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Electronics => Projects, Designs, and Technical Stuff => Topic started by: daveyk on November 22, 2021, 10:45:21 pm

Title: Is there a 60Hz Oscillator?
Post by: daveyk on November 22, 2021, 10:45:21 pm
Not wanting to rely on the power line frequency to be stable or free of noise, or evan the mains.  I would like to build a tiny 60Hz sinewave circuit, ~5V P-P, or 5volts Peak (only need to use positive).

On Mouser or Digikey, I can not find an oscillator that is 60Hz or a multiple of 60 Hz, to divide down.

Title: Re: Is there a 60Hz Oscillator?
Post by: floobydust on November 22, 2021, 11:05:51 pm
You need crystal-controlled accuracy? It's a hassle because divider IC's are to the power of 2, so 60Hz is a hassle.
The old, obsolete part is the MM5369 (http://www.riana.com/electronics/docs/MM5369.pdf) using TV colour burst crystal 3.579545MHz giving low uneven duty-cycle 60Hz square-wave.
Replacement using PIC12C508 An Enhanced MM5369 - 60 MHz Generator (https://ww1.microchip.com/downloads/en/appnotes/4_008.pdf)
I have seen one-transistor 60Hz phase-shift oscillator fed the divided down xtal square-wave input, to convert to sine.
Title: Re: Is there a 60Hz Oscillator?
Post by: dom0 on November 22, 2021, 11:07:05 pm
Use a  6.144  MHz quartz and divide 2**12, then divide by 5 two times (there's a few parts in the 74xx series that do this).

Modern way: any quartz + DDS chip, especially if you want it to be sinusoidal. Or pretty much any MCU clocked from a quartz. It's just 60 Hz after all.
Title: Re: Is there a 60Hz Oscillator?
Post by: TimFox on November 22, 2021, 11:22:34 pm
Technically, dividing the color burst frequency gives you 59.94 Hz (NTSC rate, different from b/w rate of 60 Hz).
Probably the best way to get a clean 60 Hz sine wave is a DDS synthesizer operating at a clock rate that greatly oversamples the 60 Hz result, making it easy to filter.
Title: Re: Is there a 60Hz Oscillator?
Post by: mag_therm on November 22, 2021, 11:51:11 pm
Epson SG 8018 oscillators ( 3.3 V)  ordered from Dove, etc , pre programmed on the online form to your frequency specified / piece for a few $.
Divide down and get a 50% duty at your frequency.
Check the data sheet for the tolerance,
 however I am using these on HF radio and the first one at 23 C is too close to wwv  to measure with my gear here.
Title: Re: Is there a 60Hz Oscillator?
Post by: bdunham7 on November 23, 2021, 12:29:39 am
Quote from: daveyk on November 22, 2021, 10:45:21 pm
Not wanting to rely on the power line frequency to be stable or free of noise, or evan the mains.  I would like to build a tiny 60Hz sinewave circuit, ~5V P-P, or 5volts Peak (only need to use positive).

On Mouser or Digikey, I can not find an oscillator that is 60Hz or a multiple of 60 Hz, to divide down.

What do you need in terms of short and long term stability?
Title: Re: Is there a 60Hz Oscillator?
Post by: langwadt on November 23, 2021, 12:51:03 am
random mcu and an oscillator as accurate as you want it
Title: Re: Is there a 60Hz Oscillator?
Post by: EPAIII on November 23, 2021, 02:04:55 am
ICs are not always just by powers of two. Well, they are, but there are ICs which can be reset at any count, so you just count up to your frequency / 60 and use that point for the reset. And those reset pulses will be 60 Hz. This is how phase locked loops can be locked to any frequency while using available crystals.

You just need to research the available logic chips.

OR, use a PIC or PIC like device to do it with code.

PS: Crystals can be ordered to the frequency you want. Just go to a good electronic supply house instead of unknown web based sources.



