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  1. #21
    Junior Member
    Join Date
    Mar 2012
    Posts
    7
    Hi guys

    Currently i am using modded SB Duet, but in the near future I will probably buy and mod SB touuch a little bit.

    I would like to ask for your opinion - what do you think about changing stock clocks for Crystek CCHD-957 and power them up using two LIFEPO4 batteries?
    This battery can supply 3.3V so exactly matches crysteks requirements.
    Crystek clocks need maximum 25ma of current, so one battery could power a clock for approximetely 100h, so its nice.

    What do you think about this idea?

  2. #22
    Do you have a source for the correct frequencies? One of the biggest problems is actually getting the right freq oscillator. The 24.576Mhz is very common and you can now get these from places like RS and Farnell but the 22.579Mhz is not so common and I've not seen it as a stock item anywhere.

    Most of the commercial clocks are using this type of oscillator with a very good low noise fast response regulator circuit to power them. I use a 20ppm abracon for the 24 from RS and I get my 22 from one of the audio clock manufactures. I've never tried to power with a battery. How will you fix the voltage at 3.3v and how will you charge the batts?

  3. #23
    Junior Member
    Join Date
    Mar 2012
    Posts
    7
    I thought that lifepo4 will have 3.3 already fixed [as 3.3 is lifepo4 nominal voltage].
    Do you think that there will be some voltage dropout or fluctuation?

    I was planning to put two batteries [one for each clock] outside [on the back] of SBT, and to put them to seperate charger every ~80h of listening.

  4. #24
    I'm not familiar with the batteries but if they are 3.3v that will be fine. You will need to connect the battery gnds to the touch gnd.

    Those oscillators will also work without the buffer chip U14 as I described in an earlier post which is a definate improvement.

  5. #25
    Senior Member
    Join Date
    Jun 2006
    Posts
    1,690
    Wow, Digikey actually has these in stock at both 22.5792 and 24.576!!!! It looks like these were designed specifically for audio use so they actually carry the standard audio frequencies.

    One interesting aspect of these is that they actually turn the oscillator off when its disabled, so that sounds like a good deal with the scheme of not using a mux, just paralleling the outputs, it sounds like these were specifically designed for that usage.

    I'm going to order myself up a pair and try them out. I have my own regulator designs which I will try as well as batteries.

    John S.

  6. #26
    They are a bit bigger than the oscillators I use so will also be a bit better for DIY. The connection onto the mux output pin will still be a bit tricky, but you could use the TP which could make things a bit easier.

    Did you look to see which mux is for audio and which is for effects? I've not had much time over the past few weeks but i'll have a look while I've got Andy's here

  7. #27
    Junior Member
    Join Date
    Nov 2011
    Location
    Warsaw
    Posts
    15
    Quote Originally Posted by JohnSwenson View Post
    Wow, Digikey actually has these in stock at both 22.5792 and 24.576!!!! It looks like these were designed specifically for audio use so they actually carry the standard audio frequencies.
    John S.
    John,
    can you pls qoute the Digikey part numbers?
    thanks,
    Andy

  8. #28
    I looked last night. They are pretty easy to find using the search function on the site. I just searched for the frequencies 1 at a time

    The specs look fairly similar to the oscillators I use. One thing they do quote that I couldn't find on my own datasheets is phase noise which seems to be one of the things they pushing on the data sheet. I would think that driven by a decent reg, they will be quite good.

  9. #29
    Senior Member
    Join Date
    Jun 2006
    Posts
    1,690
    Quote Originally Posted by brgds View Post
    John,
    can you pls qoute the Digikey part numbers?
    thanks,
    Andy
    Digikey no. Manufacturer no.

    744-1456-ND CCHD-957-25-22.5792
    744-1457-ND CCHD-957-25-24.576

    I ordered mine already and it already shipped, that was fast!

    John S.

  10. #30
    Junior Member
    Join Date
    Nov 2011
    Location
    Warsaw
    Posts
    15
    Many thanks John,
    Andy

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