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Lights for scale boats

J

JSchermeis

Jan 1, 1970
0
Help! I build radio controlled scale ships and boats as a hobby and need a
circuit to operate the lights. Depending on the model, the main power is
between 6 & 12v dc. I'm using 1.5v, 30mA bulbs, and need from 5 to 15 lights
per model. The lights should operate at 1.3v for longer life and authentic
appearance. I don't read schematics that well and have even less of a clue how
to use it to make the finished circuit. But I could use about 10 of these in
my projects. Any ideas?
John
 
J

Joe McElvenney

Jan 1, 1970
0
Hi,
Help! I build radio controlled scale ships and boats as a hobby and need a
circuit to operate the lights. Depending on the model, the main power is
between 6 & 12v dc. I'm using 1.5v, 30mA bulbs, and need from 5 to 15 lights
per model. The lights should operate at 1.3v for longer life and authentic
appearance. I don't read schematics that well and have even less of a clue how
to use it to make the finished circuit. But I could use about 10 of these in
my projects. Any ideas?


Why not try something like this? (View in Courier)!

-----
O ----|78L05|-----------------------
----- | | |
| (x) (x) (x)
| | | |
| (x) (x) (x)
7-12V DC | | | |
| (x) (x) (x)
| | | |
| (x) (x) (x)
| | | |
O-----------------------------------

The x's are lamps and the 78L05 is a small 5V regulator that should be
available from any electronics hobby shop. This will give you 1.25V per lamp and
will take up any slack should you use a variety of supply voltages. You could use
the 1A capacity 7805 instead without a heatsink as you will be drawing less than
100mA. In fact, if you have the room, I would use the 7805 anyway.


Cheers - Joe
 
R

Rich Grise

Jan 1, 1970
0
Yes, I was about to suggest the same thing, except without the
regulator. On a battery-powered boat, I'd think that you don't
want to throw away any watts (which is what a regulator does) -
just put the right number of bulbs in series for either a 6V
or 12V system. I certainly wouldn't put in a universal light
string, because once you've picked a battery for a given
boat, it probably won't change.

I'd also go for more than 1.3 as a target bulb voltage - it's
amazing how much difference in light output there is for a
very small change in voltage near its operating area. Say,
1.4 ~ 1.45V. The important part, of course, is the current
flow. John presumably knows to use matched bulbs, of course. :)

The simplest thing would be to put 4 or 5 in series for a 6V
system, and see which looks best, and 8 or 9 in series for a
12V system. If you really want to fine-tune it, you could
interpose some smaller resistance in series - even something
like a car bulb - it wouldn't light, but it'd drop the voltage
a little, so the bulbs will last longer.

Good Luck!
Rich
 
W

Watson A.Name - Watt Sun

Jan 1, 1970
0
Help! I build radio controlled scale ships and boats as a hobby and need a
circuit to operate the lights. Depending on the model, the main power is
between 6 & 12v dc. I'm using 1.5v, 30mA bulbs, and need from 5 to 15 lights
per model. The lights should operate at 1.3v for longer life and authentic
appearance. I don't read schematics that well and have even less of a clue how
to use it to make the finished circuit. But I could use about 10 of these in
my projects. Any ideas?
John

An LM317 will give you 1.2V with the adj pin grounded, and if you use
the regular 3 resistor circuit, any voltage above that up to its
maximum.


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