[time-nuts] Re: HP 115BR Clock 60 Hz output option

[Bob Camp]

Hi

If you have a motor that is running at 10 revs a second (600 RPM) and put a 5 slot disk on it. You get 50 Hz 

That motor runs just fine off of 10 Hz. Indeed it might run off 100 Hz or 1KHz, be much smaller, and have a 
10:1 or 100:1 gear box. 

So now we cut one more slot in the disk. Each rev gets you 6 pulses instead of 5.

Bob

> On Mar 7, 2023, at 4:27 PM, Bill Byrom via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Well … no. Dividing 1 kHz by 10 does result in 100 Hz, but changing the division ratio to 6 gets you 166.666… (infinitely repeating decimal fraction) Hz.
> 
> Examination of the prime factors is needed:
> The prime factors of 60 are 2, 3, and 5.
> The prime factors of 100,000 are 2 and 5.
> 
> So you need to account for the 3 prime factor in 60. One way is to multiply the 100 kHz main standard frequency by 3, then divide the 300 kHz resulting signal by 5,000 in the manner you suggest to get 60 Hz. Multiplication by 3 is easy - you just distort the sine wave so it has lots of odd harmonics (such as using a diode rectifier) and send that through a 300 kHz resonant LC tank.
> 
> The oldest piece of HP frequency related gear I ever owned was a HP 524B frequency counter with HP 525B frequency converter. I bought it around 1970 (when I was in high school) and used it for a few years. Wow — it was a huge heavy high wattage beast! If I remember correctly, the ovenized oscillator had drifted past the adjustment range and I used an external frequency reference for the counter. I don’t remember owning any vacuum tube equipment which ran a synchronous clock from a crystal oscillator, but I knew that such products existed. 
> --
> Bill Byrom N5BB
> 
> 
> On Tue, Mar 7, 2023, at 12:01 PM, Jeremy Nichols via time-nuts wrote:
>> Early HP (and other?) frequency standards generated frequency sub-multiples
>> using either regenerative or phantastron dividers. Regenerative dividers
>> are used primarily because they are NOT self starting. If anything
>> interrupts the circuit, the outputs stop, signaling the operator that the
>> clock is now in error.
>> 
>> Phantastron divide-by-10 circuits work by summing pulses, the circuit being
>> constructed so that 10 pulses into the phantastron yields one pulse out.
>> The circuits typically contain adjustable elements allowing the operator to
>> ‘tune’ the circuit for 9, 10, or 11 pulses. It would be easy (he says!) to
>> modify such a circuit to sum 6 pulses instead of 10, before triggering an
>> output pulse. That would get you 60 Hz instead of 100 Hz, for example.
>> 
>> 
>> 
>> On Tue, Mar 7, 2023 at 9:20 AM John Vendely via time-nuts <
>> time-nuts at lists.febo.com> wrote:
>> 
>>> Hi Jeremy,
>>> 
>>> Thanks for the reply.  If nothing else, I'm curious to see how HP
>>> accomplished the 60 cycle output option.  Though trivial today,
>>> synthesizing 60 cycles from the frequencies available in the 115BR
>>> wasn't so convenient back then, given the primarily analog and
>>> rudimentary digital methods available at the time...
>>> 
>>> 73,
>>> 
>>> John K9WT
>>> 
>>> On 3/6/2023 7:24 PM, Jeremy Nichols via time-nuts wrote:
>>>> Sorry I can’t contribute here. My 113AR does not have a 60 Hz output
>>>> option, which could be convenient for running a standard clock. The
>>> outputs
>>>> of my 113AR are half a volt, approximately. A 60 mV output does sound on
>>>> the low side.
>>>> 
>>>> Possibly tvb (Tom Van Baak) will see your message and respond. He has a
>>> 115
>>>> and probably the manual too, although I don’t know if his 115 has the
>>>> option of a 60 Hz output.
>>>> 
>>>> Jeremy
>>>> N6WFO
>>>> 
>>>> 
>>>> 
>>>> On Mon, Mar 6, 2023 at 4:22 AM John Vendely via time-nuts <
>>>> time-nuts at lists.febo.com> wrote:
>>>> 
>>>>> The HP 115BR clock was available with an optional 60 Hz output. The
>>>>> service manual mentions the option but provides no schematic. My 115BR
>>>>> has the 60 Hz output option (a front-panel placard reads "Specif. H08
>>>>> 115R), and after running it for over 30 years, I'm finally getting
>>>>> around to using it to drive a synchronous motor clock via a small
>>>>> class-D power amp and step-up transformer. However, the 60 Hz output
>>>>> level is very low, around 60 mV p-p, and somewhat distorted.  I doubt HP
>>>>> designed it that way.  Before going to the trouble of
>>>>> reverse-engineering it, I thought I'd check to see if anyone has seen a
>>>>> schematic or other information on this option?
>>>>> 
>>>>> Many Thanks,
>>>>> 
>>>>> John
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>> 
>> -- 
>> Jeremy Nichols
>> Sent from my iPad 6.
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