"In
Circuit"
ELECTROLYTIC
TESTER
Page 2:
go to: P1
P3
P4
CONSTRUCTION,
Burning the program
into the chip,
and Using the Tester
CONSTRUCTION
All the components fit on a small PC board with 4 leads going to a small
plug that fits on the 5x7 display. The plug has 5 pins but the second pin
from one end is not used. It is best not to connect a wire to this pin so you can see which way to connect the plug. At the other end of the
ribbon cable, the lead does not solder to the board.
Two leads are also needed to connect the electrolytic-under-test to the
board. One lead has an alligator clip and the other is an E-Z
clip.
The two green LEDs serve as ON indicators as well as a zener reference
voltage for the correct operation of the circuit. The only other
components are a transistor and 4 resistors. What more can we say about
construction? Check the correct placement of the LEDs and transistor. Make
sure your soldering is neat and don't overheat the parts. Connect the 4
wires (5-core ribbon cable) to the board and fit a plug to the other end.
The 5-pin socket goes on the 5x7 Display.
USING THE ELECTROLYTIC TESTER This concludes the
project but it should be just the starting point for you to design another
project around the 5x7 Display. The first thing you will need is the Experimenter
MkIII PC board and some components.
There are lots of
different projects that can be interfaced to the 5x7 Display, in a similar way
to the Electrolytic Tester.
Connect the earth clip to the
negative rail of the equipment you are testing and place the E-Z clip on the
positive of the electrolytic you are testing. Press button "A" on
the 5x7 project and the program will charge the electrolytic and measure how
long it takes to discharge. The display will give a readout in "u"
(microfarad). If the reading is lower than expected, it could be due to the
surrounding circuitry affecting the reading or a dry electro. Remove it,
connect the test leads directly and push button "A" to re-test.
Here are three more simple projects:
- 3-digit customer counter using an infra-red beam.
- Timer for sports events.
- Count-down counter for slot cars, rocket launching, etc.
All these projects need only a few "font-end" components and the 5x7
Display. The Experimenter Board is only used for the first stage of
development. Talking Electronics has a range of Designer Boards containing a
matrix of holes and lands for building a circuit or you can design a PC board
and transfer the parts to the new board. The idea is the parts are removed
from the Experimenter Board and it is re-used for the next project.
Electrolytic Tester PC board
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THE PROGRAM
The program needs a lot of discussion as it is one of the main reasons for the project.
There is a little more effort required to get this type of program running due to the external components having a delay value that is unknown.
Of course you can sit down and mathematically work out how long it will take to discharge a 22u electrolytic from 3.8v to 0v via a 220R resistor but our Microcontroller Course is designed to get you through electronics without involving complex mathematics.
You can do exactly the same by creating a delay routine (at LoopX and LoopY) and counting how many times the program executes this delay routine. The initial answer I got for 22u was 005. I decreased the delay values until I got 22. I then placed a 47u on the Tester and miraculously got 46! A 100u electrolytic produced a readout of 99. I checked a 10u on a professional capacitance meter and got a reading of 11.76u. The tester produced a reading of 12! I expected a conversion table would be needed to take into account the non-linearity effects of charging the electro but the program did not require it.
Electrolytic values are inherently non-accurate and could be as much as +20% or -20% of the stated value. However with the enormous accuracy of modern machinery, a batch of 100u electrolytics gave readings of 98, 99, and 100. Buy re-reading the electrolytics, I got the same values and proved the repeatability of the circuit.
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Program
for "In-Circuit" Electrolytic
