Melodia battery?

Hello,

I recently came into a 1961 Melodia theremin. Supposedly it runs on batteries. Does anyone have any idea where to find one so I can get this thing running and making some music again? I thought I found a scematic that said it needed a 6 volt (eveready 724 or equiv) Any 6 volt battery I can find now is horrible not the correct size. I even took the thing into the batteries plus store and they had no idea what to put in there. Has anyone ever changed a battery for this particular theremin or rewired it for a different kind of battery or made an adaptor, etc? I would greatly appreciate any help.

Hello exarctly,

6 volts is 6 volts so if you're in the states use one of Radio Shacks 4 cell AA battery holders. You have a nice collectable but you will want more if you become serious about the theremin. Also your theremin will need the negative side of the power supply connected to a good earth ground to behave properly.

RS Battery Holder       Eveready 724 Photo & Info

Edit: The earth ground issue is solved if you plug into an amplifier that uses a three prong earth ground wall plug.

Christopher

Seems as though finding the actual eveready 724 is tough to find... so you are saying I can use four double A batteries with one of these holders, make sure it is properly grounded and I should be good to go. You are saying the 4 cell AA holder should be large enought to fit in there? Thanks for your help. I will give it a shot, so long as you think I won't fry anything if the AAs aren't a little more or less than 1.5 volt each. I have heard that these theremins are collectables because they are old and rare, but also that at the time they were kind of more low key beginner theremins. So I am entertaining the idea of selling or trading it for another theremin plus a cash difference. Though part of me wants to keep it because it is so neat and will probably only go up in value anyway. Bottom line is, one way or another I will play the theremin. 

Make sure you get the polarity right when the holder is wired in. Reversed polarity can burn out components.

Hmmm. How would I know what the correct polarity is, and how to set it correctly?

Christopher... I do not see how I can plug this thing in to an amplifier? Unless I get an adapter. The cable that goes out of it is sort of more of an RCA looking...well, I don;t even know what, but it is not an instrument jack, my thought was to stick it ito a PA which seemed to have the correct size. Unless like I said, I buy something that converts it to the correct size for an amp.

Use an adapter. I use cables with RCA plugs on both ends all the time because they make good contact, use along with a mono 1/4" plug that has the RCA female adapter on the other end. I do not have a Melodia but viewing its schematic it is straight forward. Momentary polarity reversal should not cause any harm. The amp should accept a line level at the input like a keyboard or PA amp.

Melodia Schematic

Thanks for all your help. So, you are saying... use an adaptor for plugging the thing in to an amplifier, but use a the 4 AA cell battery holder to get power. Well, I will try in the next week and let you know how it goes. Thanks again! 

Plus side is wired to the switch, minus side is wired to ground. On the existing battery connector the wire going to the on/off/standby switch is plus. The other wire is negative. On the battery holder the plus wire is probably red. The negative should be a black wire.