Quote from: floobydust on November 22, 2021, 11:05:51 pm
You need crystal-controlled accuracy? It's a hassle because divider IC's are to the power of 2, so 60Hz is a hassle.
The old, obsolete part is the MM5369 (http://www.riana.com/electronics/docs/MM5369.pdf) using TV colour burst crystal 3.579545MHz giving low uneven duty-cycle 60Hz square-wave.
Replacement using PIC12C508 An Enhanced MM5369 - 60 MHz Generator (https://ww1.microchip.com/downloads/en/appnotes/4_008.pdf)
I have seen one-transistor 60Hz phase-shift oscillator fed the divided down xtal square-wave input, to convert to sine.
Title: Re: Is there a 60Hz Oscillator?
Post by: EPAIII on November 23, 2021, 02:16:41 am
If you are going to use the power line frequency, you MUST understand that there is a difference between short and long term accuracy.

For long term accuracy, the US power grid is far, far, FAR more accurate than any crystal you can buy, even those with ovens. The US power grid's frequency is adjusted so that over a period of one or more DAYS, it will be dead accurate when compared to the WWV signals, which are the public standard in the US. A clock that uses the power grid's frequency will, over long terms, not gain or lose even a single second. So you can set your clock today and one year later it will be dead on (+/- the short term drift that is allowed).

However, in the short term, like up to several hours, that same power grid will drift both faster and slower by a significant amount. Peak demand for electricity will slow the generators, usually in the day and evening time periods and then they will be run faster overnight when the demand is less to gain back the lost time. I am sure they use WWV for this purpose so long term, the generators keep up with the WWV time.

So, you have to ask yourself what do you want, short or long term accuracy. Then choose your method.

And if you want both, then the ultimate method may be the use of a WWV receiver. I have a clock that synchronizes with WWV here in my office. It cost less than $25. But it does not have an output.



Quote from: bdunham7 on November 23, 2021, 12:29:39 am
Quote from: daveyk on November 22, 2021, 10:45:21 pm
Not wanting to rely on the power line frequency to be stable or free of noise, or evan the mains.  I would like to build a tiny 60Hz sinewave circuit, ~5V P-P, or 5volts Peak (only need to use positive).

On Mouser or Digikey, I can not find an oscillator that is 60Hz or a multiple of 60 Hz, to divide down.

What do you need in terms of short and long term stability?
Title: Re: Is there a 60Hz Oscillator?
Post by: antenna on November 23, 2021, 03:09:52 am
Could you make some sort of mechanical or acoustical device like a weighted spring with electromagnetic feedback or a tuned pipe excited with a stream of air inside a soundproofed and thermally stable box with a typical microphone and audio amplifier coupling the signal to the outside?  Without going higher in frequency first, maybe starting with electricity is a poor option.  I wonder how stable a flute's frequency would be if the air temp inside the box was controlled with something like a LM35 temp sensor... The source of compressed air would need to travel through a copper coil submerged in temperature-controlled water matching the box temperature but, albeit clunky, would probably be the cleanest and most stable oscillator out there (not counting the harmonics of a real flute, instrument harmonic research needed!) :)
Title: Re: Is there a 60Hz Oscillator?
Post by: Alex Eisenhut on November 23, 2021, 03:45:55 am
Well, there was, 35 years ago.

https://www.datasheetq.com/LQT-60X-1-doc-Unspecified (https://www.datasheetq.com/LQT-60X-1-doc-Unspecified)
Title: Re: Is there a 60Hz Oscillator?
Post by: nfmax on November 23, 2021, 08:48:26 am
Digikey has loads of 2.4576 MHz crystals listed. They are intended to generate standard Baud rate clocks for serial communication. Since 2.4576 MHz = 60 Hz * (4096 * 10), it should be straightforward enough to build a 60Hz source using one such.
Title: Re: Is there a 60Hz Oscillator?
Post by: timenutgoblin on November 23, 2021, 11:05:00 am
The suggestion above regarding the 3579545Hz quartz crystal oscillator and the MOD-59659 counter could work quite well if and only if the quartz crystal oscillator is tuned to 3579540Hz (instead of 3579545Hz). Dividing 3579540Hz by 59659 generates 60Hz. Otherwise, at 3579545Hz, the clock pulses would arrive sooner rather than on-time.

