On Wed, 13 May 2020 13:48:11 -0400, Paul
wrote:

AnthonyL wrote:
I have an old battery (6 x D cells) torch which has a fluorescent
tube, a spotlight and a flashing light behind a red (plastic) glass.

The torch also has a DC power input of unspecified voltage which then
runs into some circuitry.

1) The battery compartment has got corrosion, half of a spring has
gone (there are two springs at the bottom, one for each set of 3
batteries), but there is continuity between the spring connections. I
plan to take a spring off a defunct 6v lantern battery to replace the
damaged spring. What would be the best way to fix it?

2) The fluorescent tube is a Sylvania White F6W/W which has probably
been superseded. 210mm x 16mm. Grey/black at one end. Is there
anyway to test if this works outside of the torch?

3) I've put a 9v supply into the torch and at least the spotlight
functions though nothing else. All the connections appear to be
accessible. What should I be measuring for the fluorescent tube?

Whilst this is one of numerous "Covid" projects I have on the go are
modern LED torches a better bet? Though I don't like the light from
my head torch or even any that I've put into lamps


Tubes work best with sine wave (AC) drive. In this example
web page, the "working" voltage listed for the tube is 70V.

https://www.electroschematics.com/fl...t-lamp-driver/

"After start, the voltage collapses from several hundred volts
to the operating voltage, which is ca 70V for an 8W rod."

It's highly likely there is an inverter of some sort, inside
the plastic housing. And with any luck, glued plastic pieces
to keep you out.

"Pure flyback single-transistor inverter, makes voltage spikes
in the kilovolt range in idling condition, so that the lamp
will start. Disadvantage: One filament evaporates and blackens
the lamp, makes it electrically unsymmetric and shortens the lifetime."



Well I can get to the connections that the tube fits in. So with
power connected I should get an AC voltage reading with my
multi-meter?


--
AnthonyL

Why do scientists need to BELIEVE in anything?