Low-Power Joule Thief Night Light
The classic Joule-Thief circuit can be modified to work in a low-power burst mode: The base resistor R4 is increased to a value that provides just enough base current for startup. After startup, the base current is provided by C1 and transformer L1-L2. Each cycle, the B-E diode of Q1 charges C1 a bit, until[…] Read More…
Keithley 129 Display Repair
The LCD on my Keithley 129 multimeter (which was the first big investment into my electronics hobby ~1982) has turned black over the years. The original LCD is a custom type with zebra-rubber contacts on one side, for which I could not find a source: The standard 3.5 digit displays are too big to fit[…] Read More…
Filament Spool Holder #1
This was the first filament spool holder I built. It is easy to assemble, the required parts are printed quickly and it is flexible enough to acommodate a wide range of filament spool sizes/types. You need: M6 threaded rod, ca. 2* 17cm / 2* 12cm M6 washers and nuts 4* Ball bearing 6mm / 17mm[…] Read More…
My new 3D Printer
3D printing is an interesting topic – after fiddling with a Stepcraft 3D printing head at work, I decided I needed a machine at home to learn the complete process – while milling 2D parts is easy to get into, the 3D printing process still has lots edges, especially when you limit yourself to open-source[…] Read More…
A PLL-based 25MHz OCXO for the FZ7001 Frequency Counter
Running the SI5351A with an external 10MHz reference Update 2017-10-02: Added Firmware archive, see bottom of page Update 2020-11-18: Added notes on generating your own frequencies for external clock on SI5351A Update 2021-06-03: Added Link to Dr. Simon Schrödle’s measurements I own an old ELV FZ7001 frequency counter: However, after I got a used[…] Read More…