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

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 […]

App note: Microcontroller Clock – crystal, resonator, RC Oscillator, or silicon oscillator?

App note from Maxim Integrated on clock sources of microcontrollers and their strengths and weaknesses. Link here The majority of clock sources for microcontrollers can be grouped into two types: those based on mechanical resonant devices, such as crystals and ceramic resonators, and those based on electrical phase-shift circuits such as RC (resistor, capacitor) oscillators. […]

App note: Best design and layout practices for SiTime oscillators

SiTime’s app note about how to properly route an oscillator’s PCB traces. Link here Proper decoupling, bypassing, and power supply noise reduction is important in many applications to ensure optimal performance for oscillators. A common strategy is to place capacitors near high speed devices on a printed circuit board (PCB). These capacitors serve important functions: […]

Simple crystal tester

Dilshan Jayakody writes: This is simple Colpitts oscillator to test commonly available passive crystals which range between 2MHz to 27MHz. This unit must connect to an oscilloscope and/or frequency counter to get the frequency of the crystal. This circuit is design to work around 9V to 12V DC power source. Both 2SC930 transistors can replace […]

Building a better RTL-SDR TCXO

Craig posted an article describing how he built a 28.8MHz RTL-SDR TCXO, that is available on github: Here’s a scratch-built 28.8MHz TCXO capable of +-1ppm stability from 0C-55C; best of all, it’s not only easy to build, but is designed entirely from readily available and inexpensive components. For improved temperature stability, the main oscillator can […]

Audio oscillator with frequency counter

Xristost blogged about his DIY Audio oscillator with frequency counter project: After I finished the oscillator, I made some minor changes in the square signal part of the schematic. I connected five of the inverters in parallel with low value load resistors, thus reducing the influence of the parasitic capacitance of the PCB. The goal is […]

BFO for SSB reception

Dilshan Jayakody writes: This post is about beat frequency oscillator (BFO) module which is used to receive SSB and CW signals from ordinary shortwave receiver. The original circuit which is related to this post is obtained through the internet and we modify it to get more precise output with commonly available electronic components. (Unfortunately at the […]

ATMega328 RC vs quartz oscillator comparison

Kenneth compares the RC oscillator found on the ATMeg328 against an external quartz crystal. As expected there is a huge difference in precision and stability between the two. This really demonstrates how both oscillators, but particularly the internal one, are very sensitive to temperature changes around the microcontroller.  This is why my counter’s oscillator is […]

7400 competition entry: FM modulation and demodulation system

Alifred and his friend entered a FM modulation, demodulation and transmission system into the Open 7400 Logic Competition. An input waveform enters the Voltage Controlled Oscillator (VCO), resulting in a FM modulated waveform. This is then sent to an IR LED (through a buffering MOSFET) and is received by a photo-transistor at the other end. […]