Depending on where you’re starting, adding an OCXO could improve your frequency tolerance by 1 to 3 orders of magnitude. Oven controlled oscillators keep the crystal at a stable temperature which in turn improves frequency stability. We have seen perform a similar upgrade to his HP 53151A, however, this circuit is more generic and can be lashed up on a small section of solderable perf board. shares his design and fabrication instructions for a DIY OCXO circuit he made for his Racal-Dana frequency counter. If you have an old “Racal-Dana 199x” frequency counter or similar 10 MHz internally referenced gear with a poor tolerance “standard quartz crystal oscillator” or bit better “temperature compensated crystal oscillator” (TCXO) you could upgrade to a high stability timebase “oven controlled crystal oscillator” (OCXO) for under $25. Posted in classic hacks Tagged frequency counter, hewlett packard, HP, ocxo, oven controlled crystal oscillator DIY High Stability Timebase Hack For ~$25. One more piece of classic (and still very useful) test equipment brought back to full operation. With the fuse jumped, the oven came to life. The service manual recommended jumping out the fuse for testing. The problem turned out to be a simple thermal fuse. The Darlington transistors used as heaters were fine. ![]() Time to tear open an oven!Īrmed with a copy of the 5350B service manual from HP’s website, opened up his OCXO. If the OCXO was working, wattage would have dropped after about 10 minutes when the oven came up to temperature. checked the wattage of his 5350B, and determined that it pulled about 27 watts at power up and stayed there. Considering it was only a $750 USD upgrade to the 5350B’s $5500 USD base price, it’s not surprising that many 5350B’s in the wild have this option. The 5350B had three time bases available: a Thermally Compensated Crystal Oscillator (TCXO), an Oven Controlled Crystal Oscillator (OCXO), and a high stability OCXO. In the process, he gave us some great pictures of late 80’s vintage HP iron.Įverything seemed to be in relatively good working order, with the exception of the oven indicator, which never turned off. A true fan of Hackaday Prize judge , didn’t turn it on, he took it apart. This baby will go 10Hz all the way up to 20GHz with only one input shift. Not just any counter, a classic Hewlett-Packard 5350B Microwave Counter. recently got himself a frequency counter. That’s a win in our book.Ĭontinue reading “Nanocounter: Frequency Counter With An Android UI” → Posted in Tool Hacks Tagged android, bluetooth, fpga, frequency counter, TCXO XOXO For The OCXO ( Classic yak shaving!) But the result is a great read of a detailed writeup, and you can watch a video of the Nanocounter in action after the break. The project achieves the goal of frequency counting, though doesn’t remember what project sparked the idea to build it. Finally, a cheap HC-06 Bluetooth module facilitates communication with an Android device. ![]() ![]() A STM32F072 microcontroller uses a SPI interface to get this data out of the FPGA, and controls the whole system. This reference clock, along with the signal to be measured, are sent into a Xilinx FPGA which uses a method called equal precision measurement to determine the frequency. ![]() It’s based on a high accuracy temperature compensated crystal oscillator (TCXO) fed into a phase locked loop (PLL) to create a high frequency, accurate reference clock. The Nanocounter is an accurate, open source frequency counter that uses an Android phone as its display. Most people would just buy a frequency counter and be done with it, but decided to build his own. Have you ever started a project, run into an issue, started a new project to solve the issue, and completely forgot about the original project? went down a rabbit hole of needing a tool to calibrate an MCU oscillator, but not having an accurate way to measure frequency.
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