# Uses of various components in electrical systems

1. Feb 22, 2009

### Riddles

1. The problem statement, all variables and given/known data
To state the uses of Capacitors, Resistors and Diodes in

Laptop computers, Midi sound systems and Ipods

2. Relevant equations

3. The attempt at a solution
I've looked around on the internet and tried a good few books but I can't find the specific information. I've been looking up the various types of each but I can't determine which one is whih. Electricity isn't exactly my strongest subject.

2. Feb 22, 2009

### Delphi51

Here's a start:
Capacitors smooth out ripples in DC power - in all the devices mentioned.
Voltage dividers made of resistors provide the necessary operating voltages for transistors.
Diodes convert AC to DC and prevent damage from putting the batteries in backwards.

3. Feb 23, 2009

### Riddles

Ah thank you.

but when you say 'smooth out', how do you mean?

4. Feb 23, 2009

### rock.freak667

Diodes convert an AC to a varying DC, which isn't too useful. So capactors are added which helps to convert a varying DC to a more or less steady DC

5. Feb 23, 2009

### mgb_phys

Perhaps a simpler example - diodes only let electricity flow one way.
How would this be important in say charging an iPod?

Variable resistors change the level of a signal - when would you need to do this on an iPod?

6. Feb 23, 2009

### Delphi51

When AC is converted to DC to run electronic devices, there is 60 Hz powerline ripple in the DC which would cause 60 Hz hum in any audio device and all sorts of trouble in a logic circuit. A capacitor from the DC + to DC - will store voltage in the highs and release it in the lows tending to average out the voltage to a steady value, eliminating the hum.

Interference from radio transmissions, lightning, welding, people switch motors on and off will cause high frequency transients on the device. Capacitors are like short circuits to these high freqs, so they are eliminated, too.

7. Feb 23, 2009

### Riddles

Ah I see now. Thanks!

So the diode would prevent the electricity from flowing from the ipod to the charger?

And the resistors are used in the volume by letting out set amounts of current through?

8. Feb 23, 2009

### Delphi51

Probably not needed for that, since the charging V will be higher than the V of the batteries. I was thinking of preventing damage to the circuit when operating on batteries, when the batteries have been put in backwards, with reverse polarity. A diode would prevent current from flowing backwards which could damage the circuit. This is a 5 cent solution to what would otherwise be a big problem.

And the resistors are used in the volume by letting out set amounts of current through?
Yes, a volume control is basically a variable resistor that selects part of the signal - usually potential rather than current.

9. Feb 23, 2009

### Riddles

Ah right.

You've all been a great help!

Thanks!