I've always used the internal oscillator in my AVR microcontroller projects, but have discovered that I need to use an external oscillator to increase the clock frequency. I have some of these 20MHz crystals in the spare parts bin, but I can't find a datasheet.

Searches for "MPC" and "970T" aren't providing any useful hits. I'm brand new to using crystals, and as such I am going to have a bit of work ahead to learn the ropes. Before I can get started I'd like to at least try using the ones I have on hand.

Do you recognize the logo or markings on this part, and if so can you point me in the right direction?


This is a 4-pin device which is why I believe it is a crystal oscillator rather than just a crystal.

20MHz crystal oscillator

  • \$\begingroup\$ @PeterJ Yes it does. I'm discovering this is a crystal oscillator as opposed to a standard crystal with 2 pins. (Which explains its size compared to smaller ones I've seen.) \$\endgroup\$
    – JYelton
    Jul 31, 2013 at 6:43
  • \$\begingroup\$ Some useful information on crystals for AVR uses: avrfreaks.net/… \$\endgroup\$
    – JYelton
    Jul 31, 2013 at 6:46
  • 1
    \$\begingroup\$ I thought XOs all had the same pinout (Vcc at 14, GND at 7, Out at 8). \$\endgroup\$ Jul 31, 2013 at 6:50
  • \$\begingroup\$ Sorry I'd removed my comment about it being an oscillator module, I had a facepalm moment and read the title as crystal \$\endgroup\$
    – PeterJ
    Jul 31, 2013 at 6:50
  • \$\begingroup\$ @PeterJ It's ok, you prompted me to include the note about it having 4 pins. \$\endgroup\$
    – JYelton
    Jul 31, 2013 at 6:51

1 Answer 1


Found it. MPC is Monitor Products Company, bought out by MMD Components (MMD Monitor/Quartztek Frequency Control Products) in 2002.

970T Datasheet Low-Cost, Full-Size TTL-compatible Clock Oscillator

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    \$\begingroup\$ You'll have to share your Google-Fu secrets, I couldn't find this (and I am generally pretty decent finding things!). \$\endgroup\$
    – JYelton
    Jul 31, 2013 at 6:53
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    \$\begingroup\$ @Jyelton googled 'M PC Crystals', found an ebay auction with a similar product, and datasheet. Lead me to Monitor Products Company, who's website is gone. So I searched for their name and city, which lead me to a company profile mentioning MMD Components. Knowing companies get swallowed all the time, once I searched that, the Monitor name was in MMD's name (Like Maxim-Dallas did to Dallas). Also, for the datasheet, all I had to find was Monitor Products Company 970T. First hit. \$\endgroup\$
    – Passerby
    Jul 31, 2013 at 6:58
  • \$\begingroup\$ I see; I saw the ebay links but didn't think to go there. Perhaps because I've encountered a fair number of things there with no useful links. Much thanks for your help. \$\endgroup\$
    – JYelton
    Jul 31, 2013 at 7:05

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