Subject:
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re: ztx614
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 17 Mar 1997 15:41:49 GMT
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Original-From:
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Jeffrey Strauss Morehead <morehead@ece/ihatespam/.utexas.edu>
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Viewed:
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2400 times
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If I have interpreted the schematics correctly almost any npn can be used
for the ztx614. The 614 simply provides ground for the IR transmitter with
a collector current of about 3ma. The base current is set by the 10k R to
about (5/10k) 0.5ma. If I have calculated f=1/2*pi*RC for the TOC5 enabled
oscillator, then the frequency max of the IR output is in the kilohertz
range.
This all means that almost any medium power npn can be used! I am
building my own board and could not find the part either. I am going to
finish my board tonight and I am substituting a 2N3904 for the ztx614.
I can't figure out why a high frequency darlington was used here. If I am
wrong someone please let me know, otherwise I will find out tonight!
hopefully correct,
jm
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Message has 1 Reply:
 | | re: ztx614
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| (...) I think it must better be a darlinghton and it must support enough current: if you want to get 0.1A or more pulsed current in the IR led, the transistor must have a rather high current gain, more than that of an ordinary npn trans (by the way (...) (28 years ago, 19-Mar-97, to lugnet.robotics.handyboard)
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