We have self-constructed a logic probe using:
1x Red L.E.D
1xGREEN L.E.D
1x Black wire(2 meters in length)
1x Red wire(2 meters in length)
2x 1K resistors
1x Red alligator clip
1x Black alligator clip
1x 100mm plastic 7mm diameter
Shrink tubing
1x Black 2.4mm diameter 300mm long
1x Red 6.4mm diameter 175mm long
1x Black 12.7mm diameter 125mm long
1x Brass rod 150mm long
Construction:
1st we soldered the 1K resistors and wires together then we soldered the L.E.D's to the resistors of the positive and earth wires respectively.
Next we put the heat shrink over both the wires up to the L.E.D's and proceeded to use the heat gun to shrink the material around the wires.
Next we have to solder the L.E.D's to the brass rod, then we machine the end of the brass rod to a pen like tip.
After that we put heat shrinks over both ends of the brass rod leaving the pen like tip exposed and L.E.D's visible and apply the heat gun.
next we cut a groove out of the plastoc tube approx 5-10mm long and then we put the plastic tube over both wires and position it just behind the L.E.D's then put a large heat shrink over the plastic tube and then apply the heat gun proceed to do the same to the other end still leaving the pen like tip exposed.
Next we solder the alligator clips to the respective wires for positive and earth wires.
To Test:
Attach to a power supply no more than 24v DC
Then touch against positive and negative terminal, the red L.E.D should light up on the positive terminal and the green L.E.D should light up on the earth wire.
The Logic Probe uses a series circuit with 2 one way diodes one allowing flow to the positive and the other allowing flow to the earth
Thursday, March 31, 2011
Sunday, March 20, 2011
Alternators
OFF CAR ALTERNATOR EXERCISE
In this exercise we disasembled a alternator that was off a toyota camry. We then performed tests on the various components of the alternator, the first test was to check if there was a circuit through the slip ring this was done using a digital multimeter the result of the reading was infinity. The next test was to find the internal resistance this was done using a multimeter the specifications for results was anywhere between 2-6 Ohms we got a reading of 2.8 Ohms on our slipring our tests conclude that the slip ring is operating correctly.
The next component tested in the alternator is the stator, the stator is measured from the common(the point which has the most wires connected) the stator was tested for resistance
from point A to D the resistance was 0.2 Ohms which is within the specification range of 0 Ohms to 0.2 Ohms from point A to C the resistance was 0.1 Ohms also within the specification range
from point A to B the resistance was 0.0 Ohms
the final test on the stator was from the common to the earth to test for a circuit the result was an infinity reading meaning there is no circuit.
The stator's purpose is to act as the conducter in the alternator when the car is running .
The next component tested was the rectifier, it was tested for voltage drop on the positive diode first
the specifications where between 0.5-0.7VD
at point 1 the reading was 0.512VD
at point 2 the reading was 0.486VD
at point 3 the reading was 0.500VD
on this test point 2 failed to meet the specifications.
The next test was a positive diode test, all 4 points measured as infinity which was the specifications.
The negative diode test with the negative lead on earth measured as infinity which was the specification as seen below:
The next test was the voltage drop for the negative diode
at point 1 the reading was 0.518VD
at point 2 the reading was 0.513VD
at point 3 the reading was 0.527VD
on this test there where no points that failed.
The purpose of the rectifier is to turn alternating current to direct current for the motor vehicle
The next test was a transpo-regulator test which is desinged to test an alternators regulator.
The spec's for our test are:
part number: IN225
field setting: A
voltage: 12v
set point spec: 14.5v
in the test the short circuit light was off, the warning light was on and stayed on and the field light was flashing continuously the setpoint voltage read as 14.5 which was a pass result.
the purpose of the voltage regulator is to keep the voltage at the required level for the load on the alternator and to stop it producing voltage when it is not needed.
The last test was done on the alternator brushes testing there length both brushes measured at 7.5mm each the specification are at 4mm each so a pass resuly, the point of the brushes is to supplly electricity to the slip rings
ON CAR ALTERNATOR TESTING
In this exercise we performed various tests on an alternator that was still attached to the vehicle,
the first thing we did was a check for saftey things such as is the vehicle in park/neutral?, is the hand break applied?, etc apon checking the engine and charging system i recorded that the mazda 323 engine that i was using is chain driven, the teeth all have good length on them the chain is properly tensioned and runs across the alternator correctly. We then carried out a "no load" test the OCV was measured at 12.6v the regulator volt spec was 14.5v and the regulator voltage reading was 13.8v, the "no load" ampere output was 9.6 amperes which is withing the specification range for a carburetted engine of between 5 to 12 ampere's.
In the "load" test we used a induction multimeter, we started buy adjusting the RPM to 2,500 we then put a load on the alternator the ampere reading we got was 21.9 ampere's and the charge voltage under load was 12v which was a failed test this is most likely due to the engine having old and tired components.
We performed a voltage drop test on the engine.
The first point was between the battery positive and alternator output while the engine was running, giving a result of 0.13VD the specifications here was a volt drop below 0.20VD.
The second point was between the battery negative and the alternator body while the engine was running, giving a result of 0.16VD the specifications here where also a volt drop below 0.20VD.
the total voltage drop across the engine was 0.29VD the specification was for a total voltage drop below 0.40VD
Overall the engine proved to be in an electrically well kept state
In this exercise we disasembled a alternator that was off a toyota camry. We then performed tests on the various components of the alternator, the first test was to check if there was a circuit through the slip ring this was done using a digital multimeter the result of the reading was infinity. The next test was to find the internal resistance this was done using a multimeter the specifications for results was anywhere between 2-6 Ohms we got a reading of 2.8 Ohms on our slipring our tests conclude that the slip ring is operating correctly.
