1 Mar
2017
1 Mar
'17
9:56 a.m.
I'm not sure how something as simple as a cassette interface could be causing so much
issues.
Can you post a schematic of what you have now and what the signal amplitude is?
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of allison via cctalk
<cctalk at classiccmp.org>
Sent: Wednesday, March 1, 2017 3:10:50 AM
To: cctalk at classiccmp.org
Subject: Re: Cassette Interface Assistance
On 03/01/2017 01:40 AM, Jim Brain via cctalk wrote:
Single transistor audio amp before it.
Allison
On 2/28/2017 2:34 PM, Brent Hilpert wrote:
snippage
Obviously, given the LM339 issues, this is unworkable
in the end, but
it did get me to realizing some outputs on the LM339, so thanks to
both of you.
I can plainly see the oscillation on the comparator transitions, so it
is obvious I need a better comparator. I'll have to source a few
different comparator options from Digikey to fill my parts box.
Suggestions are welcome.
OR a bit of positive feedback.
Using the
internal AVR comparator sounds like a better final solution
(fewer components), but in devising an
input circuit for the AVR you may be running into the same issue of
loading a high-impedance source.
Though it plays into Tonly's notes about my
analog understanding (or
lack thereof), I was so disillusioned by the analog uncertainties that
I initial focused on the AVR comparator. By correctly biasing the
comparator, I was able to get much better results tonight, but the
lack of any ability to add hysteresis into the design hindered my
success. At transition, the signal simply bounces badly. I tried to
construct a low pass filter (22pF and 5K6), and some variations, but I
was not able to overcome. I then tried to deal with it in SW, but I
have not yet been successful. I'll try again, but lack of hysteresis
is a big issue.
Jim