Or are they night-terrors? I haven’t been able to get the tube amp in a mint tin idea out of my head. Assuming a suitable sub-mini tube type exists, the first obstacle is generating a B+ (48V or more) from battery power. For that, a DC boost circuit is in order. Of course, you should also have an easy way to recharge because whatever you build will probably eat batteries with complete abandon.
Here’s something untested and completely silly on the topic:
wauwatosa tube factory 
I found an antique Altoids tin roughly 5-6” x 6-8” x ~ 1.25”…can fit more in that…
But I’ve never found another. Maybe they are unpopular gifts…people might assume such a gift implies a serious need for breath mints.
Then there’s the tiny Dog Breath Mints tin my daughter gave me…she knows my sense of humor.
Hey, your universal power transformer article helped me sell some transformers on eBay…buck, boost, FWB & FWD configurations with pics showing ac input on DMM & unloaded DC output on DMM…
Murray
On Wednesday, April 11, 2018, wauwatosa tube factory wrote:
> Timothy Cose posted: “Or are they night-terrors? I haven’t been able to > get the tube amp in a mint tin idea out of my head. Assuming a suitable > sub-mini tube type exists, the first obstacle is generating a B+ (48V or > more) from battery power. For that, a DC boost circuit is i” >
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