If the quartz crystal oscillator is 3579545Hz then the 1-second pulse will arrive at:

5/3579545 ~ 1396.8255742ns before it is due. It would take:

3579545/5 ~ 715909 seconds until the seconds are synchronized with correct time. This is equivalent to:

8 days, 6 hours, 51 minutes and 49 seconds when the clock would gain exactly 1 second. (I think...)
Title: Re: Is there a 60Hz Oscillator?
Post by: Siwastaja on November 23, 2021, 11:51:56 am
Because you want sine, any dedicated DDS chip, or any microcontroller with simple DDS software implementation.

The project doesn't need to be complicated, pick a microcontroller with DAC, pre-calculate the sine wave in look up table and just run through the table in a timer interrupt, at a high rate, like one million samples per second. Then you just need a tiny bit of RC filtering to get rid of the tiny steps and create smooth sine wave.
Title: Re: Is there a 60Hz Oscillator?
Post by: Renate on November 23, 2021, 06:53:43 pm
Eh, what's so great about 60 Hz anyway?
Can't you hack the circuit to use 1 Hz? If you really can't you can make a circuit that turns 1 Hz into 60 Hz. No, not a PLL, that's too complicated. For instance, it takes a trigger and sends out 60 cycles, changing once every millisecond equals 120 milliseconds. If you are feeding that to your (non mechanical) night table alarm clock it will work just fine.
What's so great about 1 Hz? You can get that from (most any) cheapy GPS module and at an accuracy that will beat anything else.
Title: Re: Is there a 60Hz Oscillator?
Post by: David Hess on November 24, 2021, 06:05:43 pm
7.3728 MHz and 24.000 MHz are easily divided down to 60 Hz.
Title: Re: Is there a 60Hz Oscillator?
Post by: Nusa on November 24, 2021, 07:00:46 pm
There's this that is designed for the job: https://www.elmelectronics.com/ic/elm440/ (https://www.elmelectronics.com/ic/elm440/)

But they're planning to close shop in June, 2022. So buy now if you want any.
Title: Re: Is there a 60Hz Oscillator?
Post by: SiliconWizard on November 24, 2021, 07:44:52 pm
First you may need to tell us what your application is. Why do you need 60 Hz? If it must be at all related to mains power, then whether you want "to rely on the power line frequency" or not doesn't matter, it's the only way you'd get synchronized to it. If that matters.

