Compound circuits

Not much was done with the Compound circuits as it was a combination of parallel and series and since weve already learnt about those, it was pretty self explanitary on what was going to happen with this circuit.

This image was sourced from google. (this image apparantly came off someone else's blog)

 

The parallel part of the circuit would keep the current of the parallel bulbs operating at a equal brightness while the series part of the circuit would have the bulb operating at little to no voltage drop but will consume all of the available voltage.

parallel circuits

A parallel circuit is a very power efficient type of circuit.
All consumers will take all the available voltage equally if connected in a parallel circuit.

The circuit has the same componants as any other circuit (powersource, bulbs, wiring etc), but instead of being connected in series (one after the other) the componants (or bulbs in this case) are connected in parallel (hence parallel circuit). Here is a picture to show you what i mean by connected in parallel.

If the bulbs are connected in parallel they will have the same voltage across all ends as the current will comeback together in the end.

The Parallel circuit was assembled and put to the test.
The switch on the circuit was turned on and the result was that all 3 bulbs glowed with the same brightness.
Rather than in a series circuit were each bulb would get dimmer 1 after the other, the parallel circuit however will have all bulbs glowing with the same brightness (as said before).

relays

Ahh Relays...the hardest of all the circuit componants...well i thought it was.

A relay could be thought of as a magnetic switch, were a low amp circuit to switch on a higher amp circuit.
The Relay will have a coil of wire inside that will create a magnetic field when the circuit has power.
The second circuit in the relay will be a switch that when the first circuit is on, the magnetism will pull the switch in the second circuit on, completing the relay and turning on whatever component it is connected to.

We learned how these worked by testing them on lights.
We made up a circuit that involved the Relay component, then added bulbs to the circuit.
Turning in one switch on the circuit made the 2 out of 3 bulbs glow and the second switch on the circuit made all three glow brightly...the relay was working.

Diodes

Diodes were an interesting type of circuit componant.

I already knew a bit about them which helped me a bit through the subject.

Diodes are an electrical componant that stops power surges or just basic current flow from flowing back from its source.
Diodes only allow current flow go one way and this prevents surges stopping any electrical device to short out from Backflow.

Thats basically all i can say about Diodes as thats all they do.

The way I learnt this about Diodes this time was that the class told to make a Logic probe.

We had 2 LED's (light emitting diodes) Some wires, some heat-shrink, a brass rod, 2 resistors, 2 alligator clips and a plastic tube for insulation.

we soldered the LED's on the wires, one wire per LED and insulated some contacts on the brass rod with heat shrink the resistors were soldered onto the wires and the wires were soldered onto the brass rod. the alligator clips were attached to the other ends of the wires and then we were done. (A brief explanation on the build but you get the jist of it)

we tested the Logic probes on powered volt meters to see if they worked, thus they did, when theres a positive power source the logic probe lights up green and negative lights red.

Series Circuit

My next lesson was learning about a series circuit and how its worked.

The series circuit is very similar and almost identical to the individual circuit but involves attaching 2 or more bulbs onto the circuit.

The components needed are the same as that of the individual circuit (bulb/s, switch, fuse, power supply and nessesary wiring).

A series circuit works the same way as a individual circuit but with added bulbs or consumers.
The bulbs/consumers act as a resistor and consume the voltage as it goes through the circuit soaking up power from consumer to consumer but as it travels through the bulbs (for example) each one, one after the other will get from the resulting voltage drop.

Starter motors

We started off by our normal safety procedure, overalls etc.
we needed our tools, mainly screwdrivers and sockets, then we got started.

We were given a starter motor and was told to find a problem (later revealed it had no problem, but to teach us how to find out it didnt).it was tested on a test bench where the operator made it look like it had a problem so then we could investigate.

We started by taking the starter completly apart so then we could test and examine all the individual parts.
from solenoid to commemtator and brush plate, etc.
to disassemble we removed the M terminal wire from the solenoid, removed screws from the commutator housing, removed the commutator housing, removed the brushes aswell as the brush plate, removed the armature, etc.

