Attempting to figure out a way to have the computer control the volume of an audio amplifier:

• Reference for electronic diagram symbols:  http://library.thinkquest.org/10784/circuit_symbols.html
• Reference for how to use a multi-tester: http://www.wikihow.com/Use-a-Multimeter
• The amplifier potentiometer gives the best volumes between  992- 950 ohms.
• To measure current, the multi-tester needs to be in series with the circuit.  I am removing the potentiometer from the amplifier circuit so I can put the multi tester in series after it and read the range of current.  How many amps the current is will determine if I need to use a jfet or mosfet transistor for the voltage controlled resistor.

After taking off the potentiometer, we realised that this may not be the best way to have our speakers volume controlled.  We are looking into a couple of different IC amplifiers with programmable gain control.  See tomorrows entry for more details on this.

Other uses for capacitors besides storing energy to be released in burst or dimming lights.

• Timing – for example with a 555 timer IC controlling the charging and discharging.
• Smoothing – for example in a power supply.
• Coupling – for example between stages of an audio system and to connect a loudspeaker.
• Filtering – for example in the tone control of an audio system.
• Tuning – for example in a radio system.