Running Theremin

I recently got the E-Standard and I LOVE it! Will leaving it turned on for extended periods of time (days) harm it? What about other Theremins?

In the short term...no. In the long term....yes.
All electronic componenets have a limited lifetime. Leaving them powered up needlessly for hours and days at a time will shorten the unit's usable lifetime. The most susceptable parts will be the power supply, electrolytic capacitors, and any component that is marginally functional.

That makes sense, thanks! There's this local Electricity museum that has a working 1929 Theremin that visitors can play. I wonder how much of it is still original, and how many times the rest has had to be repaired/replaced.

With carbon footprints being mentioned wherever one looks, be kind to our planet!. I have been guilty over the years of leaving both valve and transistor Hi Fi equipment on for long(very)periods of time. There is a balance of the initial shock to a component when turning on the power that can do more harm than leaving things on
for extended periods. But I'll say again mind my planet.

Carport, where is this museum? I may juts have to engineer a little trip fr my family and me.

I will have to come up with some other reason for the trip see and just happen to spot the museum...

Why the hell would you leave it on for that long? I'd say unless it was necessary (like, if it were part of an installation or something) you should avoid leaving it on unless you intend to play it.

Charlie D - I wouldn't leave it on for that long intentionally, but knowing the importance definately encourages me to remember to turn it off! I'm usually good about it anyway.

DiggyDog - It's at The American Museum of Radio and Electricity (http://www.amre.us/site/exhibits.html) in Bellingham, Washington. It's about 3 hours away from me. I may have to make the trek up there myself. Serial No. 200085 (http://www.thereminworld.com/RCARegistry.asp).