Nuts and Bots

Baby Reminder prototype

2014-08-20T00:06:00.000-04:00

Some quick pics of a prototype I have been working on. It reminds you to check if you have a baby onboard when the car engine is turned off by playing a lullaby tune. It works on power ports that turn off or stay on when the key is removed by sensing voltage levels and auto calibrating to your vehicle. The green led turns on when the unit is armed and working. When the engine is turned off, after a delay of 2.5 seconds the green led turns off and the tune is played. I'm still tweaking the program parameters.

Picaxe 20M2 cheat sheet

2014-07-24T23:38:00.000-04:00

I just finished making a cheat sheet for my favorite Picaxe chip, the 20M2. I figured I would share it here for those interested. It is posted on the Picaxe forum website so you need to be a member to get it I think.

Picaxe 20M2 Cheat Sheet

New Workbench!

2013-10-16T22:55:00.002-04:00

I just finished building my new electronics lab workbench downstairs in the basement. I really like it. I used the 2x4 Basics kit from Amazon.com which lets you easily create a custom workbench using only 2x4's and plywood sheets. I used a high quality finished oak 3/4" plywood for the top. The basement is unfinished and a bit dingy so I decided to make the bench enclosed. It is 6 feet wide and 3 feet deep. I also installed a True-HEPA air purifier which creates a positive pressure inside the benchtop area, especially when it is closed up. I am trying to achieve an equivalent of an ISO 6 or Class 1000 clean space. I want it clean so I don't get any dust buildup on my parts and test instruments. I'm also looking to do some vacuum chamber experiments with metal film deposition and I need clean air for my 2 stage rotary oil sealed vacuum pump. I just need a Bell Jar and test stand now...

Impedance Tester alpha build

2013-08-28T22:20:00.000-04:00

IT'S ALIVE!

I finally got the pieces together and assembled the components onto the main board of the impedance tester project.
I did some initial testing of each AD circuit (MCP3202 12-bit for voltage and ACS713 hall sensor for current) and then the FET on/off test. Everything worked perfectly! So I've got some very beta code going using the terminal as the UI. Looks good so far! I am getting consistent results within +/- .3 milliOhms so I am very pleased! I am cycling ~10 amps of load (~1.2 Ohm resistance) and using a kelvin style hookup to keep the load current from interfering with the voltage sense at the cell/battery. I need extreme accuracy and a sensing resolution of .001 volts in order to get a valid internal resistance measurement. As always leave a comment if you want me to post the code.

' Program By Michael Bentley.

#picaxe 20x2
#Terminal 9600
#No_Table
#No_Data
#freq m4

Symbol ADVal = W0

Symbol Channel = B2
Symbol Q = B3
Symbol Config = B4
Symbol AMP = W3
Symbol V1 = W4
Symbol V2 = W5
Symbol V3 = W15
Symbol V4 = W12
Symbol U = B12
Symbol W = B13
Symbol X = B14
Symbol Y = B15
Symbol Z = B16
Symbol VOLT = W10
Symbol VOLTSTART = W11
Symbol IMP = W13
Symbol IMP2 = W14

Symbol FET = C.5
Symbol SCK = B.7
Symbol CS = B.0

HSPISetup spimode00, spimedium
Low SCK
High CS
Pause 500

SerTxD ("Impedance Tester", CR, LF, LF, "by Michael A. Bentley",CR, LF, LF)

Main:

Do
pause 500
Channel = 0
GoSub ADMeas
VOLTSTART = ADVal
V1 = ADVal * 3
V2 = ADVal * 5/10
'V3 = ADVal * 0/100
V4 = ADVal *5/1000
VOLT = V1+V2+V4
BINTOASCII VOLT,U,W,X,Y,Z
SerTxD (U,W,".",X,Y,Z," Volts - Press any key to start test",CR,LF)
SerRxD [3000,Main],Z
IF VOLTSTART > 275 then Goto Test

Loop

Test:

serTXD ("Testing...")
V1 = VOLTSTART - 275
high FET
for X = 0 to 255
channel = 0
gosub ADMeas
if ADVal < V1 then
low FET
SerTxD ("ABORT-Unstable Voltage!")
goto Main
endif
pause 12
next X
pause 50
readadc10 B.1, AMP
AMP = AMP - 103

