R2=1000 ohm 0.25w carbon film resistor
R3=1000 ohm 0.25w carbon film resistor
R4=1000 ohm 0.25w carbon film resistor
R5=330 ohm 0.25w carbon film resistor
R6=10000 ohm 0.25w carbon film resistor
R7=270 ohm 0.25w carbon film resistor
R8=470 ohm 0.25w carbon film resistor
Capacitor C1 50 volts 0.1uF non electrolytic
Capacitor C2 50 volts 0.1uF non electrolytic
Zener diode 9v1 9.1 volts
Rectifier diode2 1N4001
Rectifier diode3 1N4001
Rectifier diode4 1N4001
Led1 Red
Led2 Yellow
Led3 Green
Calculations:
Formula: Vdrop=(Rabove/Rtotal)*Vin
Vd=9.1-0.63=8.47 volts, Vin=9.1 volts, Rabove=10000 ohms
8.47=(10000/Rt)*9.1, 0.9307=10000/Rt, Rt=10743.8=10744 ohms
Rt=10744=R6+R7+R8
Rt1=R8+R7=10744-10000=744 ohm
Vd=0.63-0.23=0.4volts, Vin=0.63 volts, Rabove=R8
0.4=(R8/Rt1)*0.63, 0.6349=R8/Rt1, R8=0.6349*Rt1
Rt1*0.6349=R8
R7=Rt1-0.6349Rt1=0.3650*744=271.61=272 ohm
R7=272 ohm
R8=744-R7=744-272=472 ohm
R8-472 ohm
LEDred=(12-0.7-1.8)/9.5mA=9.5/0.0095=1000 ohm
LEDyellow=(12-0.7-0.7-1.8)/9.5mA=8.8/0.0095=926 ohm
LEDgreen=(12-0.7-1.8)/9.5mA=9.5/0.0095=1000 ohm
R5=V5/I5
V5=12-0.7-9.1=2.2 volts
I5=Izener+ItoR6
ItoR6=9.1/10000=0.00091 amps
Izener=5.6mA=0.0056 amps
I5=0.0056+0.00091=0.00651 amps
R5=2.2/0.00651=337.9 ohm
Problems:
This is the third circuit i have done and i have struggle with calculation a little bit, but circuit design and lay out was 100% from first try without any mistakes.
Test procedure:
Voltage drop at 0.7 volts signal input across:
Diode 01=0.71 volts - knee voltage that diode need to work.
Capacitor 01=12.21 volts - fully charged capacitor to available voltage.
Resistor 04=2.9 volts
Capacitor 02=9.32 volts Fully charged capacitor to zener diode reverse bias voltage.
Zener diode 01=9.32 volts - as it installed in reverse bias it take's that to push electrons through.
Resistor 06=8.68 volts - its how much voltage restricted by the resistor.
LED red=2.04 volts- shows that LED lighted as inverting voltage of opam greater then non-inverting , so in out put its inverted and amplified.
Resistor 03=8.94 volts
Resistor 08=0.41 volts
Resistor 07=0.23 volts
Resistor 02=6.39 volts
LED yellow=0.01 volts
Diode 04=0.06 volts
LED green=1.59 volts
Explanation:
The circuit i build is an oxygen sensor tester. Its This is potential divider circuit, that means its divided onto three regions and depending on the oxygen sensor signal it should light up one of the LED for each region which was set up with different resistors. Three regions are Lean-green LED from 0-0.23 volts, Normal-yellow LED from 0.23-0.63 volts, Rich-red LED 0.63-0.99 volts. If connect it to a vehicle oxygen sensor, on idle speed it will blink forward and back through all LEDs as oxygen sensor constantly adjust fuel mixture. At the acceleration Rich-red LED will light up and at deceleration it will light up Lean-green LED.
Reflection:
After inspecting my circuit few times i found something that i can upgrade to make it better. First i made 4 joints with white wire for oxygen sensor input signal, this could be done only with 1 jumper wire if wouldn't cut tracks between opams legs 3 and 12, 6 and 10 and just put jumper wire across 3 and 6, in this case all 4 legs can be connected with only one wire.
