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Current state... after issues with new Theremin like capacitive sensors picking up static electricity from Monitor, i had to revert back to foil, and think of a better form of sensor housing... Thus the circuit is not yet soldered and housing not yet placed back on CRT.

Both Electromagnets are fixed within the CRT and both signals pass from the arduino through them and alternating frequencies. however due to a change in sensors at the last minute , the code was not performing correctly and needs some readjustment.

Demo of final project, (preliminary).

What needs to be finalised:

- Housing

- capacitive sensor objects?

- image content

- microphone

- circuit soldering

#documentation

Clip taken from one of many experiments in where to place the electromagnet. This time it was placed under the cathode ray tube, nice subtle effect.

#documentation

First test using the first capacitive sensor with the electromagnet + CRT.

#documentation

Testing a range of wave signals from the arduino, and sampled wave tones from the internet for comparison through a homemade oscilloscope.... (sadly this CRT came to an unfortunate end early on in the project and so will forever only be an oscilloscope).

#documentation #oscilloscope

Wires snapped on first electromagnet, so second one was made.

After experimenting to find the best location for the magnet it was installed in the back of the CRT using hot glue.

Also had to change the design of the original circuit so as to free up some pins, (as for the capcitive sensors I would need pins 2, 4 and 5). This was done using a 1-bit DAC instead of the R2R ladder and some alterations to the code, resulting in only pin9 needed for PWM output.

#documentation #electromagnet

::Audio out circuit::

Testing with oscilloscope...no longer getting a perfect sine wave, puzzled. Tried replacing odd resistor in R2R ladder and checking over circuit on breadboard along with the code but all seemed correct.

#documentation

::ElectroMagnet Test::

Testing the effectiveness of the Electromagnet on the CRT Monitor. Square wave sent from arduino , passed through an R2R ladder, Low Pass Filter and Op Amps to change the signal to a sine wave. This is then passed through the electromagnet which is placed near the Cathode Ray Tube. (Image present on the monitor is a Jpeg from a media player).

#documentation #electromagnet #crt tv

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Nice use of capacitive sensors…

#research #capacitive sensors

::Testing the Electromagnet::

9V battery.

// later discovered that I should not have used LED’s as something to pick up with electromagnet as they are polorised and so will short out hardware.

#log #electromagnet

::Making The Electromagnet::

- Enamelled copper wire

- Electrical tape

- Steal rod

- Much patience

Resitance = 9.1 Ohms

#log #electromagnet

::First stage , breadboard diagram and schematic::

Arduino Output :

PWM Square Wave

Circuit Output:

Sine Wave with potential controlled applitude, to Mono Jack for audio output, which will be passed through the electromagnet.

#log #schematic #fritzing

::TL072 Dual Op Amp::

1. Use 2 of these to increase the current of the signal so that it can drive a load (like a speaker). Both op amps on one TL072 package as parallel voltage followers. What this means is I sent the output from the amplitude pot to the non-inverting input of both op amps. Then I wired both op amps as voltage followers and connected their outputs to each other. Since each op amp can source 80mA of current, combined they can source 160mA of current.

2. Op Amp installation Schematic.

#op amp #log

Using the electromagnet ...

The electromagnet needs to be between 4-8 Ohms this is around the same resistance of an audio speaker (or impedance when your talking about an alternating current signal like audio).

My electromagnet is 9 Ohms.

If I amplify an audio signal, such as a sine wave (from the arduino), and replace the speaker with the magnet, I will have a magnet that is rapidly switching polarity. This is more effective than a stationary magnet as I'll be able to make an image wobble over time rather than just a still distortion.

#log #electromagnet

R2R ladder oscilloscope test and code test.

result: sine wave!

#test #r2r ladder #oscilloscope #arduino

R2R Ladder test.

#test #r2r ladder #arduino

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