Channel = 0
GoSub ADMeas
V1 =ADVal
pause 10
low FET
pause 100

Channel = 0
GoSub ADMeas
ADVal = ADVal - V1
V1 = ADVal * 3 * 10
V2 = ADVal * 5
V3 = ADVal * 0/10
V4 = ADVal * 5/100
VOLT = V1+V2+V3+V4
VOLT = VOLT *10
V1 = AMP * 2
V2 = AMP * 6/10
V3 = AMP * 4/100
AMP = V1 + V2 + V3
IMP = VOLT/AMP * 10
IMP2 = VOLT//AMP *10 /AMP
IMP = IMP +IMP2
BINTOASCII IMP,U,W,X,Y,Z

SerTxD (LF,W,X,Y,".",Z," mOHM", CR, LF, LF)

pause 500

Goto Main

ADMeas:

low B.0
hspiout (001101) ' CH0
hspiin (b1,b0)
high B.0
w0=w0/8

Return

Shocker!

2012-08-25T17:40:00.000-04:00

WARNING!!! High voltages present! Use caution!

My son asked me a while ago if we could build a device that would shock people. I said "why not" and drew up this little circuit. We then cobbled it together from some pieces I already had. This is not a debilitating device, it just gives a potent "what the heck!" kind of shock. It has a peak impulse of +1250V when the field in the transformer collapses and I am pulsing at 1000Hz. I checked the maximum current draw with the secondary shorted and measured 4.7milliamps so it is under the "heart safe" 5 milliamp limit. The driver is a Picaxe 08M. The first test was disappointing because the frequency was low and timing of the magnetic field setup and collapse was off. I could just hold the wires and feel the pulses.Once I got the timing tweaked using an o-scope by changing the code in the micro, watch out! This sucka bites! I also had to remove the diode across the transformer as it was absorbing the field collapse impulse which turned out to be much stronger than the setup inrush voltage pulse. Go figure, I should have known this given the time to setup the field from the apparent high impedance source of the battery on the primary was longer than the field collapse rate on the secondary and all that energy over time was being released much faster during the field collapse.

WARNING: Potentially hazardous voltages may be present within this circuit.Clicking read more will allow you to see the inside pictures and schematic. If you decide to build this circuit please be careful and responsible. You are responsible as the creator of the device for it's proper use and operation. If you are under 18 you MUST consult with your parent/guardian before building this project. Failure to do so will result in suspension of hobbyist activities and banishment from the lab!

PCB arrival

2012-08-24T20:29:00.002-04:00

Hooray! My new custom circuit boards for my battery impedance tester project just arrived. Now I can start assembling a prototype and get some code going on the micro (Picaxe 20X2). I should be able to achieve 350 micro-ohm resolution, which should be good as most of the batteries I intend to test are 4000 uOhms and greater when new. This should give me a good idea of the battery health. I intend to cycle the 1 Ohm load across the battery and measure the voltage drop with the 12-bit ADC. I haven't decided if I'm going to ramp it up PWM style or just switch it on, read voltage, then back off. I will have to try both ways and see what works best.

Battery Charger - PWM controlled.

2012-08-24T00:43:00.003-04:00

This is my latest project I just completed. It is a multi-channel lead acid battery charger. It can be used for VRLA, gell cell and wet cell types. It is designed to charge battery jars with a nominal voltage between 4 and 12 volts. It will also work well with any battery type requiring a constant voltage float charge. It has built in limiting circuitry to keep each channel at or below 1.25 amps. The individual channels may be paralleled for higher current. Once the set voltage is adjusted and the channel is turned on, the charger will try to drive to the set voltage while automatically current limiting. As the set voltage is reached the current diminishes to a fractional amount that is required to "float" the battery at that setpoint. The system has automatic fault detection for over/undervoltage and battery disconnect as well as open cell detection and will automatically turn off the affected channel.

The charger is built around a modular approach whereby the charger cicuitry is on small charger PCBs that connect to a main 24V supply and are driven via a PWM signal from a microcontroller. They also provide a voltage feedback to the microcontroller via ADC input. A 4x20 matrix serial lcd screen and 4 membrane type buttons are used for HMI. The microcontroller used is a Picaxe 20M2 mounted on a Kiwi Patch board. The power supply is by Mean Well and there is a cooling fan mounted left side to keep everything running cool.

