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uping power supply current

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MrDEB

Well-Known Member
can a person build a power supply with several 78xx in parelle with each other to increase current?
one 78xx is only good for 1 amp w/ heat sink but if I put 3 78xx in parelle then we have 3 amp capacity??
of coarse add several capacitors
reason is I have a spectrum analizer schematic that I was/ am playing with using 10 - lm3916 chips. 10 leds per chip and a 2watt 15 ohm resistor connected to 9v+ and all the leds. the 3916's are sinkimg current.
I recall audioguru helped with design but the question was raised about power supply for all the LEDs??
I would post schematic but presently on different computer and can't get hoversnap to post attachement??
maybe just wait until I return to Idaho??
 

kchriste

New Member
Forum Supporter
Another method would be to split the LEDs into sections consuming less than 1A and power each section with it's own 78xx.
 

MrDEB

Well-Known Member
Thats a viable solution

when I get back to Idaho, will look at possiablities.
Was surfing the web and found on the mondo-technology site a super probe that has a frequency countey on it. Wonder if I could use this to adjust all my displays and each filter section??
When I get back on my computer I have lots of stuff on my plate.
a digital Theremin using ADC and a MCP41010 digital pot
ordering PICs for experemintation with the two books I ordered on PICs
Doing same following PCBHEAVEN examples
Getting the bugs out of my critter ridder
getting it ready for a vechile ap
tired already!!
 

MrDEB

Well-Known Member
Thanks, will look over link

I purchased PICBASIC PROJECTS by Ibrahim Dogan
and
PIC in PRACTICE by D. W. Smith
also took great interest in the website suggested by ??
PCB Heaven I think
got to start somewhere and the projects for the 18F over at mondo-technology are really interesting.
can't waiot to get little juney out and get her a workout.
I purchased 5 18F1320's from Allied Electronics for under $3 each
maybe learn something about converting from 16F to 18F
wouldn't hurt
Yo blueroom, I am still thinking about your manual on the junebug
great tool that deserves a complete manual. Like adapter boards, better explanation about dip switches, etc.
something catered to a newbi
 

blueroomelectronics

Well-Known Member
I agree about the manual, let alone a complete book. I've been playing with priority interrupts and wrote the following little demo. (Even with code tags it's sloppy thanks to the MPLAB editor)

Button #1, LED #1 are high priority
Button #2, LED #3 are low priority

You can press #2 , #1
But can't press #1, #2

Turn off DIP 1 so the reset switch works after programming.
Code:
        list     p=18F1320
        include <p18F1320.inc>
        CONFIG     OSC = INTIO2, WDT = OFF, LVP = OFF

        org     0x000                ; reset vector
        bra        Init                ; goto initialize             

        org     0x008                ; high priority interrupt vector
        bra        HiInt                ; goto high priority interrupt

        org     0x018                ; low priority interrupt vector
LowInt    bcf     TRISA,6                ; Light LED 3
        bcf     TRISA,7              
        bsf     TRISA,0                 
        bsf     LATA,6                      
        bcf     LATA,7                     
        bcf        INTCON3,INT2IF        ; clear the INT2 interrupt flag
Loop1    bra        Loop1                ; endless loop
        retfie

HiInt    bcf     TRISA,0                ; Light LED 1
        bcf     TRISA,6              
        bsf     TRISA,7                 
        bsf     LATA,0                      
        bcf     LATA,6                     
        bcf        INTCON,INT0IF        ; clear the INT0 interrupt flag
Loop2    bra        Loop2                ; endless loop
        retfie

Init    clrf    INTCON2                ; enable PORTB pullups, falling edge interrupts
        setf    ADCON1                ; make all I/O digital
        setf    TRISA                ; turn off all the LEDs
        bsf        INTCON,INT0IE        ; enable INT0 (RB0)
                                    ; RB0 is always high priority
        bcf        INTCON3,INT2IP        ; INT2 (RB2) low priority
        bsf        INTCON3,INT2IE        ; INT2 interrupt enable
        bsf        RCON,IPEN            ; interrupt priority enable
        bsf        INTCON,GIEL            ; low priority interrupt enable
        bsf        INTCON,GIEH            ; high priority interrupt enable
Loop3    bra        Loop3                ; endless loop    
        END
 

bountyhunter

Well-Known Member
can a person build a power supply with several 78xx in parelle with each other to increase current?
one 78xx is only good for 1 amp w/ heat sink but if I put 3 78xx in parelle then we have 3 amp capacity??
of coarse add several capacitors
reason is I have a spectrum analizer schematic that I was/ am playing with using 10 - lm3916 chips. 10 leds per chip and a 2watt 15 ohm resistor connected to 9v+ and all the leds. the 3916's are sinkimg current.
I recall audioguru helped with design but the question was raised about power supply for all the LEDs??
I would post schematic but presently on different computer and can't get hoversnap to post attachement??
maybe just wait until I return to Idaho??
Why not make your life simple and just buy a 3A regulator? There are lots to choose from.
 

MrDEB

Well-Known Member
3A=yes 9V=no

looked at Mouser and no go on 9v regulator at 3amps
using a 7809, and 2 mje3055, aswell as several 1 ohm resistors for under $4
as per link I posted.
a LM323T = $1.27 but not 9v?? need to recheck my figures and data sheets.
As stated I have 10 LM3916's with 10 LEDs per. the LM3916's are sinking.
In my schematic I have 1=15 ohm resistor connected as 9+v to the LEDs.
why I came up with this configuration?? Audioguru was helping design and as per his suggestion (pretty sure it was audioguru, if not I apologize)
would love to post schematic but not on my computer.
The multiple 7809s sounds viable as well, then I don't need the 1 ohm resistors but will have to redesign the boards with several 7809s incorporated or ??
 

bountyhunter

Well-Known Member
The multiple 7809s sounds viable as well, then I don't need the 1 ohm resistors but will have to redesign the boards with several 7809s incorporated or ??
That's the best solution because it spreads the power out. be sure to make a PC area to lay the 78 over and solder down as a heatsink. One square inch of copper should be enough.
 
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