bittersweet discovery

Started more testing with my dew heating gear. I needed to know that the new circuit design was correct and could drive a dew strap band. It was strange that I wasn't feeling any heat off the Kendrick 2" dew strap. Tried a direct connection of a heater to battery. Nothing. What?

Tried the custom circuit again. Noticed the CLA LED was not lit. Opened up the Cigarette Lighter Adapter to find a blown fuse! OK. How did that happen? I have a million spares. I loaded in a 5A fast-acting. OK, power was good now. But no heat. Please, no...

Checked the resistance of the 2" heater. It was open. Damn it! Now I have a malfunctioning or dead dew strap. Did I somehow overload a circuit and blow up the 2" eyepiece heater?!

Tested the Kendrick 8" strap - OK! Whew. On the prototype, I found the power transistor, as expected, getting toasty warm. This was good news. Overall, the circuit was correct.

But I was dismayed. Setbacks, frustration, sadness. And there's a distinct possibility there's something wrong with 2" heater.

§

Now I'm wondering... when did this happen? Was it a past issue? Back on 5 Jan '19 in the backyard the 2" heater did not seem to be working.

I dunno. Blown CLA fuse, blown multi-meter fuse... Sure looks like I did something wrong in the last day or two. Gah.

§

Realised the old Micronta digital multi-meter wasn't working right. Opened it up and found a blown fuse! Whiskey tango foxtrot! Fortunately, there was a spare unit tucked away inside the battery compartment.

§

There's maybe a lesson to be learned here: do not do early prototype testing with expensive dew straps...