Updating a Hafler DH-110 preamplifier from the early-80’s with new electrolytic capacitors, along with a cleanup and then testing.Continue reading “Hafler DH-110 Preamplifier Refresh”
This is a continuation of my Wien Bridge Oscillator module design project. It houses all the parts needed for a portable Ultra-Low THD dual-frequency sine wave generator.Continue reading “Ultra-Low-THD Sine Wave Generator”
Trouble shooting and performing modifications on a HP 3437A System Voltmeter from 1984.Continue reading “Hewlett Packard 3437A System Voltmeter”
I found myself in need of a very low-distortion 1,000 Hz sine wave
generator for an upcoming project.
A quick search on Ebay found several used pieces of test equipment that met or exceeded my requirements, but were priced at well over $1,000 USD.
I did also find some low-cost China sourced 1 kHz generator boards, but they had a distortion of 0.1% which was way above my 0.005% limit.
My current test gear includes a Keithley 2015 THD Multimeter with a low distortion sine wave generator, but it is only capable of 0.03% THD at 1 kHz.
It was time to see if I could build something for under $100 that would meet my needs.
Another local Ebay find was this Hewlett Packard HP 403B AC Voltmeter in a protective HP vertical case. The case did an excellent job of protecting the meter over it’s now 48 year life.Continue reading “Hewlett Packard HP 403B AC Voltmeter Restoration”
I found myself in need of a rechargeable battery tester, so I went off to search the internet for a DIY tester.
I was pleasantly surprised to find that John Lowen, had built a Rechargeable Battery Capacity Tester (v2.0), and also developed the PC interface software for desktop use.
Even better I found that Paul V. had also built the same tester and had made several improvement in the design and software.
Everyone should have at least two of these ESI 250DE Impedance bridges.
Well that was not my first thought when purchasing this unit on Ebay.
I was still having some issues with the “Internal DC” detector circuit on my existing unit, and the price of this unit was extremely reasonable. After dozens of hours troubleshooting the first unit with no solution, my thought was to compare the two circuits and salvage parts from the new unit if necessary.
An updated version of the Millivolt Meter project from May 2016, with dual range selection, calibration selection, improved software, and updated board layout.Continue reading “Millivolt Meter Version 2”
Finally assembling the electronic load modules for some basic testing of minimum voltage at different current levels, and heatsink thermal capacity.Continue reading “Linear MOSFET Electronic DC Load — Part 2″
Repair and cleanup of a vintage Keithley Instruments 600A Electrometer.Continue reading “Keithley 600A Electrometer Repair”
Cleanup and repair of an ESI Dekastat model DS1463 12K Ohm coaxial decade resistor.Continue reading “ESI Dekastat DS1463 12K decade resistor repair”
Fixing issues with the 4 digit plus mode revision 1.1 multimeter board.Continue reading “Power Designs 6050C Revision 1.2 display update”
Developing a new 4 digit plus mode display for a Power Designs Inc. 6050C power supply capable of displaying current at a milliamp resolution, and voltage at a 10 mV resolution.
Cleanup, repair, and upgrade of a Hewlett Packard (HP)6200B power supply.
Cleanup, repair, calibration check, and display upgrade of a Power Designs Inc. 6050C Universal DC Source.
My latest project is a prototype I2C RGB LCD display board with added EEPROM and some other extras.