To: rsgb_lf_group@blacksheep.org
References: <1UQRRBrZ33.5N62o0UWd72@optiplex980-pc>
 <1b2b034a-404d-8b95-220c-5568950a1918@n1bug.com>
 <1523452469895.92892@kuleuven.be>
 <8c1acac6-e271-6398-2768-481298344387@n1bug.com>
 <1523457751831.88599@kuleuven.be>
 <b7a29220-1f9e-ac8e-87d5-53d0c75708ab@n1bug.com>
 <612685899.20180411225537@gmail.com>
 <BFE1E3A433664900AE95DE6D9EE733BC@StevePC>
 <968686644.20180411232838@gmail.com>
 <7950E881690348FB8A48C42DD2735F8D@StevePC>
 <1UQRSH98Tx.2IrTZ1ue7L6@optiplex980-pc>
From: N1BUG <paul@n1bug.com>
Openpgp: preference=signencrypt
Autocrypt: addr=paul@n1bug.com; prefer-encrypt=mutual; keydata=
 xsFNBFqj1+0BEACggWlaH8oG/AiXSUG3CeQwZ1NrVEP4U7YsA9N9XEffjCDEsnTjHF2BJSgS
 2AicyomkmTGvghEHxrNFfFw07jwgJl97ae/VtNxpERPSE98mb4sPOMpJbwddioMazMDXwhKA
 wpg5fse+Ru8OrIT04KK919xL/pZuAP6pY6d2kVoizjJOfS71pHpiU6N6q3d9cl+w7d2LKhAE
 a3A1ZgDquPvn0WQlrN8K5D66xVrwTRhf1b5H4Ozl8/mMJzCeLG1ZIsDB3Pu2flwE81P8dCJA
 y1azwgY8pTEshVk4em/se9uRiZaDJr/qUSCf6hrV7AGa8g1jpAQDmdGpDNYMqyDqXen4jNi1
 8kNFVu1BMl2vjaI8skw/YPxIxlk/0ROHYhN6SuoDq1mt4AW4FryNa7k3A8dM8Bt7udBoTv0i
 uw4j9R/bmh2vl/QaHRUhDco0xn2z6geWvXkKqha++vzXDrEKUuqgB85SDZPs5W/phs9p0pz1
 xA61d1gn8FQJtpou5dQuAucqMo8eKQY5LUcbC+MH5pebH+M2wIuDCBmFPJHQDSPNepeaxJ4o
 G/HU1hrpzlgLiTTSKR8DcwtMQwYywnCTlm8MgL4jXuPzoGyKDMYyKIjC51G+3AAOJ6oXJAGR
 g0ehhCPtmnCGBaRlUIoUSpbgc4B+onqFKZmDiVm9CRNJhKIWrQARAQABzRZOMUJVRyA8cGF1
 bEBuMWJ1Zy5jb20+wsF9BBMBCAAnBQJao9ftAhsjBQkJZgGABQsJCAcCBhUICQoLAgQWAgMB
 Ah4BAheAAAoJECRS/J8srRGjPBsQAIh+Haz9gqrQJ0OlMI5xmQ0A5nsVWcatWF/Ea4mucNjL
 4n4jmW+Z4Ukn3OVss55chWwrOVMRNWU2d2zRc92ZF7yJhLCoJFV870bZfxNYwdJ3GEBLIu6/
 anmQYX0oXFx8UBsx5K6egNqbeflPA7zrLiQkWrz6JApECdiA1rHDjyJdS7PDxBCG9cKgr/5b
 r4Rn/JlUl9pRPnxlSwHXsV+J6JtFYtWI69MWIVD7Y7OY1wO9+684uOnzeDANzeIwpBDcSm6p
 0D5u0b1hfPl2TD0ozVs6P0NvxkMbimXUhRR1QD0FvydyxmZTLAo+XZDGR8GqWYrYrauoRZ1h
 3m23+bNT2T4AuoFnWekpsZu+sxIf0LKPtEZCa51O65jZ810ROpXg9Lx71gEoQD+kbjO69+kq
 9r7wjytDq/jyhpOGrGYV6kgcQrISY86t9YvkA9Of2HDzZLih3GwecW6fkeV1AO5w4RteE9nL
 zIs2siGw2YqavF6LpTH71Db7cUYyZWn5hkKpwfpLNnPEuqgZACovpH1WUHx+KMqqIL4rMVCH
 GcSLqnH2KF4cEDb6OeTbwuLfpGlN+I3j24eQnB2uz5rDa7/IBjsClLl8S/wdDTP8IikBGixX
 06v3k06tk/OF4UsfJ0cY/ASGP5+kjT4ASMZAIikwVMpKi5A5be77vecKNYlJQ2a6zsFNBFqj
 1+0BEACaujZXo3F17v7QTnub4DjjYvm+nr8J0uU5pPc1UMEz9eWjmtmITm15fx1hPKNtVW+I
 VlT+DG+ShNnYmO2M4CFBoc7PwkAOc70aDxfHz20kotvj1HhXG7oBiqPkN3TK4C7qWV1HUEPA
 V960qPdhsoCqmtkvNwj39w1T0ZR5qwwaqDogs9UwBib7zseQ3OXHG32xYYCMcxM35hgXGkkz
 R7wFL4ZnAPOeFb8LnWtZcrGpwXdsYkXuCxm+A+u9KlFY+w3ZCzZt1F9Ie+/PSZnFIUtbXt2i
 mfc+VkRwOLz5BDAeWuDL09TN81+gbrR3kXlymDcCbuduO/yHOQK085qzE3LuImdy+JNb7oDf
 1C/hvpRvtB02vVy33rzIXT8644SJzFY/mw/W39/BgHKCoL1FrBbfgf0UoIFw5M752i7jQwmv
 j5yFfnVAXIPpCuusMwWMGVpZcGV7QxJxh0HBEhYgOo9v3zKwzNIPm9V/LA67u/rj4a/MlCE0
 mpd6IHaePE1vXDaboPZHZdhAziru5/Jd7KQI0k+HmM/HRANPRNDZ4UeBpgj9PzS6hDN5GHlZ
 fRUbI8JAg9wSaQtEn0bjyaR7lw0yngZTvvjT1Qqt5zGwm1IAall2STes5xK0aS7p+UJJMVbf
 ydZ5VOnocvUkwYxbiqoyuVtGxi4tpWW9CRstYXMkAwARAQABwsFlBBgBCAAPBQJao9ftAhsM
 BQkJZgGAAAoJECRS/J8srRGjTDMP/18q7uhac/naxoFsOqhgXIlvaPgu6GX7s/QOh+bcSV1F
 y50lxo51P/C95H2TVME/CtCjk2xWQcNjWtXloMEsZpl7T3qWgJHvyZYkDtgh3M6UNY+zb08U
 K9E2+rR0AZ6zdMKio7Z1xA9BtbUpSZpvy2NgjoYVqo35NllUWMZJq0u+88PvE5WeCIqLipNI
 EZmUcG9UwolQbPkrRc42ReL+bFbuXGXDA5GbQ0RudXbugI8iUwaw3ftaKElIZtuHW0hw1VrU
 9tVHsxKyEoKgNNT1hr+dgRmvCHmA87Pi4R5cMV0ZkLVOYfPX1motedag7HmSNPi2PkYLts4z
 kyvPEJe2IvaPvjvK1ShRWWgje3uytrhfwyjUZcIuA76RWEfBbwT2Mbrn9O7LvrYtbTiTlsLo
 Zdk2uocuefBvPd2oI7mTn5eLy/VDy2JVnlb9vpZZhriXI4KtCcP6mYyuPxlxqj/30Kn1fU5b
 C4EpnKy6hW1CHM42DbwzT+ChjBpFbX9bfwT4qn6d42+T4mN5wkmfnBRHfcn8Wf1ezRSK3Ome
 Esa3ZDssj23CZHe11uec6Ln14qoB7JyRT9qM3Q99tzvAlmWFM3GrSsG94g4JponQjQWHmr8B
 eMYezwJHzSI7zWElJpzs/OuohstTYfYTy16FygUOEinc1K4ywjEklgRpXRtjKvqc
Message-ID: <fac63396-7bbf-f5f5-cdda-9256f10ab8ec@n1bug.com>
Date: Thu, 12 Apr 2018 10:51:38 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.7.0
MIME-Version: 1.0
In-Reply-To: <1UQRSH98Tx.2IrTZ1ue7L6@optiplex980-pc>
Content-Language: en-US
Subject: Re: LF: W1VD amp help - more waveforms
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Jay,

