Mr. Carlson's Lab Tektronix Battery Pack (222A)

[Smoky]

This weekend's project is to make a battery pack for my Tektronix 222A oscilloscope.

Paul Carlson shows a terrific way of doing it using NiMH AA batteries on YouTube.

Thank you Paul!



First off, Paul used Duracell 2500mAh batteries. I'm using Energizer 2300mAh batteries because that's all that Lowes had on the shelf. Paul explains that since the batteries are used in parallel and in series, that the mAh rating is doubled. The original Lead/Acid battery was 2.1mAh. So I should expect 4.6mAh with the Energizers? Wow!
 







What I used to make spacers with was a thin PVC "Garage Sale" sign





So here are the batteries glued together with Gel Super-glue:





And I got as far as soldering all of the terminals this evening:





...and testing the group of batteries on the multimeter:





These batteries read "pre-charged" on the label. I tested a few beforehand and they read 1.3VDC on the multimeter. So 9.1 VDC sounds about right.

The clip is now attached to the battery pack. I used a length of black 20awg Teflon wire for the ground lead. I routed it through the last pair of cells so that all three wires exit on the same side of the battery once it's wrapped:

[Smoky]

Hey guys, I just finished the battery pack for the small 222A Tektronix oscilloscope!

I cut some pieces of the PVC garage sale sign to tack around the battery pack and create a shell. I wanted to be able to get back into it if need be and I didn't want tape stuck all over it:





I use Shurtape PC857 at work, and it's good, so I wrapped two bands around the shell





The install was easy, and with a couple pieces of little foam blocks to take up some space, she's back together and access is terrific:








Well, I put her right to work! She's attached to the pulsing DC rail of a Realistic APM-300 power meter that I'm working on, or in my case, playing with 





*2 April 2020. It's been two weeks and I'm still on the original charge from the battery! I've used it for about an hour during this time and it works perfectly. I guess this only proves that the battery holds its charge over time, but with its internal auto-shutoff mode activated, who knows when I'll need to put it on its charger

One thing that I did notice immediately was that the waveform appears "cleaner." Before, with the original dead Lead-acid battery installed and the scope being powered by the wall wart, there was plenty of visible noise.

[TERRA Operative]

Nice work!

I went the 18650 battery route in my 224 as in this link:
http://kitsune-denshi.net/projects:tek222bat

What mine looks like now:
https://www.thingiverse.com/thing:3623622

No reason I chose lithium over the ni-mh besides my love for overcomplicating things.

The scope was working perfectly, but in an unrelated fault to the battery pack (which still works perfectly) I've lost half the screen, I think one side of the V-deflection circuitry is busted. One day I'll fix it...