First was the visual inspection on the armature, there was no overheating, no burning, no physical damage and a little it of poling...by little i mean tiny suface scratches.

next test was ground testing the windings with a multi meter, the reading must read (infinity) as there is no circuit between the winding and the ground, if there is a connection to earth, the winding needs to be replaced or re-wound.

next test, continuity circuit test.
using the multi meter set to ohms, check each commutator segment with 1 probe on 1 segment and dragging the other probe around the rest of the segments. test result was 0.0001Ohms - serviceable.

next test, measuring commutator diameter.
taking a vernier caliper to measure, we measured the diameter of the commutator, result: 31mm.
26.8-31mm being the manufacturer'a specs.

next test, the growler test
placing the armature onto the growler machine and rotating the armature 360degrees whilst lightly balancing  a hacksaw blade upon the top. If the hacksaw blade starts to chatter along the armature during rotation on the growler, there is a short circuit along the armature segments. Result: no chatter-serviceable

next the brushes were examined.
The brushes was measured and were at a serviceable length.
a quick visual examination shows they were also in good condition.

next the solenoid magnetic switch was tested.
Terminals: B-battery power, S-ignition/starter switch supply and M-Starter motor supply.
A 9V power supply was hooked up to its terminals, it drew a current of 25Amps and the solenoid plunger pulled in...operated as it should.

after a long session of testing, i come to the last test of the starter, checking the pinion gear and clutch.
the pinion gear has little to no wear and tear, the bushes are in good condition and has little "play" and the one-way clutch operates as it should.

Q and A

1.To turn the engine enabling it to start.

2. 1-Armature
    2-Field coils and pole shoes
    3-Housing
    4-Brushes
    5-Bushes
    6-starter drive

3.clockwise

4. 1-inertia
    2-pre-engaged
    3-gear-reduction

5.

6. Front view of a starter motor clutch.

 

7. The pinion is turning in direction of the arrow 

at a speed higher than it should go when the engine has started.

the clutch allows it co compensate briefly and safely pull away.

8. Series wound starter internal circuit.

9. Designed for low compression motors, produces high torque on low revs and low torque on high revs (vice versa).

10.

Alternators and Charging systems

Man...this one was a doozy, odd to follow but i guess i soaked the info on this.

Well First day of  "charging systems" practical we disassembled an alternator, learnings the innards of how it works. Learning to identify the parts like the rotor, electromagnet, regulator, rectifier, brushes, slip rings etc.

So the alternator works by having electrical energy pass through its contacts turning on the electromagnet and while the rotor inside is run off a belt connected to an engines crank pulley, it gets turned over multiple times rapidly producing an AC current which is then converted to DC current by the alternators rectifier and the output is then controlled by the regulator to not overcharge or overproduce power......to briefly rundown the just of it.

After learning about the innards and how it does its job, the next day we took our newfound knowledge to the real deal...an engine.
Although it was a turn-key on a test bench it was just like the real thing except without the headlights, brakes and all the other fruit on a car.

To start things off we had to do our safety check and safety rundown (rundown being engine instructions etc). Steeltoe boots were check, overalls and open ears check.. i was set to start the first set of instructions.

First we checked if the brakes were on and that it was in neutral before we started our tests. The damned thing was bolted down to a testbench so i doubted it was gunna go anywhere.
Next, preliminary checks were made, charge warning light working-yes, accessories off-yes, visual inspection of the wiring-wiring good, alternator mounting-strong and checking the fusable links-good.
Belt drive inspection, belt in good nick (new), tensioned correctly.

Now we had to do a no load test on the alternator.
First checking the batterys OCV: 12.75v
Regulator voltage spec: 13.5-14.5v
Regulated reading: 14.08v
Amp output for carb'd engines.
Checking the Amp output: 8.8
these test was a text book pass.

Then a load test was required next...
Charge voltage under load-specs: OCV+0.5v= 13.8

The clamp induction meter and a multi meter were needed for the next set of tests.
multi meter is set to 20v DC, clamp induction meter set to 400Amp DC then zero it.

