This page lists my Open Hardware electronics designs. Most newer designs have KiCad schematic, PCB-layout, and gerber-files available. Please ask if you are interested in the older designs - some may be available.
Low noise preamplifier, AC-coupled 0.1 Hz to 1 MHz. Input-referred voltage noise is well below 50R resistor at room temperature (0.9 nV/sqrt(Hz)), if the source impedance is low. Input stage is 16pcs ADA4898 op-amps in parallel - current-consumption and heating quite large. https://github.com/aewallin/ADA4898_LNA
Two-stage OPA818 Photodetector
OPA818-based transimpedance amplifier, followed by 2nd-stage gain. Used for PDH-locking lasers to FP-cavities. https://github.com/aewallin/Photodetector_2stage_OPA818
One Inch Photodetector
Single op-amp transimpedance amplifier for TO-18 footprint photodiode, on a PCB that fits a 1" lens-mount. PCB-variants for SOT23, WSON8, OPA818 op-amps. Output-buffered (BUF602) versions work better than single op-amp versions.
Loops back the RX-signal on the SFP to the TX-pins. A limiting amplifier provides differential outputs that allow monitoring the signal through the SFP.
Simple SFP breakout board: https://github.com/aewallin/SFP-Breakout-Board . Provides +3V3 power to the SFP, and direct access to the differential TX/RX pins. Three status LEDs. No access to the I2C memory on the SFP.
The fourth revision of a simple board for E/O and O/E conversion of RF signals using telecom SFP transcievers. Works from 10 MHz (and probably much lower) up to at least 500 MHz. Standard SFPs go up to 1 Gbit (1.25 MHz) but this board will probably not work much over 500 MHz. One input, two identical outputs. Either SMA or BNC connectors.
Now on github: https://github.com/aewallin/SFP2SMA_2018.03
PICDIV, 2018 update
An update to the PICDIV frequency divider circuit. The input is a two-transistor sine-to-square circuit, taking 10MHz sinewave and turning it into a clock-signal for the PIC. The PIC has DIP-switches for selecting 1e7, 1e6, or 1e5 division, which produces 1Hz, 10Hz, or 1kHz output from a 10MHz input. There are two outputs buffered by high-speed LVCMOS buffers - with trimmer-caps for adjusting output-skew.
Frequency distribution amplifier (2017-2018)
Pulse distribution amplifier (2017-2018)
Isolated pulse distribution amplifier
A 1:4 pulse-distribution amplifier for 1PPS with an optoisolator-input providing galvanic isolation.
RF SP8T 1+ GHz multiplexer
A 1:8 absorptive SP8T RF-multiplexer, with SPI interface. Based on TE HF3 relays. > 1 GHz bandwidth. The prototypes use an Arduino Due + Ethernet Shield for control.
DIY DSOXLAN (2015)
Simple Ethernet/LAN interface card for a HP/Keysight DSOX 2000/3000 oscilloscopes.
Constant-current TEC drive (2014)
HVDC amp (2013)
PICDIV frequency divider (2016)
10MHz input, 1PPS output, based on Tom van Baak's picDIV code.
PID controller (2014)
Simple analog op-amp based PID-controller with jumpers for selecting P/I/D gains and trimmer-potentiometers for a weighted sum of P/I/D.
These projects are not yet on this page.
- Pulse-stretcher (2014). 10ns or shorter pulse in (from e.g. PMT photomultiplier single photon detector), 100ns or longer pulse out.
- Agilent 34901A and 34907A breakout boards. Breakout from 40-pin ribbon cable to BNC and D-sub connectors.
- Pt100 tempereature measurement frontend. 4-wire pt100 frontend driving constant current through the sensor and amplifying the voltage drop to +/-10V for a DMM-measurement.
- Photodiode amplifier (various..)
- 8-channel 4th-order 60 kHz anti-alias low-pass filter (2008). For the ADC input of an NI DAQ-card. (old, source-files probably not recoverable)
- Optoisolator for Mesa 5i20 servocard (2006). For CNC machine control. (old, source-files probably not recoverable)