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Have you ever needed a variable AC Power Source to test out DIY projects? Or do you need a variable frequency source to drive a turntable having a hysteresis synchronous or shaded pole induction motor to produce various RPM values? Well, here is a very easy way to create a 100 Watt Variable Voltage, Variable Frequency power source. Along with the schematic in .doc format located at the bottom of this post, all that you will need is:
1. An old 75 Watt / Channel (or greater) Stereo Receiver or Integrated Amplifier
2. Your computer with Sound Card
3. A copy of Diamond Cut Software having the "Make Waves" Generator.
4. Two Radio Shack Model 273-1512 / 25.2 Volt, 2 Amp power transformers (or equivalent)
5. Four Slow Blow Fuses per the attached schematic
6. Two or Three Electrical Outlets depending on requirements
7. A little time to put it together
The performance of this system will be as follows:
Output Power and Voltage: 2 x 50 Watts @ 120 VAC or 1 x 100 Watts @ 240 VAC
Output Voltage Range: 0 to 127 VAC
Output Voltage Frequency Range: 47 to 400 Hz
----------------------------------------------------
Approach:
Download the schematic in .doc format. You will first need to construct this circuit which should take about 2 or 3 hours. As an overview, your soundcard connects to the Aux inputs of your old receiver. Both the left and right channels are used and connected to the soundcard. The outputs of the receiver are connected to the 25.2 Volt secondary of the mentioned power transformers via fuses. The primary (120 VAC) windings of the transformers are connected to three electrical outlets via fuses. Two outlets are simplex 120 VAC 5-15 P types. The remaining one is a 240 VAC type, which is optional depending on whether or not you need that value of Voltage.
The Diamond Cut software Make Waves Generator is set up to produce Sine Waves with the following parameters:
1. Frequency: 47 to 400 Hz
2. Waveshape: Sine
3. Resolution: 16 bits
4. Mode: Stereo
5. Sampling Rate: 44.1 KHz
6. Amplitude: -2 dB
7. Time: 600 Seconds
Before "playing" the wavefile, turn the volume control all the way down on the amplifier. Run the software and, using a Voltmeter connected into one of the outlets, slowly increase the Volume Control until the desired Voltage is obtained. If the 240 VAC outlet reads 0 while both 120 VAC read correctly, then you will need to reverse one pair of leads on one of the transformer primaries (120 VAC Side) or run a file conversion filter with one channel set for "inverted".
Note: Another interesting application for this is use as an electrical timer. By selecting the desired length of the "Make Waves" file, you can precisely establish a certain time interval. The output of the system can drive some items directly, and larger items via a power relay. It can be used to drive photo enlargers or any illuminator used in photosensitive processes such as silk-screening. I am presently using this system as a timer to establish a determinate exposure time of certain pathogens to anti-pathogenic (toxic) agents as part of a research project that I have been hired onto.
keywords: Power Source, AC Source, Timer, Synchronous Motor Drive, Variable Timer, AC Power Supply, variable turntable speed, varying turntable speed
1. An old 75 Watt / Channel (or greater) Stereo Receiver or Integrated Amplifier
2. Your computer with Sound Card
3. A copy of Diamond Cut Software having the "Make Waves" Generator.
4. Two Radio Shack Model 273-1512 / 25.2 Volt, 2 Amp power transformers (or equivalent)
5. Four Slow Blow Fuses per the attached schematic
6. Two or Three Electrical Outlets depending on requirements
7. A little time to put it together
The performance of this system will be as follows:
Output Power and Voltage: 2 x 50 Watts @ 120 VAC or 1 x 100 Watts @ 240 VAC
Output Voltage Range: 0 to 127 VAC
Output Voltage Frequency Range: 47 to 400 Hz
----------------------------------------------------
Approach:
Download the schematic in .doc format. You will first need to construct this circuit which should take about 2 or 3 hours. As an overview, your soundcard connects to the Aux inputs of your old receiver. Both the left and right channels are used and connected to the soundcard. The outputs of the receiver are connected to the 25.2 Volt secondary of the mentioned power transformers via fuses. The primary (120 VAC) windings of the transformers are connected to three electrical outlets via fuses. Two outlets are simplex 120 VAC 5-15 P types. The remaining one is a 240 VAC type, which is optional depending on whether or not you need that value of Voltage.
The Diamond Cut software Make Waves Generator is set up to produce Sine Waves with the following parameters:
1. Frequency: 47 to 400 Hz
2. Waveshape: Sine
3. Resolution: 16 bits
4. Mode: Stereo
5. Sampling Rate: 44.1 KHz
6. Amplitude: -2 dB
7. Time: 600 Seconds
Before "playing" the wavefile, turn the volume control all the way down on the amplifier. Run the software and, using a Voltmeter connected into one of the outlets, slowly increase the Volume Control until the desired Voltage is obtained. If the 240 VAC outlet reads 0 while both 120 VAC read correctly, then you will need to reverse one pair of leads on one of the transformer primaries (120 VAC Side) or run a file conversion filter with one channel set for "inverted".
Note: Another interesting application for this is use as an electrical timer. By selecting the desired length of the "Make Waves" file, you can precisely establish a certain time interval. The output of the system can drive some items directly, and larger items via a power relay. It can be used to drive photo enlargers or any illuminator used in photosensitive processes such as silk-screening. I am presently using this system as a timer to establish a determinate exposure time of certain pathogens to anti-pathogenic (toxic) agents as part of a research project that I have been hired onto.
keywords: Power Source, AC Source, Timer, Synchronous Motor Drive, Variable Timer, AC Power Supply, variable turntable speed, varying turntable speed