[time-nuts] TB DAC, was Re: Embarrassing stuff...

Azelio Boriani azelio.boriani at screen.it
Sun Jun 2 21:45:03 UTC 2013


OK, glad to hear you have your TB working again.

On Sun, Jun 2, 2013 at 11:32 AM, David Hooke <dhooke at gmail.com> wrote:
>
>
> Azelio,
>
> I was lucky, it was just the opamp, so the TB is happily driving the MV89
> again. Back to three cornered hat testing!
>
> The DAC is no more than PWM, so I'm guessing the reference (5V, not as I
> thought 4V) and DAC output are sampled by the CPU to get the PWM output
> close to what's required.
>
> One interesting thing: the Trimble oscillator is now dead (ignoring EFC). I
> had tried it after the MV89 failure, and it apparently didn't like more than
> +/-5V.
>
> Cheers.
>
>> and maybe that the DAC's output feeds an OPAMP first, if so then
>> replacing the OPAMP should fix the problem...
>>
>> On Thu, May 16, 2013 at 12:10 PM, David Hooke
>> <dhooke-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
>>>
>>>
>>> OK.
>>>
>>> This MV89 is mounted on a PCB with SMA connectors for the EFC, REF and
>>> 10MHz. I connected the EFC from the TB to the REF out of the oscillator,
>>> not
>>> for very long, and things haven't been quite right since then.
>>>
>>> I should not play in the workshop after drinking wine with dinner!
>>>
>>> It'll be interesting to see how Trimble designed the DAC. There doesn't
>>> seem
>>> to be much more than a 4V reference, a quad opamp and a bunch of RCs. I
>>> guess that as long as it's monotonic, accuracy is not overly important.
>>>
>>> Cheers.
>>>
>>> david
>>>
>>>> Fess up David. Tell the story.
>>>>
>>>> LOL,
>>>> Tom
>>>> ----- Original Message ----- From: "Burt I. Weiner"
>>>> <biwa-fOdFMYwuEsI-XMD5yJDbdMReXY1tMh2IBg at public.gmane.org>
>>>> To: <time-nuts-JSkTLETqlTM-XMD5yJDbdMReXY1tMh2IBg at public.gmane.org>
>>>> Sent: Wednesday, May 15, 2013 11:54 AM
>>>> Subject: [time-nuts] Embarrassing stuff...
>>>>
>>>>
>>>> David,
>>>>
>>>> I'm sure it's nothing compared to what I did many years ago to my
>>>> Singer FM-10C Synthesizer.  You tell us your story and I'll tell you
>>>> mine.  You're among friends.  Every time my life flashes before my
>>>> eyes it's mostly embarrassing stuff.
>>>>
>>>> Burt, K6OQK
>>>>
>>>>> From: David Hooke
>>>>> <dhooke-Re5JQEeQqe8AvxtiuMwx3w-XMD5yJDbdMReXY1tMh2IBg at public.gmane.org>
>>>>>
>>>>> Subject: Re: [time-nuts] three cornered comparison tools
>>>>>
>>>>> Hi All,
>>>>>
>>>>> I've managed to blow up the DAC output on my TBOLT; it now has about
>>>>> 0.5V 42kHz ripple on it. I think I know how I did this, but it's too
>>>>> embarrassing to share in public.
>>>>
>>>>
>>>> Burt I. Weiner Associates
>>>> Broadcast Technical Services
>>>> Glendale, California  U.S.A.
>>>> biwa-fOdFMYwuEsI-XMD5yJDbdMReXY1tMh2IBg at public.gmane.org
>>>> www.biwa.cc
>>>> K6OQK
>>>>
>>>> _______________________________________________
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>>>>
>>>
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>
>
>
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