the push button switch. The light has to dim before it will
retrigger for another time period.
Another point that I like about the second schematic but this one
doesn't have is that the light fades slowly thus allowing the user to
reset it. If the light dims to darkness quickly, the user can't see
the unit to press the button!
I think I'd change the circuit to accommodate 3 or more LEDs by giving
each LED its own transistor and base resistor. That would allow using
cheaper, lower current transistors like the 9014C or BC337 or 2N4401.
But then, perhaps a single 8050 is cheaper than three 9014s.
http://www.futurlec.com/Transistors/C9014pr.shtml says 9014s are $4.00
a hundred.
[1] Spice Simulator: I simulate Spice by building the Real Thing. ;-)
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@