Open source Agilent 53132A 53131A OCXO ultra high stability oven upgrade

agilent_53131A_53132A_Timebase_us_oven (3)-600

Gaurav Singh made an open source 53132A OCXO Ultra stability time base, that is available on github:

While i was working with my own GPSDO project. i need to have a frequency counter with descent stability so purchased my self a Agilent 53132A which is a 12 digit frequency counter, big brother to 53131A 10 Digit Counter. Both are really nice units.
But they unusable standard Timebase. So optional oven oscillator time base need to purchase. but 53132A and 53131A both unit are no longer available for sale and neither of the Time base upgrades.

See the full post on Embedded Engineering blog.

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Assembly instructions for the STMBL servo drive


Andy Pugh wrote a post on his blog detailing STMBL servo drive assembly:

The main documentation (work in progress) is relevant to both the current and future versions of the drive. However due to the withdrawal from the market of the IRAM256 chip used by the board any future versions are likely to be physically different and assembled differently which is why this is a blog post and not a documentation section.

More details on Bodgesoc Blogsoc blog.

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Free PCB Sunday: Pick your PCB


We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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App note: Introduction to the silicon photomultiplier (SiPM)


App note from ON Semiconductors about SiPM sensors, explaining the working principle and primary performance parameters. Link here (PDF)

The Silicon Photomultiplier (SiPM) is a sensor that addresses the challenge of sensing, timing and quantifying low-light signals down to the single-photon level. Traditionally the province of the Photomultiplier Tube (PMT), the Silicon Photomultiplier now offers a highly attractive alternative that combines the low-light detection capabilities of the PMT while offering all the benefits of a solid-state sensor. The SiPM features low-voltage operation, insensitivity to magnetic fields, mechanical robustness and excellent uniformity of response. Due to these traits, the SensL® SiPM has rapidly gained a proven performance in the fields of medical imaging, hazard and threat detection, biophotonics, high energy physics and LiDAR.

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App note: USB audio bridge example with STM32F0 MCUs


App note from STMicroelectronics using their STM32F0 microcontrollers to playback audio stream from USB. Link here (PDF)

This application note describes a method and an example of synchronizing audio playback or audio recording with an upstream or downstream USB audio host, ensuring flawless audio listening or recording using only internal MCU resources.

Focusing on specific properties of USB microcontrollers from the STM32F0 family, the application note describes how the CRS unit can be beneficially employed for USB audio streaming synchronization. In particular, it elaborates a method of HSI48 clock frequency trimming to compensate for timing differences due to independent USB host (computer) and device (STM32F0) clock domains.

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Free PCB coupon via Facebook to 2 random commenters


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook with a coupon code for the PCB drawer.
  • Limit one PCB per address per month, please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

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How to use I2C LCD with ESP32 on Arduino IDE


A how-to on using an I2C LCD display with the ESP32 using Arduino IDE from Random Nerd Tutorials:

This tutorial shows how to use the I2C LCD (Liquid Crystal Display) with the ESP32 using Arduino IDE. We’ll show you how to wire the display, install the library and try sample code to write text on the LCD: static text, and scroll long messages. You can also use this guide with the ESP8266.

See the full post at

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Hand soldering a WLCSP package

MSOP-10 soldering video at

I admit that when I made the video of me soldering an MSOP-10 package, I did it because I needed to use the chip right away, and didn’t have time to order a breakout board. But this time, I am just doing this for fun.
MSOP is smaller than TSSOP which is smaller than SOIC which is smaller than DIP. Although the pin pitch is larger, the physical size of the ATtiny9 in the charliestar project is smaller than the MSOP-10 package. Most ATtiny parts are also available in QFN format, which has a smaller rectangle with pads around the edges. But there’s a fundamental limit to how close you can put adjacent pins and still have them reflow correctly.

More details at

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DC voltmeter test gadget

test gadfet dcvm-600

DuWayne posted an update on his test gadget project we covered previously:

The picture shows the completed DCVM test gadget in 4 channel mode measuring the 3 voltages present on the headers used to connect the individual test gadgets.  I was running this off of the PC without the 12 volts connected for external power, so I kept the range down to 5 volts.

See the full post on DuWayne’s Place blog.

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