Place the clamp around the B+ cable from the alternator, take the engines rev's to 2000, turn on car accessories besides the wipers and radio.
Now after that i took a clamp meter reading. '
Output Amps reading: 8.1Amps
Charging voltage under load 61.5Amps
Another test pass.

Lastly was the voltage drop tests. Specs at 0.20-0.40v drop only.

To get a fairly accurate reading there needs to be a fair bit of load. So with the engine running with all the accessories on (except the wipers and radio) Using a mutimeter i checked the drop between the battery positive and alternator output. 0.1v

Volt drop between battery negative and alternator body while engine is still running: 0v

Added volt drop total: 0.1v

These tests were a pass.

Charging systems Q&A.

1.

Q1-1 :A stator is a group of stationary conductors, directed in right angles to the rotating magnetic field or rotor.
2: The rotor turns and its magnetic field jumps across to the stators conductors, introducing current into the stators conductors.

Q2-1:A rotor is a rotating electro magnet.
2:The function of the rotor is to rotate and create and eletromagnetic current when combined with the stator, creating AC current.

Q3:The function of the retifier is to convert the AC current into DC current to power the cars accessories and other eletronics.

Q4-1:Delta connection
2: Y-connection.

Q5-1:Delta diode has more amps at low alternator RPM's
2: Y-Diode has more amps at a higher RPM.

Q6:

Q7:

Battery testing

First off is the safety...We the class were all required to wear overalls and hardtoe boots/shoes for our own safety and at some points during the lesson some eye protection, due to this being a Battery involved lesson and batterys have acid in them, well the safety is mostly self-explanatory at this point.

We started things off by learning the basic visual inspection of the battery.
On the battery we had to find the Make of the battery, Battery number, CCA (cold cranking amps) and what types the battery was e.g. Gel cell, conventional, maintenance free, etc.

Next we learnt whether the batteries we had were able to have thier eletrolytes checked easily...this was done by removing the screw caps on top of the battery but if thier were no screw caps the battery was probably maintenance free and had no easy access screw caps.

Afterwards we were taught the basics of a visual battery inspection...
Checking for and common faults e.g. Corrosion on the Terminals, Battery case swelling caused by over-charging, etc.

Now this is where the safety glasses came in to play...Checking the eletrolyte levels of the battery required us to take off those screw caps on top of the battery exposing the cells aswell as the Sulphuric acid inside.
The eletrolytes were observed...the acid inside seemed to be at the right level, and if not, needs to be topped to the right level with distilled water.

The next task was doing a Battery open circuit voltage (OCV) test.
Before really starting this test we needed to make sure the batterys "surface voltage" was dissipated if it was present...Surface voltage occurs when the battery is overcharged and the overcharge is the given reading of voltage on a multi meter, this is not the true voltage reading and must be dissipated to show the true reading.
The range of the multi meter must be set to (DCV) Direct current volts. The result of my battery was a reading of 12.8V, a well charged battery...the state of charge for my battery was recorded down as 100% charged.

Batteries must be over 50% charge or above before any other testing on todays lesson can be conducted.
thankfully my battery was AWESOME compared to some others in the room, Hehe.

The next thing to do after comfirming my battery was good enough to continue was Testing the eletrolyte specific gravity. once again the safety glasses made a return but that wasnt so bad, it would've ruined my morning to get acid in my eyes...anyways back to topic, A Hydrometer (a turkey baster-like thing witha  measurement bulb inside)  is used to conduct this test. The rubber bulb is squeezed to suck in the acid of one of the batteries cells to test, if among the green part of the measurment bulb, its a good cell..if red, then its not so good.

last but not the least of my lessons learning of battery testing is the Load tester.
This one gave me the S**ts as i thoguht i broke something, but later found out it was normal and because the terminals weren't connected firmly enough...anywho, the load tester was to see the batteries ablity to supply cranking voltage. (provided the battery was at least 50% charged)

The load i applied to the battery was 205Amps, the voltage it should hold is 12.4V and is going to be tested for 15seconds... after the test and the slight fright of a smoking, sparking piece of equipment, the readings i recorded are as follows...
The voltage held when load was applied was 10V = A pass for the battery
The current load held was 205Amps = A pass for the battery

in conclusion my battery was awesome and passed all the days tests, and i learned a few new things myself which i found enjoyable.