symbol PWR1 = bit0
symbol PWR2 = bit1
symbol PWR3 = bit2
symbol PWR4 = bit3
symbol FLT1 = bit4
symbol FLT2 = bit5
symbol FLT3 = bit6
symbol FLT4 = bit7
symbol i= b1
symbol ADC =W1
symbol PWM1 = W2
symbol PWM2 = W3
symbol PWM3 = W4
symbol PWM4 = W5
symbol SP = W6
symbol SP2 = W7
symbol SP3 = W8
symbol eval = W9
symbol ADC1 = W10
symbol ADC2 = W11
symbol ADC3 = W12
symbol ADC4 = W13
rem temporary setpoints placed in NV memory-remove in final
'SP = 650
'write 10,word SP
'write 20,word SP
'write 30,word SP
'write 40,word SP
rem _______________________________________________________

pause 2000
hsersetup B9600_16,
'hserout 0,(" PWM Battery Charger Mike Bentley")
'pause 10000
setup:
hserout 0,(124,2,50,124,0,"# VOLT SETP STATE",124,24,0,124,25,50,"1",124,24,0,124,25,40,"2",124,24,0,124,25,30,"3",124,24,0,124,25,20,"4")

lcdloop:
s_w3 = ADC1
gosub vconvert
hserout 0,(124,24,18,124,25,50)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
read 10,word SP2
s_w3 = SP2
gosub vconvert
hserout 0,(124,24,54)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
if PWR1 = 1 then
hserout 0,(" ON ")
else
hserout 0,(" OFF")

endif
if s_w4 = 10 then
hserout 0,(" *")
else
hserout 0,(" ")

endif
'pause 400

s_w3 = ADC2
gosub vconvert
hserout 0,(124,24,18,124,25,40)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
read 20,word SP2
s_w3 = SP2
gosub vconvert
hserout 0,(124,24,54)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
if PWR2 = 1 then
hserout 0,(" ON ")
else
hserout 0,(" OFF")
endif
if s_w4 = 20 then
hserout 0,(" *")
else
hserout 0,(" ")

endif
'pause 400

s_w3 = ADC3
gosub vconvert
hserout 0,(124,24,18,124,25,30)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
read 30,word SP2
s_w3 = SP2
gosub vconvert
hserout 0,(124,24,54)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
if PWR3 = 1 then
hserout 0,(" ON ")
else
hserout 0,(" OFF")
endif
if s_w4 = 30 then
hserout 0,(" *")
else
hserout 0,(" ")

endif
'pause 400

s_w3 = ADC4
gosub vconvert
hserout 0,(124,24,18,124,25,20)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
read 40,word SP2
s_w3 = SP2
gosub vconvert
hserout 0,(124,24,54)
if s_w2 > 9 then
hserout 0,(#s_w1,".",#s_w2," ")
else
hserout 0,(#s_w1,".0",#s_w2," ")
endif
if PWR4 = 1 then
hserout 0,(" ON ")
else
hserout 0,(" OFF")
endif
if s_w4 = 40 then
hserout 0,(" *")
else
hserout 0,(" ")

endif
pause 200
if s_w4 > 0 then
peek 28, word SP2
hserout 0,(124,24,18,124,25,10,"IMP ",#SP2," ")
else
hserout 0,(124,24,18,124,25,10," ")
endif
'pause 400
goto lcdloop

vconvert:
s_w1 = s_w3 * 21
s_w2 = s_w3 *25/100
s_w1 = s_w1 + s_w2/10
s_w2 = s_w1
s_w1 = s_w1/100
s_w3 = s_w1 * 100
s_w2 = s_w2 - s_w3
pause 200
return

start1:
'pause 3000
PWM1 = 1000
PWM2 = 1000
PWM3 = 1000
PWM4 = 1000
PWR1 = 1
PWR2 = 1
PWR3 = 1
PWR4 = 1
pwmout pwmdiv64,C.5,249,PWM1
pwmout pwmdiv64,C.3,249,PWM2
pwmout pwmdiv64,C.2,249,PWM3
pwmout pwmdiv64,B.1,249,PWM4

main1:
eval = 0
s_w5 = 0
s_w6 = 1000
read 10,word SP
for i = 1 to 15
readadc10 B.2,ADC
if ADC > s_w5 then
s_w5 = ADC
elseif ADC < s_w6 then
s_w6 = ADC
endif
eval = eval + ADC
next i
ADC1 = eval/15
eval = s_w5 - s_w6
if s_w4 = 10 then
poke 28, word eval
endif
'eval = eval + ADC
'next i
'ADC1 = eval/15
if SP > ADC1 then
eval = SP-ADC1
else
eval = 0
endif
if PWR1 = 0 then goto main2
if ADC1 < 200 or ADC1 > 800 or eval > 200 then
PWR1 = 0
FLT1 = 1
PWM1 = 1000
pwmduty C.5,1000
goto main2
endif
'sertxd (#PWM1,cr,lf)
if ADC1 = SP then
goto main2
endif
increase:
if ADC1 < SP then
if PWM1 > 0 then
PWM1 = PWM1 -1
endif
pwmduty C.5,PWM1
goto main2
endif
decrease:
if ADC1 > SP then
eval = ADC1 -SP
if eval > 20 then
PWM1 = PWM1 +2 max 1000
endif
PWM1 = PWM1 +1 max 1000
pwmduty C.5,PWM1
goto main2
endif

