There's a lot of types of power supplies in the internet, but when we need to connect especial circuits that consumes a lot of current, it becomes very useful to use a good and efficient power supply.
A simple 78XX linear regulator can support without discipator for a normal consume, but if you wanna try to use more current this proyect can help you.This instructable will help you to make a power supply of 5 V & 3.3V @ 1.5 Amperes (With heat sink).
Is very important that you should to use a 2-3 Amperes Transformer at leats for "supply" the current that tha "charge" requiers.
D1 IS CONNECTED TO THE REGULATOR FOR TO COMPENSATE THE LITTLE MORE ELEVATED VOLTAGE OUTPUT FOR THE B-E DIODE UNION. AND TO MAINTAIN THE 5.00 V REGULATED
IF YOU TRY THE CURRENT THAT IT CAN OBTAIN US THE OHMS LAW V=R*I
I=V/R IF WE HAVE 1 AMP THE VOLTAJE IS 5 VOLST WE USE A RESISTANCE OF 5 OHMS
A 5 WATS AT LEATS FOR THE PROBE.
P=V*I =5(1.5)= 7.5 W
AT THE MAXIMUN WORK THE VOLTAJE DECREASES 0.2 V BUT IS STILL USABLE. THIS INFO IF FOR THE IC 7805 AND LT1117.
Step 1: SCHEMATIC AND PCB
Here's the schematic and the PCB look like this.
Now you see a transformer it would be since 6-12 volts @ 2 Amp. It has a in-line diode bridge of 2 A. The filter electrolitic capacitors, for reduce "noise" in the voltage.
When you put the caps in the Cooper table respect the polarity In the body of the cap is marked with a line (--) where de NEGATIVE is.
*The regulator is and L7805 TO-220 it has and dioide betwen PIN1 (INPUT) AND PIN3 (OUTPUT). *The series diode betwen pin 2 (GND) and CIRCUIT GND is for compensate the loss caused by The union B-E of the transistor TIP14* *The transistor is a common TIP41X medium power 6A.
To put a good heatsink in the TIP41 it becomes really hot when it works a fully capacity, (1.5 Amp). it provides the current of your power supply :)
Step 2: Theory of Operation and Part List.
I use the TIP41 transistor. In principle, it can Supply Current about 2A (Says it's Datasheet
high enough to use. I like this number because it’s cheap, efficient, reasonable.
Most of 1,2,3,4,5 A use PNP Transistor (unpopular) and sometimes more expensive that NPN ones.
The transistor configuration is a common base that's say the theory os circuits a transistor thtat is used in this configuration Base to GND EMITTER AND COLLECTOR as input and output the gain is in CURRENT
Let's see a bit of theory:
in electronics, a common base (also known as grounded-base) amplifier is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a current buffer or voltage amplifier.
In this circuit the emitter terminal of the transistor serves as the input, the collector the output, and the base is connected to ground, or "common", hence its name. The analogous field-effect transistor circuit is the common gate amplifier.
As current is sunk from the emitter this provides potential difference so causing the transistor to conduct. The current conducted via the collector is proportional to the voltage across the base-emitter junction, accounting for the bias, as with other configurations.
Therefore, if no current is sunk at the emitter the transistor does not conduct.
The 3.3 Volts Voltage Regulator
There are various kinds of 3v3 regulators, mostly used in SMD, I choose the Trought-Hole T0-220 Package
is and LM1117 3V3 RE Linear Technologies
Component list of 12v to 5v voltage regulator
IC1___LM7805___5V dc regulator IC
Q1___ TIP41____2A 50V NPN power transistor
C1____1000uF 35V___Electrolytic Capacitor
C2____0.1uF 50V___Ceramic or mylar capacitors
Diode LED1____LED any color as you like
R1____820 ohms 0.25W
Step 3: Real Measures.
When you connect the power suplply and ready to work you can probe the maximun power that it can to deliver in a circuit before you connect it to the supply
Use simple Ohm's Law
Imax=1500 mA = 1.5 A and the output voltage is aprox. 5.01 volts the resistance you need is
R=V/I = 5/1.5 = 3.333 Ohms and the commecial value is aproc 3.3 Ohms
And the Power of the resistor is Pmax=V*I = 5.01*1.5= 7.5 Watts but you can put a 5w resistor for the probes only.
And the same with the 3.3 volts regulator:
Imax=1500 mA = 1.5 A and the output voltage is aprox. 3.28 volts, the resistance you need is
R=V/I = 3.28/1.5 = 2.18 Ohms and the commecial value is aprox 2.2 Ohms
And the Power of the resistor is Pmax=V*I = 3*1.5= 4.5 Watts but you can put a 5w resistor for the probes only.
Step 4: The Files... Ready to Print and Make Your Own C:
Here the files of the artwork and if you wanna try the silk screen artwork the file is included too.
I taken a bit of pictures of the Copper Plate before it was made, check it out :)
Step 5: Final Circuit Without Enclosure
Here the functional and final circuit.
I know the important of and enclosure, but i have to do more things and about the time, i don't hace too much, but you can modify,decorate as you want, please send me pics for to motivate me to make more instructables.
-Your favs and views feed my heart :)