[time-nuts] Opening an Isotemp OCXO
artgodwin at gmail.com
Fri Oct 28 15:18:58 EDT 2016
The data sheet for the device only mentions 12V. Other data sheets (eg the
131) mention 5V and 12V, but don't indicate how to specify one or the
Gerry Sweeny's article at
mentions a part number suffix that distinguishes two choices but this
doesn't appear in the main datasheet. Other writers here have in the past
mentioned that the suffix has no predefined meaning and is used only to
distinguish design variants internally.
It appears that Isotemp do offer a choice of voltage options but don't like
to document it publicly. Tom Miller's strategy seems the safest if using a
On Fri, Oct 28, 2016 at 8:10 PM, Peter Reilley <preilley_454 at comcast.net>
> 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
> All the eBay units that look the same say 12 volts.
> 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.
>> 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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