Excuse me if my work is a little shotty after this point, i wrote out more battery info and the 12Q&A's then the blogger didnt save my work and now i gotta wirte it all again and really cant be bothered, so here goes.

Heres the construction of the Car battery if your curious.

This is the basic construction of the car battery (pictures from the "batteries" powerpoint.)
There was 2 paragraphs of writing but at the moment im a little "edged" to write it out.

Battery Q&A's

1. Powers lights and radio when car is off.
    turns on starter motor.
    powers car alarm

2. A charged battery has "charged" acid and when the battery becomes Dicharged the acid neutralizes until recharged.

3. Checking the batteries electrolites or Taking a hydrometer test.

4. Removing the engines coil wire and starting the engine for 10secs or turning your cars headlights on to a few minutes.

5. 100% State of Charge = 12.60 – 12.7 v
    75% State of Charge = 12.45 – 12.5 v
    50% State of Charge = 12.30 – 12.4 v
    25% State of Charge = 12.15 – 12.2 v

6. Take the batteries CCA and take half of that to get the required load and turn that on the dial of the load meter, after the load meter has been connected to the battery quickly take the reading, you have 15secs before the load meter stars to beep, remove the cables when it does, taking negative off the battery first.

7. 100% State of Charge = 1.240 – 1.260
    50% State of Charge = 1.180 – 1.210

8. Take a multimeter and set it to 30 to 50mA (miliAmps) connect the negative to the (-) on the battery and the positive to the negative cable on the car while leaving the the positive cable still connected to the battery. take the reading in the multimeter.

Picture sourced from "batteries" powerpoint.

9. The terminals of the battery should be cleaned with hot water mixed with baking soda whe the terminals of the battery are corroded or generally dirty.

10. When the battery is charging it can produce Hydrogen inside. if becareful that a naked flame or spark does not set it off as it can cause a fatal explosion.

11. Take your jumper leads and connect red on (+) and black on (-) on the Doner battery, now on the opposite end of the leads connect red on (+) and black on a piece of the engine or engine bay and start the car with the dead battery, Connecting this way will help prevent reseting or surging the cars computer if any present.

12. put a small power source that is specially designed to be connected through the cars cigarette lighter...this will give enough power to keep the cars eletronic memory working until the cars actual battery is changed or recharged.



Individual Circuits

Sorry if my writing is a little up and down, sadly i write the way i speak, its easier to think that way.

First off a Circuit is a Pathway, an electrical pathway if you will.

An individual circuit is a basic pathway containing a Battery (Power source) a switch (to break and connect the circuit at your will), a consumer (bulb or something close to the liking) and a Fuse (to protect the circuit from short circuiting by breaking the pathway when overloaded. The fuse "blowing out".)

I tinkered with this circuit as my first little project for class. i enjoyed messing around with this circuit, brought back memories when i was a kid (but that's me speaking my mind again).

Any who, i placed all the necessary connections together, Power pack (after using a multi-meter to adjust the correct voltage of 12V), fuse, 1 bulb, wiring and the switch, positive connected to positive red and negative black, grounded...flick of the switch and shazam, let there be light!

After my little shine of success (excuse the pun) i was then required to use a Multi-meter to measure the available voltage and voltage drop of the electrical components.

I measured the voltage of the power supply (B+) :12V
Terminal before the switch: 11.97V
Terminal after the switch: 11.97V
Terminal before the bulb: 11.96V
Terminal after the bulb: 0V
The negative on the 12V power supply (N-): 0V

From the results shown i learned that as the voltage passed through the circuit, a little bit of voltage was used along the way towards the bulb. The rest of the available voltage passed through the bulb lighting it and then there was 0V back to the ground.

