★ASSEMBLING A POWER SUPPLY★: ★★ Soldering ★★

dated October 2, 2011 (Sun)

So there you have it, after an almost month-long preparation, the PCB was finally set. We deserve stars ★★★. And now that the PCB is ready, we’re moving on to the next level which is the most crucial one, TEN-TEN-NEN-NEN ----the SOLDERING part.

SOLDERING

As been said earlier, we asked for my cousin’s assistance for assembling the Power Supply. This was because we only had one shot at our project and of course, we didn’t want to risk it by doing it on our own, otherwise, we might as well pay for another P680.00. Besides that, there were lots of inconveniences and circumstances which deferred the continuation of our project-making. So we both decided it’d be best if we consult from someone who’s capable enough at the same time, not too inclined with the field so we could catch up with him.

G. Tools and Things Needed:

Ø Solder

Ø Soldering Iron

Ø Wires

Ø Power Supply Set:

4 Diodes

2 Capacitors

Resistor

Transformer

Selector Switch

Fuse

Switch

Plug

Casing

H. Soldering the COMPONENTS to the PCB

Diodes, electronic devices that allow the passage of current in only one direction, were the very first components that were soldered. The first two diodes were soldered in forward bias then the other two left were soldered in reverse bias. The anodes of the first two diodes soldered in Forward Bias were on the positive side of the DC output so that a positive current will be created and as for the other two diodes left; they were soldered in Reverse Bias, that is, they were situated vice versa so similarly, a negative current will be created. After the diodes, the capacitors - used for storing electrical charges - were soldered in a fashion wherein the two negative legs of the capacitors were soldered opposite each other which basically meant that the positive legs were apart. Note that the shorter legs of the capacitors signify the negative part. On the other hand, the longer legs signify the positive part of the capacitors. Next component soldered was the resistor which limits the flow of direct or alternating electric current. It wasn’t hard to solder the resistor since there was only one of its kind, also it didn’t require some specific positioning.

I. Soldering Wires From the Transformer to the Selector Switch

After soldering the components, we had to mount the transformer first on the casing which later served as the base of the power supply. That was necessary before we could continue soldering. When we finally positioned the transformer, we carefully screwed it to the base. We made sure the transformer was tightly secured in its place.

We then dealt with the transformer which is the first element necessary in a power supply; it steps up or steps down the input voltage to a level suitable for the operation of equipment. A secondary function of the transformer is to provide electrical ground insulation of the device from the power line to reduce potential shock hazards. The transformer had 12 legs, 6 on the input and the other 6 on the output. The 6 legs on the output part are designated with different voltage numbers namely; 0V, 3V and 4.5V on the upper portion and 6V, 9V, and 12V on the lower portion. The wires for each of the legs were connected correspondingly for the selector switch - used to choose a definite switch or change a different switch from another switch. Say for instance (regarding the correspondence of wires), the wire linked to the 12V leg of the transformer must be linked to the 12V holder of the selector switch.

J. Soldering the Other Parts (Fuse, Switch, Plug, etc.)

Next were the Negative and Positive Terminals which were connected thru wires with the PCB's direct current output. These terminals will determine whether the Power Supply functions or not.

The FUSE was connected to the transformer and the plug wire to protect the circuit from the effect of excessive current. Its essential component is usually a strip of metal that will melt at a given temperature. A fuse is so designed that the strip of metal can easily be placed in the electric circuit. If the current in the circuit exceeds a predetermined value, the fusible metal will melt and thus break, or open, the circuit.

The SWITCH had three holders. The first one was for the transformer; the second for the plug wire and; the third was supposedly for the LED of the Power Supply. Unluckily, we didn’t include such because we were advised that it wasn’t compulsory. When the switch is opened, the connection is broken, electric current cannot flow. Consequently, when the switch is closed, electric current can flow.

The PLUG, connected to the fuse and the switch, will of course enable us to use the power supply.