Timing resistor - Capacitor circuits with voltmeters

TTEC 4841 - Electrical and Electronics- Practical

26/8/2011 tuesday

start = 1.00pm finsh = 4.30pm

In todays task we learned about timing resistor - capacitor circuits using a voltmeter.

First thing we did was to idintify the electroytic capacitor the Black side is the negative and the white side it the positive.

Then we moved on by writing what is a capacitor.? capacitors are used to store eletric change and prevent voltage spikes. the negative plate area provides a form of reservair into which electrons can flow and this stores any excess of voltage.

Then we moved on by calculating how fast the capacitor should charge using the formula =( R*C*5*T )

capacitance ( uF )	capacitance ( F )	*	resistance ( ohms )	*	5	calculated time ( second )
10	0.00001	*	1,000	*	5	0.05
1	0.000001	*	250,000	*	5	1.25
100	0.0000001	*	10,000	*	5	5
300	0.0003	*	4,5000	*	5	6.75

Then we did evaluate the charge Time

capacitance	yes	no
10 uF		no
1 uF		no
100 uF	yes
300 f	yes

 Then we calculated resistor size , we got given servel capacitors of different sizes.

	capacitance ( uF )	capacitance ( F )	*	5	=	Answers ( A )
1	330	0.00033	*	5	=	0.00165
2	100	0.0001	*	5	=	0.0005
3	0.47	0.00000047	*	5	=	0.00000235
4	10 micro	0.00001	*	5	=	0.00005

Then we divided 180 ( seconds ) by the answers A to calculate what size ressitor will be needed to have the capacitor charge in about 3 minutes

	calculated time ( seconds )	/ by	Answer (A)	=	Resistance in ( ohms )
1	180	/	0.00165	=	109090.91
2	180	/	0.0005	=	360,000
3	180	/	0.00000235	=	765,957,45
4	180	/	0.00005	=	3600,000

Then we moved on doing By building a capacitor charging circuit using the following things

Components

• 1 * resistor
• 1 * capacitor
• 1 * bridging wire
• 1 * voltage source ( battery or power supply )

Then we moved on by monitoring the capacitor charge with a time verse voltage.

Then we moved the bridge wire and recoreded the voltage every 5 second for 3 minutes approximately.

which that gave us a graph of plot the capacitor charge up time on the graph.

over all this showed us that the voltage started low then it build its way up.

 with our graph our resistor over charged and stopped at a surten spot which was 8.29 so it was hard to get volts in. if theres more capacity its easy to get volts in there as its fully charged if theres less capacity its hard to charge. so its start going higher where it it stopped at a surten place which was 8.29