Introduction: BUILD a SMD 7805 PCB REGULATOR
hello and welcome to another basic but useful instructable
Have you wondered to give a try to solder SMD components, or maybe to create a mini PCB for an 78XX voltage regulator?
Say no more...
I'll show u how to make a mini PCB with a beautiful led indicator, let's get started.
Step 1: Materials List
The components shown here can be recycled from any PCB with SMD component, all can be salvage from electronic garbage, if you have the money you can buy it from Radioshack or Tandy electronics.
1x Free time (around 20 minutes) :)
1x DIGITAL MULTIMETER
1x 5X5 CM PCB COPPER PLATED (ONE SIDE)
1X SOLDER WRAP OR DESOLDER GUN TO QUIT EXCESS SOLDER (JUST IN CASE)
1X 7805 VOLTAGE REGULATOR IN A D^2 PAK PACKAGE
1X 1K SMD RESISTOR PACKAGE (0603)
1X 0.33 uF SMD CERAMIC CAPACITOR PACKAGE (1210)
1X 0.1uF SMD CERAMIC CAPACITOR PACKAGE(1210)
1X 1n4007 SMD DIODE PACKAGE (M7 OR HT M7 LABELED)
1X SMD LED PACKAGE (1206)
1X 2 PIN TERMINAL BLOCK (SCREW TYPE) (THT)
SOLDER, 25W or less soldering iron and and a little brush teeth for cleaning :)
Step 2: DOWNLOAD AND ETCHING THE TINY PCB
You can download all the files from my dropbox link:
or just click in the PDF file linked to this step :)
Step 3: CIRCUIT SCHEMATIC
The schematic is really basic, and yes you can download de LM7805 Datasheet to see the recommend components for the circuit
C1=0.33uF at the input of the voltage regulator (pin 1) help to give stability for the transcient currents and voltage peaks from the input.
C2=0.1uF at the output of the voltage regulator (pin3) help help to give stability for the transcient currents and voltage peaks from the output.
C1&C2 are recommended from the manufacturer (ST, Ti, and others).
D1= 1N4007 help to protect the voltage regulator from reverse bias and short circuit intentionally or not at the output from own aprecciated voltage regulator, gives a longer life to the regulator.
terminal blocks should be labeled to identify the GND VCC IN AND +5V :)
Step 4: SOLDERING 7805 VOLTAGE REGULATOR AND 1N4007 DIODE
- Press the regulator to the clean pcb and hold it with an alligator clip or something like that
-Apply a little amount of solder to one pin and let dry
-Now the other pin
*check the correct polarity of the diode (anode or positive shall be connected to pin3 (output of the voltage regulator), you can indentify the cathode from the little diode (is labeled with a little strip on the side) or you can use a multimeter in a diode scale and read about 0.7 Volts forward biased and 0 or infinite reversed biased.
Step 5: SOLDERING THE CAPS
Now it`s turn to solder the little tiny ceramic capacitors, it doesn't have polarity.
So you can only check the correct align and no short circuit between the tracks, i really recommend you to solder one side or pad from one cap, let the solder dry and to solder the other side or pad. this process is with both caps and should be tested with a multimeter in continuity scale to looking for some mistake (it shouldn´t be continuity between the pins from both capacitors.
Step 6: SOLDERING THE SMD 1K RESISTOR
-Put in place the resistor as shown in the picture above.
-Now if you feel solder excess you can quit a little with desolder wire.
-Try solder one pad from the smd resistor, let dry, and solder the other pad, if you feel the component is not correct aligned, apply a little time the soldering iron very carefully to the both sides of the resistor and try to aligne it correctly :)
Step 7: SOLDERING THE SMD LED and TERMINAL Blocks
-First of all, if you don`t have very good eye, try this:
-Use a multimeter DMM to in a diode scale
-Put the tips as shown in the picture above, one by side and check in which polarity the led turns on.
-Mark or label the positive or negative and keep it in mind before soldering :)
-Use a little drill for to solder the 2 terminal blocks to the PCB (identify the positive and negative from both sides)
*Before connect the DC >5V power supply check all the tracks and the diode, to ensure all it`s ok.
Step 8: SOLDERING THE GND (GROUND)
-Only apply a little amount of solder to the metal and flux or soldereing paste to gnd of the pcb and the regulator
CAUTION: Don't do this much time (>10 seg) because you could damage the voltage regulator.
Step 9: FINAL RESULT
-Once you finished the soldering time, clean the circuit with a little teeth brush and some of soap and let dry completely.
-Connect the input to and unregulated DC voltage (>5.5 V) and obtain a beautiful 5.00 Volts regulated, pretected and illuminated PCB.
Thanks for to see my instructable, i really aprecciate it, see you the next time :)