First post, by wiretap
- Rank
- Oldbie
I saw some people on Discord looking for some out of production full can clock oscillators, and they seemed to be very hard to source. But, equivalents were available in surface mount, abeit at a lower voltage.
I came up with a little adapter to replace a full can (5VDC) clock oscillator with a 3.3VDC 7x5mm SMD clock oscillator. It has an onboard voltage regulator to step down 5V to 3.3V to power the clock chip at the right voltage, and it has a level shifter to change the 3.3V clock output to a 5V clock output, sending it back to the system to be read properly. This should open up a ton of options for replacements on obsolete systems where the original part is not available or hard to find.
Rev 0.3 incorporates a clock disable jumper in case your specific board needs to have this clock disabled. (rare occurence) I put a 1x03 2.0mm pitch jumper header onboard for the tri-state "en" input. For the SMD clock to operate, either have a jumper across the "enable" side, or leave it off all together. For disabling the clock, put a jumper across the "dis" pins and make sure the disable jumper is also set on your motherboard/card. I haven't seen any hardware that uses this tri-state input, but I'm sure there may be some out there. If you don't need this feature, don't bother even soldering the pin header on.
For the build, I recommend soldering the clock chip first, then all the back side SMD components, then solder the pin headers. To keep the pins straight, they can be inserted into a spare DIP socket or breadboard while soldering.
KiCAD, gerbers, BOM included for v0.3 in this post.
Boards ordered, but untested as of yet. Please build and test on a breadboard first before use.
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And here's the variable model, which you can program pretty much any frequency, 8kHz to 160MHz. You can use an arduino/pi or any other microcontroller with I2C to set the frequency. It is compatible with both 3.3v and 5v. Components are slightly more difficult to hand solder, but perfectly doable if you are used to working with 0603 size components. This is based on the Adafruit Si5351 Clock Generator Breakout board (LINK), so it can be programmed in the exact some manner. Programming Info.
*this version does not make use of the enable pin, so use in a board that does not utilize clock disable features
