Circuit no.2 and no.3

lochmaster draw up

circuit no.3
components:

d1 = 9v1 zener diode IzRm 5.6 mA

d2, d3, d4 = 1N4001 type diode

c1, c2 = 0.1 uf capacitors

r2, r3, r4 = 1000 ohms .25w

r5 = 390 ohms .25w

r6 = 10k ohms .25w

r7 = 330 0ohms .25w

r8 = 660 ohms .25w

led d1 (red), d1(yellow), d2(green) =1.8v 9.5 mA

ic1 = operational amplifer lm324

working :

r2,r3,r4 = 1k ohm resistors
r5 = 2.2v/0.00645A = 341.24 ohms, use of 390 ohms

r6 = given resistance of 10k ohms

r7 = 0.23v/0.000847A = 271.34ohms, use of 330 ohms

r8 = 0.4v/0.000847A =472.25 ohms

Explantion:

when testing circuit no.3 , the board made a zapping sound, later testing the board finding that the op- amp short circuited, after looking careful it was because of a soldering problem conecting two tracks of the op- amp together.

circuit no 2

Components:

3X resistors,
R1=800 ohm

R2=330 ohm

R3=1k ohm
2x capactors
2x diodes

1x zener diode
1x led 1.8v 40ma

1 LM317 transistor

working
vref=1.25............vout=5v

vout =vref(1+r3/r2)

5=1.25(1+r3/r2)

5/1.25(1+r3/r2)

4=1+r3/r2

4-1=r3/r2
3=r3/r2

990/330

3-1 ratio

3=990 ohms ...R2=330 ohms

NOTE:
as the resistor does not exict im using a 1k ohm resistor

R1 resistor before the 1.8v LED: R =v/i 5-1.8v /0.004 = 800 ohms using 1k ohm

Explantion:

starting with D13 the supply voltage enters. In parallel is a zener diode, with a capactor, these two are then earthed to ground ,
R2 330 ohm and R3 990 ohm help the voltage regulator LM317 convert the voltage to a lower level of 5v .R1 1k ohm is in series with the LED 1.8v also being ground to earth.

actual circuit

Reflection and results:

Vout=Vref

v=1.25v

VD across the output leg of the regulator to earth was 5.03v

accpectable as the supply to output is 5v

VD across the LED is 1.92v

also alright as led has a spec of 1.8v

R1 VD is 3.11v

also fine as 3.11v+1.92v=5.03v