Now if you actually dont' care bout mains power, then why 60 Hz exactly? Tell us a bit more.
As to getting a sine output - how accurate must it be? What's your requirement in terms of acceptable distortion?
DDS might be overkill here. Possibly a crystal-based oscillator followed by a sharp low-pass filter would do the trick. We need to know more.
Title: Re: Is there a 60Hz Oscillator?
Post by: Renate on November 24, 2021, 07:50:00 pm
Actually, there are quite a few things that divide down to 60 Hz. Here are some.
Code: [Select]
    Xtal    As Factors                      Divisor
--------    ----------------------------    ----------------
   30000    2^4 * 3 * 5^4                   2^2 * 5^3
   31200    2^5 * 3 * 5^2 * 13              2^3 * 5 * 13
   31500    2^2 * 3^2 * 5^3 * 7             3 * 5^2 * 7
   36000    2^5 * 3^2 * 5^3                 2^3 * 3 * 5^2
   38400    2^9 * 3 * 5^2                   2^7 * 5
   60000    2^5 * 3 * 5^4                   2^3 * 5^3
   75000    2^3 * 3 * 5^5                   2 * 5^4
   76800    2^10 * 3 * 5^2                  2^8 * 5
   96000    2^8 * 3 * 5^3                   2^6 * 5^2
  111000    2^3 * 3 * 5^3 * 37              2 * 5^2 * 37
  120000    2^6 * 3 * 5^4                   2^4 * 5^3
 1228800    2^14 * 3 * 5^2                  2^12 * 5
 1843200    2^13 * 3^2 * 5^2                2^11 * 3 * 5
 1966080    2^17 * 3 * 5                    2^15
 2304000    2^11 * 3^2 * 5^3                2^9 * 3 * 5^2
 2457600    2^15 * 3 * 5^2                  2^13 * 5
 2949120    2^16 * 3^2 * 5                  2^14 * 3
 3000000    2^6 * 3 * 5^6                   2^4 * 5^5
 3686400    2^14 * 3^2 * 5^2                2^12 * 3 * 5
 3932160    2^18 * 3 * 5                    2^16
 4032000    2^9 * 3^2 * 5^3 * 7             2^7 * 3 * 5^2 * 7
 4608000    2^12 * 3^2 * 5^3                2^10 * 3 * 5^2
 4915200    2^16 * 3 * 5^2                  2^14 * 5
 5068800    2^11 * 3^2 * 5^2 * 11           2^9 * 3 * 5 * 11
 5990400    2^11 * 3^2 * 5^2 * 13           2^9 * 3 * 5 * 13
 6000000    2^7 * 3 * 5^6                   2^5 * 5^5
 6144000    2^14 * 3 * 5^3                  2^12 * 5^2
 7200000    2^8 * 3^2 * 5^5                 2^6 * 3 * 5^4
 7372800    2^15 * 3^2 * 5^2                2^13 * 3 * 5
 7680000    2^12 * 3 * 5^4                  2^10 * 5^3
 9000000    2^6 * 3^2 * 5^6                 2^4 * 3 * 5^5
 9216000    2^13 * 3^2 * 5^3                2^11 * 3 * 5^2
 9600000    2^10 * 3 * 5^5                  2^8 * 5^4
 9830400    2^17 * 3 * 5^2                  2^15 * 5
11046000    2^4 * 3 * 5^3 * 7 * 263         2^2 * 5^2 * 7 * 263
11059200    2^14 * 3^3 * 5^2                2^12 * 3^2 * 5
12000000    2^8 * 3 * 5^6                   2^6 * 5^5
12096000    2^9 * 3^3 * 5^3 * 7             2^7 * 3^2 * 5^2 * 7
12288000    2^15 * 3 * 5^3                  2^13 * 5^2
12480000    2^9 * 3 * 5^4 * 13              2^7 * 5^3 * 13
13500000    2^5 * 3^3 * 5^6                 2^3 * 3^2 * 5^5
13516800    2^14 * 3 * 5^2 * 11             2^12 * 5 * 11
14745600    2^16 * 3^2 * 5^2                2^14 * 3 * 5
15000000    2^6 * 3 * 5^7                   2^4 * 5^6
15360000    2^13 * 3 * 5^4                  2^11 * 5^3
15974400    2^14 * 3 * 5^2 * 13             2^12 * 5 * 13
16257000    2^3 * 3 * 5^3 * 5419            2 * 5^2 * 5419
17430000    2^4 * 3 * 5^4 * 7 * 83          2^2 * 5^3 * 7 * 83
18000000    2^7 * 3^2 * 5^6                 2^5 * 3 * 5^5
18432000    2^14 * 3^2 * 5^3                2^12 * 3 * 5^2
19660800    2^18 * 3 * 5^2                  2^16 * 5
22118400    2^15 * 3^3 * 5^2                2^13 * 3^2 * 5
23592000    2^6 * 3 * 5^3 * 983             2^4 * 5^2 * 983
24000000    2^9 * 3 * 5^6                   2^7 * 5^5
24576000    2^16 * 3 * 5^3                  2^14 * 5^2
27000000    2^6 * 3^3 * 5^6                 2^4 * 3^2 * 5^5
30000000    2^7 * 3 * 5^7                   2^5 * 5^6
32514000    2^4 * 3 * 5^3 * 5419            2^2 * 5^2 * 5419
33000000    2^6 * 3 * 5^6 * 11              2^4 * 5^5 * 11
36000000    2^8 * 3^2 * 5^6                 2^6 * 3 * 5^5
42000000    2^7 * 3 * 5^6 * 7               2^5 * 5^5 * 7
48000000    2^10 * 3 * 5^6                  2^8 * 5^5
49860000    2^5 * 3^2 * 5^4 * 277           2^3 * 3 * 5^3 * 277
60000000    2^8 * 3 * 5^7                   2^6 * 5^6
A rubidium standard might be overkill, but it's hard to tell. Maybe a hydrogen maser?
Title: Re: Is there a 60Hz Oscillator?
Post by: Benta on November 24, 2021, 09:02:55 pm
As the OP hasn't responded since two days, this subject is moot.
Title: Re: Is there a 60Hz Oscillator?
Post by: timenutgoblin on November 24, 2021, 10:42:49 pm
Quote from: daveyk on November 22, 2021, 10:45:21 pm
Not wanting to rely on the power line frequency to be stable or free of noise, or evan the mains.  I would like to build a tiny 60Hz sinewave circuit, ~5V P-P, or 5volts Peak (only need to use positive).