main2:
eval = 0
s_w5 = 0
s_w6 = 1000
read 20,word SP
for i = 1 to 15
readadc10 B.3,ADC
if ADC > s_w5 then
s_w5 = ADC
elseif ADC < s_w6 then
s_w6 = ADC
endif
eval = eval + ADC
next i
ADC2 = eval/15
eval = s_w5 - s_w6
if s_w4 = 20 then
poke 28, word eval
endif
'eval = eval + ADC
'next i
'ADC2 = eval/15
if SP > ADC2 then
eval = SP-ADC2
else
eval = 0
endif
if PWR2 = 0 then goto main3
if ADC2 < 200 or ADC2 > 800 or eval > 200 then
PWR2 = 0
FLT2 = 1
PWM2 = 1000
pwmduty C.3,1000
goto main3
endif
if ADC2 = SP then
goto main3
endif
increase2:
if ADC2 < SP then
if PWM2 > 0 then
PWM2 = PWM2 -1
endif
pwmduty C.3,PWM2
goto main3
endif
decrease2:
if ADC2 > SP then
eval = ADC2 -SP
if eval > 20 then
PWM2 = PWM2 +2 max 1000
endif
PWM2 = PWM2 +1 max 1000
pwmduty C.3,PWM2
goto main3
endif

main3:
eval = 0
s_w5 = 0
s_w6 = 1000
read 30,word SP
for i = 1 to 15
readadc10 B.4,ADC
if ADC > s_w5 then
s_w5 = ADC
elseif ADC < s_w6 then
s_w6 = ADC
endif
eval = eval + ADC
next i
ADC3 = eval/15
eval = s_w5 - s_w6
if s_w4 = 30 then
poke 28, word eval
endif
'eval = eval + ADC
'next i
'ADC3 = eval/15
if SP > ADC3 then
eval = SP-ADC3
else
eval = 0
endif
if PWR3 = 0 then goto main4
if ADC3 < 200 or ADC3 > 800 or eval > 200 then
PWR3 = 0
FLT3 = 1
PWM3 = 1000
pwmduty C.2,1000
goto main4
endif
if ADC3 = SP then
goto main4
endif
increase3:
if ADC3 < SP then
if PWM3 > 0 then
PWM3 = PWM3 -1
endif
pwmduty C.2,PWM3
goto main4
endif
decrease3:
if ADC3 > SP then
eval = ADC3 -SP
if eval > 20 then
PWM3 = PWM3 +2 max 1000
endif
PWM3 = PWM3 +1 max 1000
pwmduty C.2,PWM3
goto main4
endif

main4:
eval = 0
s_w5 = 0
s_w6 = 1000
read 40,word SP
for i = 1 to 15
readadc10 B.5,ADC
if ADC > s_w5 then
s_w5 = ADC
elseif ADC < s_w6 then
s_w6 = ADC
endif
eval = eval + ADC
next i
ADC4 = eval/15
eval = s_w5 - s_w6
if s_w4 = 40 then
poke 28, word eval
endif
'eval = eval + ADC
'next i
'ADC4 = eval/15
if SP > ADC4 then
eval = SP-ADC4
else
eval = 0
endif
if PWR4 = 0 then goto main1
if ADC4 < 200 or ADC4 > 800 or eval > 200 then
PWR4 = 0
FLT4 = 1
PWM4 = 1000
pwmduty B.1,1000
goto main1
endif
if ADC4 = SP then
goto main1
endif
increase4:
if ADC4 < SP then
if PWM4 > 0 then
PWM4 = PWM4 -1
endif
pwmduty B.1,PWM4
goto main1
endif
decrease4:
if ADC4 > SP then
eval = ADC4 -SP
if eval > 20 then
PWM4 = PWM4 +2 max 1000
endif
PWM4 = PWM4 +1 max 1000
pwmduty B.1,PWM4
goto main1
endif

start2:

buttonread:
if pinC.6 = 1 and pinB.0 = 0 then
s_w4 = s_w4 +10
if s_w4 = 50 then
s_w4 =0
endif
pause 300
endif