Tester (add-on for 5x7 Display) ;PIC16F84 chip Start ORG 0x00 BSF 03,5 ;Go to page1 for setting-up the ports MOVLW 02h ;Put 02 into W MOVWF 05h ;to make RA1 input, others output BCF 03,5 ;Go to page0 for programming GOTO Main Table1 ADDWF 02h,1 ;Add W to Program Counter RETLW 3Eh ;0 RETLW 41h RETLW 41h RETLW 41h RETLW 3Eh RETLW 00h ;1 RETLW 10h RETLW 20h RETLW 7Fh RETLW 00h RETLW 27h ;2 RETLW 49h RETLW 49h RETLW 49h RETLW 31h RETLW 22h ;3 RETLW 41h RETLW 49h RETLW 49h RETLW 36h RETLW 0Ch ;4 RETLW 14h RETLW 24h RETLW 7Fh RETLW 04h RETLW 7Ah ;5 RETLW 49h RETLW 49h RETLW 49h RETLW 46h RETLW 3Eh ;6 RETLW 49h RETLW 49h RETLW 49h RETLW 26h RETLW 40h ;7 RETLW 47h RETLW 48h RETLW 50h RETLW 60h RETLW 36h ;8 RETLW 49h RETLW 49h RETLW 49h RETLW 36h RETLW 32h ;9 RETLW 49h RETLW 49h RETLW 49h RETLW 3Eh RETLW 00h ;This routine charges the electro Charge MOVLW 08h MOVWF 0Ch BSF 05,0 Delay2 DECFSZ 0Dh,1 GOTO Delay2 DECFSZ 0Eh,1 GOTO Delay2 DECFSZ 0Ch,1 GOTO Delay2 GOTO Dis ;00 to 999 COUNTER Dis CLRF 11h ;11h is units file. Start=0 CLRF 12h ;12h is 10's file. Start=0 CLRF 13h ;13h is 100's file. Start=0 CLRF 26h ;1's pointer in table1 CLRF 27h ;10's pointer in table1 CLRF 28h ;100,'s pointer in table1 BCF 05,0 ;Make line LOW to discharge electro NOP ;Give the circuit time to settle down NOP ; and produce 000 readout if no NOP ; electrolytic is connected NOP NOP NOP Dis1 BTFSC 05,1 RETURN ;Electro discharged MOVLW 08h MOVWF 1Bh LoopX MOVLW 10h MOVWF 1A LoopY DECFSZ 1Ah,1 GOTO LoopY DECFSZ 1Bh,1 GOTO LoopX INCF 11h,1 ;Increment the 1's file INCF 26h,1 INCF 26h,1 INCF 26h,1 INCF 26h,1 INCF 26h,1 MOVLW 0A XORWF 11h,0 BTFSS 03,2 GOTO Dis1 ;File 11h is not 10! CLRF 11h ;Zero the digits file CLRF 26h ;Zero the pointer for 1st digit INCF 12h,1 ;Increment the 10's file INCF 27h,1 INCF 27h,1 INCF 27h,1 INCF 27h,1 INCF 27h,1 MOVLW 0A XORWF 12h,0 BTFSS 03,2 GOTO Dis1 ;File 12h is not 10! CLRF 12h ;Zero file 12h CLRF 27h ;Zero the pointer for 2nd digit INCF 28h,1 INCF 28h,1 INCF 28h,1 INCF 28h,1 INCF 28h,1 GOTO Dis1 ;"Digit1" Moves 5 bytes of data from Table1 ; to output to produce a digit ; It scans the Display ONCE ; - the Main program repeats with 60h loops Digit1 BSF 05,1 ;Reset 4017 NOP BCF 05,1 MOVF 28h,0 ;Copy 28h to W MOVWF 23h ;28h copied to 23h for temp incrementing MOVLW 05 MOVWF 18h ;5 cycles of Loading count file 18h Digit1A MOVF 23h,0 ;Copy 23h to W CALL Table1 MOVWF 06h ;output the table value CALL Del INCF 23h,1 DECFSZ 18h,1 GOTO Digit1A RETURN Digit2 BSF 05,1 ;Reset 4017 NOP BCF 05,1 MOVF 27h,0 ;Copy 27h to W MOVWF 23h ;27h copied to 23h for temp incrementing MOVLW 05 MOVWF 18h ;5 cycles of Loading count file 18h Digit2A MOVF 23h,0 ;Copy 23h to W CALL Table1 MOVWF 06h CALL Del INCF 23h,1 DECFSZ 18h,1 GOTO Digit2A RETURN Digit3 BSF 05,1 ;Reset 4017 NOP BCF 05,1 MOVF 26h,0 ;Copy 26h to W MOVWF 23h ;26h copied to 23h for temp incrementing MOVLW 05 MOVWF 18h ;5 cycles of Loading count file 18h Digit3A MOVF 23h,0 ;Copy 23h to W CALL Table1 MOVWF 06h CALL Del INCF 23h,1 DECFSZ 18h,1 GOTO Digit3A RETURN Del DECFSZ 1Bh,1 GOTO Del MOVLW 00h MOVWF 06 BCF 05,0 ;Clock the 4017 to the NOP ; next output BSF 05,0 RETURN Delay MOVLW 04 MOVWF 1B Delay1 DECFSZ 1Ah,1 ;Delay for main program for scanning GOTO Delay1 DECFSZ 1B,1 GOTO Delay1 RETURN ;MAIN ROUTINE Main CALL Dis BSF 03,5 ;Go to page1 for setting-up the ports MOVLW 1Ch ;Put 1C into W MOVWF 05h ;to make RA2,3,4 input CLRF 06h ;Make all output BCF 03,5 ;Go to page0 for program Main1 MOVLW 60h ;60h loop delay to show 1st digit MOVWF 1Ch Main2 CALL Digit1 DECFSZ 1Ch,1 GOTO Main2 MOVLW 20h ;Blanking after 1st digit is displayed MOVWF 1Ch Main3 CALL Delay DECFSZ 1Ch,1 GOTO Main3 MOVLW 60h ;Delay to show 2nd digit MOVWF 1Ch Main4 CALL Digit2 DECFSZ 1Ch,1 GOTO Main4 MOVLW 20h ;Blanking after 2nd digit is displayed MOVWF 1Ch Main5 CALL Delay DECFSZ 1Ch,1 GOTO Main5 MOVLW 60h ;Delay to show 3rd digit MOVWF 1Ch Main6 CALL Digit3 DECFSZ 1Ch,1 GOTO Main6 MOVLW 70h ;Blanking after 3rd digit is displayed MOVWF 1Ch Main7 CALL Delay DECFSZ 1Ch,1 GOTO Main7 BTFSS 05,2 ;Is button A pushed? GOTO Main1 ;No. Repeat routine GOTO Start ;Yes END |
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|
You will also need IC-Prog
program to burn the chipYou should also go to the section "Burning a Chip." This section explains how to load the PIC chip with a .hex file.
Go to: Electrolytic
Tester "stand-alone" version using a PIC12c508A (page3)