The next component tested in the alternator is the stator, the stator is measured from the common(the point which has the most wires connected) the stator was tested for resistance
from point A to B the resistance was 0.0 Ohms
the final test on the stator was from the common to the earth to test for a circuit the result was an infinity reading meaning there is no circuit.
The stator's purpose is to act as the conducter in the alternator when the car is running .
The next component tested was the rectifier, it was tested for voltage drop on the positive diode first
the specifications where between 0.5-0.7VD
at point 1 the reading was 0.512VD
at point 2 the reading was 0.486VD
at point 3 the reading was 0.500VD
on this test point 2 failed to meet the specifications.
The next test was a positive diode test, all 4 points measured as infinity which was the specifications.
The negative diode test with the negative lead on earth measured as infinity which was the specification as seen below:
The next test was the voltage drop for the negative diode
at point 1 the reading was 0.518VD
at point 2 the reading was 0.513VD
at point 3 the reading was 0.527VD
on this test there where no points that failed.
The purpose of the rectifier is to turn alternating current to direct current for the motor vehicle
The next test was a transpo-regulator test which is desinged to test an alternators regulator.
The spec's for our test are:
part number: IN225
field setting: A
voltage: 12v
set point spec: 14.5v
in the test the short circuit light was off, the warning light was on and stayed on and the field light was flashing continuously the setpoint voltage read as 14.5 which was a pass result.
The last test was done on the alternator brushes testing there length both brushes measured at 7.5mm each the specification are at 4mm each so a pass resuly, the point of the brushes is to supplly electricity to the slip rings
ON CAR ALTERNATOR TESTING
In this exercise we performed various tests on an alternator that was still attached to the vehicle,
the first thing we did was a check for saftey things such as is the vehicle in park/neutral?, is the hand break applied?, etc apon checking the engine and charging system i recorded that the mazda 323 engine that i was using is chain driven, the teeth all have good length on them the chain is properly tensioned and runs across the alternator correctly. We then carried out a "no load" test the OCV was measured at 12.6v the regulator volt spec was 14.5v and the regulator voltage reading was 13.8v, the "no load" ampere output was 9.6 amperes which is withing the specification range for a carburetted engine of between 5 to 12 ampere's.
In the "load" test we used a induction multimeter, we started buy adjusting the RPM to 2,500 we then put a load on the alternator the ampere reading we got was 21.9 ampere's and the charge voltage under load was 12v which was a failed test this is most likely due to the engine having old and tired components.
We performed a voltage drop test on the engine.
The first point was between the battery positive and alternator output while the engine was running, giving a result of 0.13VD the specifications here was a volt drop below 0.20VD.
The second point was between the battery negative and the alternator body while the engine was running, giving a result of 0.16VD the specifications here where also a volt drop below 0.20VD.
the total voltage drop across the engine was 0.29VD the specification was for a total voltage drop below 0.40VD
Overall the engine proved to be in an electrically well kept state
Monday, March 14, 2011
Saftey
Personal protection equipment is the equipment that each individual uses to protect themselves from any possible accident or injury that may occur to themself, this equipmen includes things such as overalls, steelcap boots, saftey glasses and gloves. In auto-electrical work the biggest danger is electricution, this can be avoided by making sure that the ignition is off when doing electrical work on it and also making sure that all mains for power are correctly earthed and contain a circuit breaker.
Sunday, March 13, 2011
Circuits
There are three types of circuits; circuits in series, circuits in parallel and combined circuits.
Series and parallel circuits respectively are known as individual circuits, where as a combined circuit is one in which there are one or multiple series and parallel components to the circuit as a whole.
We can see that the three bulbs are brighter than the bulbs in series this is because the bulbs are each drawing the maximum availible voltage from the supply although they are still limited by there individual wattage of the bulbs, in a parallel circuit the components draw a consistant amount of current which is higher than that of the series circuit due to less resistance.
In a combined circuit we have series and parallel components to the whole circuit respectively.Of note in the combined circuit when calculations are needed you are to work out the total resistance of the parallel component of the circuit first. with ths kind of circuit there is a share of voltage between the components of the combined circuit, in this type of circuit if we have a twelve volt circuit with two bulbs in parallel and three more bulbs in series in the whole circuit the bulbs in parallel will use the maximum availible voltage each and the bulbs in series will share the remaining volts between them. An example of this is the double filiment bulbs in brake lights where when driving at night if one of the filiments blows the other will still be lit when the headlights are on but will go out when the brake pedal is applied.
Series and parallel circuits respectively are known as individual circuits, where as a combined circuit is one in which there are one or multiple series and parallel components to the circuit as a whole.
In a series circuit that has a twelve volt supply the components are all runing off the one voltage so as the current flows through the circuit and across the components the voltage of the components drop for example if you have two light bulbs in a series circuit such as this one:
The light bulbs or components both use six of the twelve volts availible to the total circuit, this is because there is less current due to more resistance in the circuit. When compared to a single bulb in series causes the two bulbs in this circuit to be dimmer.
In a parallel circuit that has a twelve volt supply the components are using the whole twelve volts each so when we look at this three bulb circuit wired in parallel:
In a combined circuit we have series and parallel components to the whole circuit respectively.Of note in the combined circuit when calculations are needed you are to work out the total resistance of the parallel component of the circuit first. with ths kind of circuit there is a share of voltage between the components of the combined circuit, in this type of circuit if we have a twelve volt circuit with two bulbs in parallel and three more bulbs in series in the whole circuit the bulbs in parallel will use the maximum availible voltage each and the bulbs in series will share the remaining volts between them. An example of this is the double filiment bulbs in brake lights where when driving at night if one of the filiments blows the other will still be lit when the headlights are on but will go out when the brake pedal is applied.
Subscribe to:
Posts (Atom)