Wolf 5151 Xenon Light Source - Electronics
Yesterday I posted some pictures and thoughts on the Wolf’s optical system. Today, here are a few pictures of the electronics. Let’s start with that big transformer:
I remember checking the coil ratio on this transformers and that it was low, possibly even 1:1. It seemed like it was serving more to isolate the electronics than provide much in the way of a voltage reduction. I assume an isolation transformer maybe desirable for safety reasons given the voltages/currents involved… and ultimate destination of the probe.
Looking at the rest of the system, the lamp housing itself has an interesting looking usage meter:
From what I can tell this is an electro-chemical device, similar to those sold by Curtis and apparently was used as far back as the Apollo missions. It contains a mercury in a capillary tube with a small electrolyte gap kind of floating in the middle. By apply a voltage you can get the mercury to flow through the electrolyte at a well defined rate, to measure the elapsed time.
The main interface uses a number of graph array LEDs, which are used to digitally display the output intensity:
Given that it has a digital readout, and the fact that the PCBs indicate the boards were manufactured in 1992 I expected to find a small microcontroller. But, unless I’m mistaken everything is performed using discrete logic and a few opamps:
This is pretty surprising for a design from 1992. Even in 1992 it would likely have only cost $10 to to just throw a small microcontroller in there to replace all the discrete logic…
However as previously noted, I suspect this design is far older, probably dating the from the late 70s or early 80s. Scientific and medical equipment manufactures tend to be extremely conservative. I’ve seen newly manufactured devices using designs that are at least >30 years old.
It’s also interesting to note that everything is through-hole and all ICs are socketed. Clearly they built this to be easily serviced and repaired probably under a service agreement.
A few other pics are below for reference. Next time, we’ll look at one of my more modern light sources.