I agree everything points to a problem in the driver circuit.

This morning I set up the scope very carefully, took pictures of the
gate waveform with the 2000pf. I then removed the added cap on each
side to get back to 1000pf and took pictures of the gate waveform
again. Looking at before and after pictures side by side there is
*no* difference!

I've gone over the driver board several more times and cannot find
any construction errors. With the IR2110 in circuit, pin 10 measures
14.55k to ground, pin 12 14.66k to ground. With the IR2110 removed I
measure 14.93k and 14.81k respectively.

I tried to look at some other things but got hopelessly confused.
With the IR2110 removed from the socket... 74F74 output is a square
wave +4.2V/+0.2V... at the IR2110 input pins (chip still removed)
+2.2V/-2.2V square wave which decays linearly to +1.8/-1.8V on each
cycle. I guess it being centered around zero is because I am
essentially AC coupled through the 1000pf cap? With one scope probe
on the 74F74 pin 2 and the other on the IR2110 pin 12 I see no delay
or timing difference whatsoever, just the sloped top and bottom of
the square wave. I cannot take pictures because I don't have enough
hands.

With the IR2110 in the socket... 74F74 output +4V/+0.1V square wave.
IR2110 input +3.7V (decaying to +2.7V), -0.6V (decaying to -0.4V)
with vertical rise and fall. I still see no delay in rise/fall times
between 74F74 pin 2 and and IR2110 pin 12. Should I be seeing a
delay or at least some softening of the rise/fall?

Still not being satisfied that I was confused enough for one day I
looked at both IR2110 inputs. The rise and fall are vertical on both
with no delay evident in this test either. When one is rising the
other is falling making a single vertical line on the scope. This
can't be right, can it? The whole idea is to create a delay between
phase transitions at the IR2110 input, isn't it?

The only possibilities I can think of are that these capacitors
don't work in this circuit or I have a bad chip. But even the latter
doesn't seem to explain this.

Totally lost...
Paul


On 04/11/2018 08:50 PM, jrusgrove@comcast.net wrote:
> Paul
>  
> I just tried my earlier suggestion of doubling the value of the
> 'timing' capacitors to 2000 pF on the amplifier. As expected, the
> dead zone between the phases about doubled ... and is
> now significantly wider than necessary. I'm having a hard time
> understanding how you have no dead zone with 1000 pF caps ... and
> adding an additional 1000 pF makes no difference to the
> waveform!  Believe that if you solve the missing dead zone
> issue you'll solve the excessive ringing. Something is amiss in your
> driver circuit.
>  
> Jay W1VD