if pinC.4 = 1 and s_w4 > 0 then

read s_w4,word SP3
if SP3 < 700 then
inc SP3
write s_w4,word SP3
endif
pause 50
endif

if pinB.7 = 1 and s_w4 > 0 then

read s_w4,word SP3
if SP3 > 200 then
dec SP3
write s_w4,word SP3
endif
pause 50
endif

if pinB.0 = 1 then
select case s_w4
case 10
FLT1=0
PWR1=1
if pinC.6 = 1 then
PWM1 = 500
endif
case 20
FLT2=0
PWR2=1
if pinC.6 = 1 then
PWM2 = 500
endif
case 30
FLT3=0
PWR3=1
if pinC.6 = 1 then
PWM3 = 500
endif
case 40
FLT4=0
PWR4=1
if pinC.6 = 1 then
PWM4 = 500
endif
endselect
pause 200
endif
pause 50
goto buttonread

USB Charger

2012-08-24T00:02:00.000-04:00

Here is my USB charger that I made about 1.5 years ago. It has a bit of wear and tear on it but is still holding up. It can output over an amp of current to any USB chargeable device. The display shows voltage and current draw. It shuts off after 60 seconds automatically if no current is drawn. The screen is a .96" OLED and that is a 6V solar cell on top so it charges itself just by laying around, preferably in the sun. It has 6000 mAh of Li-poly onboard and can be charged by either solar, mini-usb or DC 6V input. It uses an LV-
BOOST, Allegro ACS713 current monitor, FET and a Picaxe 20X2. The charger board is by Sparkfun.

#no_table
#picaxe 20x2
HIGH C.5
LET adcsetup = 00000000011111
POKESFR $22,4
SYMBOL R = B0
SYMBOL G = B1
SYMBOL COLOR = W1
SYMBOL COLOR2 = W2
SYMBOL V =W3
SYMBOL VOLTS =W4
SYMBOL MA = W5
SYMBOL MAMPS =W6
SYMBOL VPOINTER = B14
SYMBOL MPOINTER = B15
SYMBOL POS = B16
SYMBOL POS2 = B17
SYMBOL POS3 = B18
SYMBOL VOLD = W13
SYMBOL VPOLD =B19
SYMBOL MOLD = W14
SYMBOL MPOLD = B20
SYMBOL U = B21
SYMBOL W = B22
SYMBOL X = B23
SYMBOL Y = B24
SYMBOL Z = B25

HIGH C.0

PAUSE 1000
HSERSETUP B38400_8, 0
HSEROUT 0, ($55)
HSERIN 0,1

HSEROUT 0, ($45)
HSERIN 0,1

R = 31
G = 0
HSEROUT 0, ($4F, $01)
HSERIN 0,1
POS = 30
HSEROUT 0, ($53, 8,0,2,0,31,1,1,"V",$00)
HSERIN 0,1
HSEROUT 0, ($53, 4,36,2,0,31,1,1,"mA",$00)
HSERIN 0,1
BARS:
W1 = B0*2048
W2 = B1*32
W1 = W1 + W2

HSEROUT 0, ($4C, POS, 0, POS, 11, B3,B2)
HSERIN 0,1
HSEROUT 0, ($4C, POS, 36, POS, 47, B3,B2)
HSERIN 0,1
INC POS
HSEROUT 0, ($4C, POS, 0, POS, 11, B3,B2)
HSERIN 0,1
HSEROUT 0, ($4C, POS, 36, POS, 47, B3,B2)
HSERIN 0,1

IF R > 0 THEN
R = R - 1
G = G + 2
POS = POS + 1
GOTO BARS
ENDIF
VOLD = 320
VPOLD =30
X = 3
Y = 2
Z = 0
MOLD = 1
MPOLD = 30
TMR3SETUP %10110001

POINTERS:
READADC10 4,V
VOLTS = V *4/10
V=V-800*100/223
V = V * 63/100 +30
VPOINTER = V
IF VOLTS < 320 THEN
VPOINTER = 29
ENDIF

IF VOLTS <> VOLD THEN
POS2 = VPOLD - 4
POS3 = VPOLD + 4
R = VPOLD - 12
IF R > 70 THEN
R =70
ENDIF
BINTOASCII VOLD,U,W,X,Y,Z
HSEROUT 0, ($47, VPOLD,13,POS2,17,POS3,17,0,0)
HSERIN 0,1
HSEROUT 0, ($53, R,19,16,0,0,1,1,X,".",Y,Z,$00)
HSERIN 0,1
ENDIF

