Shared Projects

IC eval board

(experimental and as yet untested)

This is a differential buffer for connecting cheap voltmeters (for example: https://amazon.com/CenryKay-4-5-30v-Digital-Display-Voltmeter/dp/B08PB5NDMC) to the individual sticks of a Honda hybrid car’s IMA battery pack. The battery pack of a Honda hybrid car has 120 NiMH D-cells arranged in 20 sticks of 6 cells each. The cable running from the battery pack to the BCM (Battery Condition Monitor) has voltage sense taps for every two sticks. We tried attaching ten of the cheap voltmeters to these sense lines. The voltmeters have only two wires, which are used for both sensing the voltage and powering the meter. The problem is that it seems the taps are not tied directly to the battery – there must be some sort of current limiting resistor in each wire. The current drain of the voltmeters is enough that it changes the voltage read by the BCM, which throws a hissy fit and shuts down the hybrid assist system.

Here are some pictures from our first attempt: https://www.insightcentral.net/threads/yet-another-ima-problem-post.130739/page-2

This experiment uses a high impedance differential amplifier to read the voltage across each pair of sticks, and translate that to a ground referenced voltage with enough drive to run each voltmeter. The maximum voltage that might come out of the battery is less than 200 volts with respect to ground. The maximum differential across each pair of sticks is around 19 volts. The buffer that reads the highest stick pair might see inputs at full charge of 184 and 165, with a difference of 19 volts. With these inputs, the buffer would output 19 volts, referenced to vehicle ground, with a drive of around 25 ma to drive the voltmeter.

QSPI flash board for SAM9x75 EVK. Beta release.

Uses MX28F2000 to hold 3 or 4 games. The games are selectable with dip switches.

MVP2 interface

Transistor Radiosonde Balloon Telemetry Transmitter Board Version 2.

Based on the ©1964 design of project #27 from 103 Simple Transistor Circuits for a “Telemetering Transmitter” but added 2nd channel TX control, and filtering for 27 MHz un-licensed ISM Band. Using mostly period technology - keeping BJT only NPN Si types vs. PNP. The only “modern” component added is the white LED Beacon. Definitely overdone.

More details on Github and my site: Project27

Low Frequency filter board for Hafler DH-110 preamplifier to replace C19, C119 capacitor assemblies

Breaks out the SiLabs MINI-S 2x5 debug interface to a standard ARM SWD 2x5 interface and a header with UART TX and RX. A 0 ohm resistor can be used to route either SWO or UART-TX to the ARM SWO pin.

http://frotz.net/projects/silabs-debug-adapter/

Davis ISS Receiver with TFT LCD Display. Uses Moteino with 915MHz RFM69 module.

Simple Transistor Balloon Payload Transmitter Board Version 1. It is a “Modernized” Project #27 from 103 Simple Transistor Circuits ©1964 using NPN Si Transistors vs. the original’s PNP Ge transistors. This was originally intended to be a balloon payload that transmits temperature info on the 11-meter or 10-meter bands. For scale the battery holder is a AAA cell.

PIC Programming adapter. Ver 4 with hole revisions to accept ZIF socket up to 20 pins