A Little Background
As an Electrical Engineer by day, and a “wanna-be” microscope technician on weekends, the development of the BHT/U_LED Illuminator for the BHT/BHTU was probably inevitable. However, proudly considering myself a card-carrying, halogen-purist snob, I put this project off for about as long as I possibly could. Why the procrastination? In my mind, “the BH2 should use halogen lighting, as God intended”. The very thought of an LED illuminator on a BH2 felt like blasphemy to me.

Then one day out of the blue, a microscope friend in Australia contacted me and said he wanted to send me one of his LED illuminators he had made for the BH2 scope, absolutely free of charge (and international shipping is not cheap!). Of course, the Halogen Grinch in me recoiled at the thought of an LED on a BH2, but nonetheless I accepted James’ generous offer. The package soon arrived from Australia, and it contained a crude, hand-made illuminator with an LED screwed onto the top of a hand-cut aluminum block functioning as the heatsink. I lined up the wooden alignment pins that James has meticulously sanded to fit and plugged it into my old “Crash Test Dummy” BHTU scope, using the instructions James had provided. Then I took a deep breath and fired it up.

I must confess, I was immediately and totally blown away. What I saw was totally unlike my prior experiences with LED microscopes from just a few years earlier, and this Halogen Grinch’s heart grew three sizes that day! Crash Test Dummy was making BEAUTIFUL images with the hand-made LED rig that James had sent me. The gift James sent came at a really good time, since the year prior (2025), Evident had announced the discontinuation of the LS20H (5S-119) halogen lamphouse, and supplies of the LS20H on the used markets were quickly drying up.

A huge thanks go to James Indsto, for growing this Grinch’s heart. Somehow, the small hoard of LS20H lamphouses that I have been slowly accumulating ever since Evident’s announcement of the discontinuation doesn’t seem so important anymore. I plan to use LED lighting on my main BH2 scope from now on. Why should I put up with the 200-hour lifetime of the ESB lamp? Why should I put up with a color temperature that varies with every setting of the intensity slide? Why should I put up with all of that heat?

Thanks also to Eric Sprehe for very generously providing the custom machine work needed to get to a working prototype that actually fits well on the BH2 microscope, and to Joe Haralson for helping me beta test this thing, and for telling my that the early prototype units did not fit his scope!