■ FIGURE 6
Last month, Figures 6 and 7 (solar power supply) were inadvertently left out of the layout. They
are reprinted here for your convenience and are also available at www.nutsvolts.com.
90 VOLT SUPPLY PARTS LIST
■ FIGURE 7; October ’08 issue
PART
■ IC1
■ IC2
■ Q1
■ D1
■ LED1
■ R1
■ R2
■ R3
■ R4
■ R5
■ R6
■ R7
■ R8
■ C1, C2
■ C3
■ C4
■ T1 Core
■ T1 Bobbin
■ Battery
■ Solar Panel
DESCRIPTION P/N
NE556 dual timer 595-NE556N
LM393 dual comparator 511-LM393N
NMOS, 100V, 0.45A, logic level 522-ZVN4210A
400V, 1A, 50 ns, DO- 41 821-1N4936
Red 156954
13.3K, 1/8W, 1% 270-13.3K-RC
1.0K, 1/8W, 1% 270-1K-RC
6.81K, 1/8W, 1% 270-6.81K-RC
100Ω, 1/8W, 1% 270-100-RC
10Ω, 1/8W, 5% 270-10-RC
1M, 1/8W, 1% 270-1.0M-RC
10K, 1/8W, 1% 270-10K-RC
10K trimpot 652-3296Y-1-103LF
1,000 pF, 50V, NPO 81-RPE5C1H102J2P1A03
0.1 µF, 50V, X7R 81RPER71H104K2P1A03
0.1 µF, 200V, film 80-R821C3100DQ60J
F-42510-EC
B2510-10
6V gel cell, 1.3 Ah
4.5V/90 mA, 2 3/8” square
SUPPLIER
Mouser
Mouser
Mouser
Mouser
Jameco
Mouser
Mouser
Mouser
Mouser
Mouser
Mouser
Mouser
Mouser
Mouser
Mouser
Mouser
Magnetics
Magnetics
Mouser
BG Micro
type with two 15 volt
windings to give a 1:1
ratio. A 240/24 volt
transformer should work
also. It is all in a securely
fastened plastic box. Also,
because the mains voltage
in the US is 120 VAC,
the resistor R4 is 620
ohms, 5W.
Dimmer for 12 VDC
Lamps
QI have a small
pop-up camper
with two sets of
dual lamp light
fixtures in it. There is only a single
on/off switch. I would like to build a
couple of dimmers for these fixtures. I
think I can do this the easiest with a
circuit similar to a switching power
supply. What are your thoughts and
ideas for a circuit?
— Tom Bohacek
632-GH613
PWR1241
AIt is only necessary to chop
the 12 volts; 12 volt lamps
are normally 40 watts and
there are two of them so
the current to be chopped is: I = P/E
= 80/12 = 6. 7 amps. A 556 IC driving
a MOSFET is the circuit; see Figure 6.
The frequency only needs to be high
enough that you don’t see the flicker,
so 100 Hz will work. The first 555
is an astable and provides the
frequency. The second 555 is a one
■ FIGURE 6;
October ’08 issue
30
November 2008