[time-nuts] Opening an Isotemp OCXO

Peter Reilley preilley_454 at comcast.net
Fri Oct 28 15:28:55 EDT 2016


That seems the most reasonable thing to do.

Pete


On 10/28/2016 3:20 PM, Tom Miller wrote:
> 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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