Agreed. In one extreme case I resurrected a 1502 by ignoring the missing battery compartment and battery, and replacing the duff transformer with a modern 240Vac->12Vdc converter.

Hi Chris, A few messages ago I wrote this: I based this on resistance measurements at the plug but in hindsight I found that 18k to GND somewhat strange. Today I even couldn't position the trace at

Well well well, you are right! How very suboptimum :( I haven't spotted a similar section in the "patriot missile" version. However, I've just tested both my 1502s with two different PSUs. They both

Thanks to Albert and Dave for their responses! I should have looked at the schematic in the manual instead of assuming it had been changed. This also explains why the nuvistor sockets are so far from

Nothing lasts forever. The reflex chargers I built for the Army were for batteries that ranged from 6V through 28V. By their nature, they were made with well balanced strings of cells... as it is

Pretty much everything I have ever seen regarding delta-V bump charging from cell manufacturers or charger makers talk in terms of single cell behavior. It may be easy to design fast delta-V chargers

What R and C did you use for the emulator? I built one awhile back but it doesn't seem to be doing the trick (and I can't remember if it ever did). TekWiki suggests 200 to 270 ohms, 10W, in parallel

5V/0.5V is what you see at the MONITOR jack. Under the hood, it's applied after signal attenuation, and it covers the entire common-mode range regardless of V/Div setting. (It drops to 0.5V on the

I’m not to sure how many series cells are in these. But I’ve never seen a balance charger for NiCD or NiMH as is available for Li chemistry. Some form of trickle charging is required to fully

https://batteryuniversity.com/learn/article/charging_nickel_based_batteries https://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_battery Greg

Dave, You are right, its level is much lower than I remembered. I was thinking it was comparable to the 7A13, but I guess not... I know little to nothing about the Z. -Chuck Harris Dave Wise

Hi Dave- I got tired of nursing those doggone nicads and since I use my 1502 and 1503 mostly where AC is available, I pulled the battery pack and built an emulator to go in its place. Now the TDR

For those who enjoy patent descriptions, here is a link to the Christie Electric Corp.  patent (US4746852A, Ray J. Martin, 1988, filed 1985) which, remarkably, expired today (9/27/2019).  All of the

For what it's worth, I compared the 1967 and 1969 cal procedures, and there's not enough difference to prove a major circuit change at 90000. I don't know why they mentioned it. Dave Wise

Hi Tom, We have the same manuals. I never take the circuit descriptions sections as gospel, as they are written very early in the life of the instrument... often before any have even been made by

Chuck, 1A5 Vc is only 5V. You might be thinking of Type Z, 100V. Chris, I played with my 1A5 in a 545 mainframe and saw what I think you saw. By the way, the manual uses either a 545 or a 545A,

Both my manuals state 10V. They are the PDFs from the web. The 1502 manual with frontpage   "First Printing SEP 1975, Revised AUG 1989" and page 3-13 marked   "rev Jan 86", section

I checked the manual before I wrote my note. The calibration section in my copy of the manual, page 4-11, says: "The NiCad battery pack used in this instrument can be damaged if allowed to discharge

Negative delta V is actually at an astonishingly high voltage in NiCd's. The cell voltage typically reaches 1.9V before it peaks and starts to change direction. The cell will be very hot by that

The Christie papers talk of pulse charging reducing the regularity of crystalline structures formed during charging. They claim that the regular structure reduces the cell capacity over time. Pulse