IF VOLTS <> VOLD THEN
POS2 = VPOINTER - 4
POS3 = VPOINTER + 4
R = VPOINTER - 12
IF R > 70 THEN
R =70
ENDIF
BINTOASCII VOLTS,U,W,X,Y,Z
HSEROUT 0, ($47, VPOINTER,13,POS2,17,POS3,17,123,224)
HSERIN 0,1
HSEROUT 0, ($53, R,19,16,0,31,1,1,X,".",Y,Z,$00)
HSERIN 0,1
PAUSE 50
ENDIF

VOLD = VOLTS
VPOLD = VPOINTER

READADC10 2,MA
IF MA < 121 THEN
MA = 119
ENDIF
IF MA > 145 THEN
MA = MA*105/100
ENDIF
MAMPS = MA -119*216/10
MA=MA-119*100/46
MA = MA * 63/100 +30
MPOINTER = MA

IF MAMPS < 1 THEN
MPOINTER = 29
ENDIF

IF MAMPS <> MOLD THEN
POS2 = MPOLD - 4
POS3 = MPOLD + 4
R = MPOLD - 12
IF R > 70 THEN
R =70
ENDIF
HSEROUT 0, ($47, MPOLD,49,POS2,53,POS3,53,0,0)
HSERIN 0,1
HSEROUT 0, ($53, R,55,16,0,0,1,1,#MOLD,$00)
HSERIN 0,1
ENDIF

IF MAMPS <> MOLD THEN
POS2 = MPOINTER - 4
POS3 = MPOINTER + 4
R = MPOINTER - 12
IF R > 70 THEN
R =70
ENDIF

HSEROUT 0, ($47, MPOINTER,49,POS2,53,POS3,53,123,224)
HSERIN 0,1
HSEROUT 0, ($53, R,55,16,0,31,1,1,#MAMPS,$00)
HSERIN 0,1
ENDIF
PAUSE 5000

MOLD = MAMPS
MPOLD = MPOINTER

IF MAMPS >0 THEN
TIMER3 =0
ELSE
IF TIMER3 >240 THEN
LOW C.5
ENDIF
ENDIF

GOTO POINTERS

Battery Current Alert

2012-01-22T13:12:00.002-05:00

Here are a few pics of my battery current alert or BCA. It watches ripple currents induced by the rectifier in a VRLA or other lead acid systems to determine battery health and sets off an alarm if the ripple is too high or too low. It uses a picaxe 14M microprocessor, precision reference, precision rectifier (personal hybrid design using a ZXCT1041- see U1,C1,C2,R7-R9.) The final design replaced the dip switch bank and led shown in the drawing with 2 toggle switches and a buzzer.

symbol amps3 =W4
symbol achirp = W1
symbol in =W0
symbol n = W3
symbol n2 = W2
symbol amps = B12
symbol amps2 = W5
symbol chirp = B13

setup:
disablebod
gosub getadc
if pin1 = 1 then
amps = n
else
read 0,amps
endif
write 0,amps
if amps < 4 then
high 1
end
endif
achirp = amps
gosub ampchirp
amps2 = amps * 75/100
amps3 = amps * 125/100

main:
gosub getadc
if n < amps2 or n > amps3 then
sound 1,(60,40,80,40,60,40)
sleep 6
else
sleep 30
endif
if pin1 = 1 then
achirp =n
gosub ampchirp
pause 2000
achirp = amps2
gosub ampchirp
endif
goto main

getadc:
high 5
pause 600
n2 = 0
for n =1 to 120
readadc10 4,in
n2 =n2+in
next n
n = n2/120
'sertxd (#n," ",cr)
readadc10 0,in
sertxd (#in," ",cr)
in=51400/in * n/100
n = in
'sertxd (#n," ",cr)
n2 = 55
n = in * n2/10
n2 = in * 10/1000
n = n + n2/10
sertxd (#n,cr,lf)
low 5
n = 40 'remove this line for actual operation.
return

ampchirp:
chirp= achirp/10
if chirp > 0 then
for n2 = 1 to chirp
pulsout 1,25000
pause 150
next n2
else
gosub zero
endif
pause 2000
chirp = chirp*10
chirp = achirp - chirp
if chirp > 0 then
for n2 = 1 to chirp
pulsout 1,25000
pause 150
next n2
else
gosub zero
endif
pause 2000
return

zero:
for n2 = 1 to 3
pulsout 1,5000
pause 20
next n2
return