[time-nuts] Opening an Isotemp OCXO

[Tom Miller]

It looks like that is the only device that could be damaged by 12 volts. Can 
you find a replacement and try running at 5 volts?


----- Original Message ----- 
From: "Peter Reilley" <preilley_454 at comcast.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, October 28, 2016 3:10 PM
Subject: Re: [time-nuts] Opening an Isotemp OCXO


> The reason that there was 12 volts on the unit was because I put it there. 
> I should
> have tried 5 volts first but the only datasheet that I could find said 12 
> volts.
> All the eBay units that look the same say 12 volts.
>
> Pete.
>
> On 10/28/2016 12:53 PM, paul swed wrote:
>> I confirmed the pin out matches a 74s30 also. An S30 is TTL. Great pix to
>> look at.
>> So 12 V on a 5 V chip is indeed a smoker. Find out why there was 12 V.
>> OK crazy talk I see a 1K resistor next to the VCC chip. Would anyone be
>> crazy enough to use a dropping resistor from 12 V to get 5?? Really bad
>> engineering and I don't actually believe they would. But if true a open
>> 74s30 would indeed show 12 V on pin 14.
>> Good luck.
>> Paul
>> WB8TSL
>>
>> On Fri, Oct 28, 2016 at 12:48 PM, jimlux <jimlux at earthlink.net> wrote:
>>
>>> On 10/28/16 9:13 AM, Scott Stobbe wrote:
>>>
>>>> The OCXO82-59 datasheet lists 12V supply, 5V clock out, could also be a
>>>> blown regulator in your ocxo, if it is indeed a 12v model.
>>>>
>>>> There you go..the design could use a 74S30 as a driver - it's fast,
>>> fairly good drive, but runs off 5V.  If the regulator is shorted, and 
>>> you
>>> put 12V on it, it will cook.
>>>
>>>
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