RJS Electronics Inc.

05/11/2026

Have you ever seen this?
Polarity Reversal??
I have heard of this, but first time seeing it. In the middle of a project this knock off DeWalt Li-ion battery would not charge. Of course I had to see why. In this 5S2P pack, 2 parallel cells are measuring -11.4V! All other cells have expected polarity and voltage.

04/20/2026

Adding a second sensor input to this VOC (Volatile Organic Compound) circuit.

03/11/2026

Solar Batteries in the man cave:

Tripled my capacity adding 2 additional 5KWh server rack batteries.
Totaling 15KWh + 2KWh UPS.

The internal BMS will permit discharge down to 0°F but needs >32°F to charge. There were a couple times this winter it got below 32°F, and could not charge. Built this insulated crate to keep them all cozy, with a 10W heating pad.

03/10/2026

"𝑱𝒐𝒉𝒏 𝒉𝒂𝒔 𝒅𝒐𝒏𝒆 𝒂 𝒈𝒓𝒆𝒂𝒕 𝒋𝒐𝒃 𝒐𝒏 𝒕𝒉𝒆 𝒄𝒊𝒓𝒄𝒖𝒊𝒕 𝒃𝒐𝒂𝒓𝒅 𝒍𝒂𝒚𝒐𝒖𝒕𝒔 𝒇𝒐𝒓 𝒐𝒖𝒓 𝒑𝒓𝒐𝒋𝒆𝒄𝒕𝒔! 𝑯𝒊𝒔 𝒆𝒙𝒑𝒆𝒓𝒕𝒊𝒔𝒆 𝒊𝒔 𝒊𝒎𝒑𝒓𝒆𝒔𝒔𝒊𝒗𝒆."

𝐑𝐨𝐠𝐞𝐫

03/05/2026

"If you are looking for a Knowledgeable Electronics designer and PCB layout Company, contact John at RJS Electronics... John is our go to guy."

Craig

01/26/2026

Another VOC (Volatile Organic Compound) design. This smells for specific chemicals.

01/16/2026

Flash Back Friday #2

Last week we looked at PCB artwork with mylar, tape and stickers from 1989.
This is the PCB that was for. This was hand made, etched, drilled, and plated.
More effort than "connecting the dots" in CAD.

01/12/2026

01/09/2026

Flash Back Friday!

Before CAD, 1989, this is how we would design PCBs.
Light box, mylar, tape and dry transfers, negatives, etching with ferric chloride, and manual drilling.

Took a lot of effort to make a single board.
Anyone else remember those days?

01/06/2026

Celebrating 33 years consulting, designing custom electronics / PCBs / embedded code!

Here is a glimpse of some of my projects over the years.

01/05/2026

interesting

I LOVE getting my mind blown, and blowing all of yours too- here's an app that unlocks the frankly unbelievable instrumentation we've all been carrying aroun...