The voltage drop was the next part to measure.
From B+ of the 12V supply to the input of the switch: 0.02V
From the input of the switch to the output of the switch: 0V
From the output of the switch to the input of the bulb: 0V
From the input to the bulb to the output of the bulb: 11.96V
From the to the bulb to the output of the bulb: 0V


From the results shown here the voltage has passed through all the components and the voltage has dropped a little from passing through the wires and the rest of the available voltage has passed into the bulb lighting it up and going back to ground.


After that, the resistance was the second to last part to measure.
Measuring the amperage, by setting the multi meter to Amps i was able to measure the amperage of the circuit.
Wire before the bulb: 0.34I (amps)


Using Ohm's law i calculated the resistance: Volts divide by Amps = Resistance
                                                                  12/0.34=35.29 Ohm's


And lastly the Watts and/or Power of the bulb.
By measuring the Amperage and Volts of the circuit i was able to calculate the Watts by using 'Power Law'.

Volts x Amps = Watts
12V x 34=4.08W

After the end of the first lesson i had learned all of these things, using a multi meter, what it does, creating a individual circuit, etc.

Safety Briefing 4841 Eletrical.

General Hazards:

-Never remove a Radiator cap while the engine is hot.
-Never go underneath a car when it is only supported by a Jack.
-Beware of Flammable liquids in the workshop.
-Beware of Exhaust fumes as they are highly poisonous to inhale.
-Beware when working near Brakes and Clutches as they might have Asbestos dust hidden away and inhaling Asbestos dust can cause cancer and lung problems.
-Try and avoid skin contact with most liquids in the workshop e.g Fuel, Anti-freeze, Liquid lubricants, etc.
As they can cause skin irritation and other effects.

Special Hazards:

-Beware of Air bags as sometimes they can go off unexpectedly and cause injury.
-Take care when transporting a car Battery as it contains a highly corrosive liquid inside. (Sulfuric acid)
-Take care when working on diesel Fuel Injectors as they supply fuel at very high pressures.

Safety Question Answers...

1. Place Axle stands underneath the vehicle after it has been jacked up.

2. the person underneath the bonnect could get caught on the engine fan and could lose some fingers, get thier hand caught in the cam belt, get hair caught in the fan belt, could get jolted by the spark coil or spark plugs if they are working on it. etc.

3. If oil was poorly poured into the engine and it went on the engine, the engine could later be running and spotaniusly catch on fire when the engine has warmed up, or starting a petrol engine by pouring petrol down the carburator to start it when its cold,a spark from the distributor or coil could start a fire. etc.

4. The person working near a cars airbags could accidently set them off by bumping to hitting the dash or wheel by accident or not carefully removing and the physical damage caused after the airbags deploy, the bag deploys hard enough to possibly knock out the person near the bags and because they may not be sitting in the required position for airbag deployment the persons head and neck could be smacked in an awkward way causing bad injuries. (man thats a long answer).

5. Batteries can produce Hydrogen gas when charging and exposing the battery to a naked flame or spark can set off the gas causing an explosion, becareful when connecting and disconnecting the battery from jumper leads or a charger.

6. Wear protective gloves and dispose after use...or in general stay away from it.

7. Diesel fuel injectors inject fuel at a very high pressure and can penetrate the skin in hands and face and can cause fatal results.

8. Rings and wristwatches are electrical conductors and eletricity can arc to them when working on ignition systems or something close to the matter. They can also catch onto things as your working/ getting your hand caught on something. etc.

9. Hair could get caught on the fan or belts and could tear the hair from your scalp or if your shirt got caught, could strangle you or pin you on the engine and getting tight causing brusing. etc.

10. A slight push could roll it out or onto someone unintentionally, causing someone to get hurt,

11. Pull the pin, aim at the base of the fire and pull the trigger discharging the cO2.

12. Carbon monoxide produced from a running vehicle can be a harmful can to inhale and can kill you, fuel is highly flammable and can catch on fire, it is also irritant to the skin if left exposed on the skin for a long time, the same goes for Motor oil, its flammable and a skin irritant.