Electronics repairs & projects, test gear, practical demos & software dev.

I buy faulty gear, fix it, and share what I learn. Your support helps me keep going.

Got faulty test gear you don’t want—or going cheap? Contact me and I’ll give it a second life and make a YouTube video of the repair.

PDVS / PDVS2 / PDVS2mini

I'm the original designer of the PDVS family of Precision Voltage Sources.

PDVS2mini now produced by WryTech.

For PDVS or PDVS2 support, contact me.

I post on X (@IanSJohnston) almost daily—follow for what I’m up to.
Enjoy my work? Donate via PayPal or Patreon.

Latest Articles....
	Video Blog 175 - HP3457A Multimeter TFT Conversion Off the back of my recent ADCMT SMU TFT conversion I thought i'd take a look at trying to do the same on my 3457A. Date: 05/02/25

	Video Blog 173 & 174 - ADCMT 6243 Source Measure Unit TFT LCD Upgrade Parts 1&2 I bought a 6243 SMU in the hope I could retrofit my R6581T TFT upgrade to it! Date: 20/02/26

	Video Blog 171 & 172 - WinGPIB, Major upgrade, the USER tab I've updated WInGPIB with the ability for users to create their own instrument control tab withing GPIB via a simple text based configuration file. Date: 18/12/25

	Video Blog 169 - EEZ BB3 Power Supply Repair (again!) This is the 2nd time my BB3 Bench Power supply has developed a fault, this time errors on the display on startup. Date: 19/11/25

	Video Blog 167, 168 & 170 - Wavetek 1281 8.5" Multimeter Repair - Parts 1, 2 & 3 I received a Wavetek 1281 for repair, the owner having made some attempts prior to sending to me. Date: 27/11/25

	Video Blog 166 - Electronics Related Calculators Lots of work to my website lately, including updating a lot of the electronics related calculators on my website. Date: 03/11/25

	Project 030 - Adding a VPN Server to Pfsense How to add a OpenVPN server to Pfsense. Date: 15/10/25

	Project 029 - Adding a 4G Router as a Failover Internet Connection How to add a 4G router as a backup to your main internet connection via Pfsense. Date: 09/10/25

Latest Articles....