Connections to the Board
- Published: Wednesday, 10 April 2013 22:43
- Hits: 35226
The following picture shows the different external connections to the board. You can screw or solder on the antennas.
There is an standard audio and USB connector. A pad to solder on an extra ground wire.
And then there is the Arduino ISP programming connector accessible through the shield
(you will only need this to directly program the arduino chip, usually you will go through the USB connector with the arduino IDE).
-> Get your board now in the Small Batch Store.
Notes on setting up and using the Open.Theremin.UNO
You can use any electrically conductive material. I use aluminium rods. Just stiff wire works well to. The total length per antenna should be around 40 to 50 cm. If you use longer antennas you would have to adjust the tank capacity to compensate.
Means to ground the theremin.
Use any of the following methods to ground your theremin.
1. Use a grounded audio cable. If you connect your theremin to a mixer or amplifier that is grounded, the theremin is grounded through the audio cable.
2. Use a grounded power supply. You can power your theremin through the USB plug (by a device like a computer or a power adapter with USB connector) or by a separate power adapter. If the power supply is grounded the theremin is grounded as well. Notice that many USB power adapter and power supplies are not grounded.
3. Use a separate grounding wire. There are soldering pads on the open.theremin.Uno board where you can connect a extra grounding wire. Attach this wire to a grounded metallic object in your room (like a lamp or a water tube)
In theremin all is about capacities. The theremin measures smallest variations of capacities (less than 1 pico Farad). The capacity between the antenna (it is in this case actually an electrode) and your hand is measured and translated into the pitch (or the volume) of the sound. So in fact you with your whole body are part of the electronic instrument. The electric loop with the instrument is closed from your hand through your body, through your shoes through the floor into the ground and from ground back into the instrument. This is why proper grounding of the instrument is important. And not only your body is interfering with instrument, also a table or an object close to the theremin will add to the capacity sensed by the instrument. So best is to put up the theremin on a stand in the open space. You might ask how can the current go through my shoes if they are isolated. Again, it is all about capacity. And your shoes form again a capacity with the floor, even if an isolation (or often dielectric material) is in between. For high frequencies a capacity acts like a short circuit. It is isolating only for DC current. This again is why a bird or even a fly could (theoretically) play theremin. With its presence it influences the field in the capacity between the antenna and the ground even when not touching either of them.