Ale
Guest
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 Posted:
Tue Mar 01, 2005 7:40 pm Post subject:
Urgent: reduce TTL 20MHz voltages... |
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Hi.... I have a stupid question... and I have to solve it as soon as
possible... but this, probably, does not matter :)
Well, the problem is trivial, but I did not solve it.
I have a 20MHz TTL. I have a PA that will drive a LED. All work when I use a
variable signal generator, but when I use the TTL source, I know I have to
attenuate the TTL signal because the PA accept a maximum of 200mVpp. I
assumed to solve the problem in this manner:
IN -----\/\/\/\------ GND
^
| OUT
Well.... I put also in series of the IN and the resistor a 75Ohm resostor to
avoid shortcut.
OK.... so many years I do not make any electronics that I am not following
the point.... As out I have a distorted signal. Fair enough, but I could
leave with a smoothing, what I get is a multi-step "square-wave".
Furthermore I do not have a real control of the levels, but I just get all
or none effect with a 1K3 and 100K variable resistors....
How can I solve this trivial problem.... in a simple a fast way?... thanks
:)
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Ale
Guest
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| Posted:
Tue Mar 01, 2005 8:21 pm Post subject:
Re: Urgent: reduce TTL 20MHz voltages... |
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Please almost ignore my previous message!!!!!
I only had a problem with the impedence of the oscilloscope... now it is
ok.... (I hope also with the PA :))
"Ale" <_cutbetweenunderscores_theopps75@ya_ho_hoo.it> wrote in message
news:d01rcc$1coo$1@gwdu112.gwdg.de...
| Quote: | Hi.... I have a stupid question... and I have to solve it as soon as
possible... but this, probably, does not matter :)
Well, the problem is trivial, but I did not solve it.
I have a 20MHz TTL. I have a PA that will drive a LED. All work when I use
a variable signal generator, but when I use the TTL source, I know I have
to attenuate the TTL signal because the PA accept a maximum of 200mVpp. I
assumed to solve the problem in this manner:
IN -----\/\/\/\------ GND
^
| OUT
Well.... I put also in series of the IN and the resistor a 75Ohm resostor
to avoid shortcut.
OK.... so many years I do not make any electronics that I am not following
the point.... As out I have a distorted signal. Fair enough, but I could
leave with a smoothing, what I get is a multi-step "square-wave".
Furthermore I do not have a real control of the levels, but I just get all
or none effect with a 1K3 and 100K variable resistors....
How can I solve this trivial problem.... in a simple a fast way?... thanks
:)
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