On Mouser or Digikey, I can not find an oscillator that is 60Hz or a multiple of 60 Hz, to divide down.

Are you familiar with Wein Bridge Oscillators? They are capable of producing a sinusoidal wave (with low distortion).

Here is a link to AN-31 Op Amp circuits:
https://web.ece.ucsb.edu/Faculty/rodwell/Classes/ece2c/resources/an-31.pdf

If you choose a capacitor value of 180nF or maybe 177nF (150nF in parallel with 27nF) and a resistor value of 15k this will get you close to 60Hz.

Alternatively, a 22k resistor in parallel with 44.635k using a 100k dual-gang type potentiometer and a 180nF capacitor would provide adjustability around 60Hz. However, the circuit will likely have parasitic capacitance influencing the value of the 100k potentiometer wiper resistance.

A 180nF capacitor in combination with 22k || 44.635k = 14.737k gives ~60Hz.

This type of circuit can be powered from single rail power supply, but it should be noted that in the examples given, the earth/ground points need to be connected to Vcc/2 if the op-amp is powered from a single rail power supply.
Title: Re: Is there a 60Hz Oscillator?
Post by: TimFox on November 24, 2021, 10:53:46 pm
Not your fault, since even National Semiconductor made this common mistake, but the correct term is "Wien Bridge", not "Wein Bridge".
German is very consistent in pronouncing "ie" vs. "ei", and "Wein" is German for "wine".
Max Wien invented this bridge in 1891:  it is one of many useful AC bridge circuits, and can be used either to measure capacitance or frequency.
It was used in audio oscillators starting shortly before WW II, perhaps the first one by H H Scott at General Radio in 1938.  (General Radio was more interested in heterodyne audio sources, which could be swept in one turn of the control, so they only took this up seriously after Hewlett and Packard commercialized their design in 1939.)
Title: Re: Is there a 60Hz Oscillator?
Post by: DrG on November 25, 2021, 12:17:06 am
Quote from: Nusa on November 24, 2021, 07:00:46 pm
There's this that is designed for the job: https://www.elmelectronics.com/ic/elm440/ (https://www.elmelectronics.com/ic/elm440/)

But they're planning to close shop in June, 2022. So buy now if you want any.

That is interesting - it's a PIC125XX and can synch to 60Hz line for correction (according to the data sheet which is (C) 1999). I'd love to see the code.
Title: Re: Is there a 60Hz Oscillator?
Post by: floobydust on November 25, 2021, 01:17:56 am
Microchip app note 4_008 (https://ww1.microchip.com/downloads/en/appnotes/4_008.pdf) I mentioned in post #1 contains the 12C508 assembly language code. Their website search engine is terrible, I could not find the text to post here. It looks good:

"... Sync-lock is achieved by allowing a high-to-low signal at GP2 to reset the main counter,  TMR0. As long as these transitions occur, the output will continue to follow the input, and the output will have exactly the same frequency as the line frequency. As this is traceable back to national standards, it is better as a long-term reference than the crystal. As to deciding which source to use for the output, a very narrow window is set up to detect whether a 60 Hz sync pulse occurred before the timer timed out, or not. This allows an AC failure to be detected during the cycle that it failed, and a 3.58 MHz derived one to be inserted with no loss of output cycles.
The narrow window does slow sync-lock down considerably, however, on return of AC, typically taking about 30 seconds to regain lock. (If the two frequencies were identical, but only differed in phase, the circuit could theoretically never return to sync-lock)."
Title: Re: Is there a 60Hz Oscillator?
Post by: tooki on November 29, 2021, 09:42:05 pm
Quote from: Nusa on November 24, 2021, 07:00:46 pm
There's this that is designed for the job: https://www.elmelectronics.com/ic/elm440/ (https://www.elmelectronics.com/ic/elm440/)

But they're planning to close shop in June, 2022. So buy now if you want any.
Quite a feat, running a company entirely around chips that are actually just programmed PIC microcontrollers!