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G8MNY > TECH 07.02.23 11:56l 182 Lines 8987 Bytes #999 (0) @ WW
BID : 40094_GB7CIP
Read: GUEST
Subj: 12V Fluorescent Tube Inverters
Path: IW8PGT<LU4ECL<LU9DCE<VA3TOK<VE3KPG<GB7CIP
Sent: 230207/0800Z @:GB7CIP.#32.GBR.EURO #:40094 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Here are 2 designs:-
From Chrissi ZR6CBP
Very Easy Fluorescent Tube Inverter Circuit 12V DC to 220V AC 6 Ä 20 W
(corrected by G8MNY 08/06)
+ 12 V
ÚÄÄÄÄÄÄÄÄÄÄÂÄÄÂÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³³ ÚÄÄÄÄÄÄÄÄ¿
10K ³ ³ ³ ³³ / ³³
³ 555ÚÄÄÁÄÄÁ¿ / ³³ \ ÚÁÁ¿
ÃÄÄÄÄÄÄÄ´7 8 4³ 12V \ ³³ / 220V ³ ³
\ ³ ³ 1A / ³³ \ ³ ³
1M /<ÄÄÂÄÄÄ´6 ³ \ ³³ / ³ ³
\ ³ ³ ³ / ³³ \ ÀÂÂÙ
ÃÄÄÄ´2 3ÃÄÄÄ¿ c³ ³³ / ³³
0.1Ä ³ ³ ³ / b ³/ ³³ ÀÄÄÄÄÄÄÄÄÁÙ
0.001 === ³ ³ \<ÄÄ100RÄÄÄÄÄÄ´
³ ³ 5 1 ³ / R TIP ³\
³ ÀÄÂÄÄÂÄÙ \ 4K7 41 e³
³ .01=== ³ ³ ³
ÀÄÄÄÄÄÁÄÄÁÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
(Modification from Eric ON4CBL)
Tune 1M for +Ä 10 kHz, & maximum efficiency / resonance from transformer.
Tune 4k7 for desired current / brightness.
Heatsink TIP 41 for currents > 300 mA.
----------------------------------------------------------------------------
From : VK3EUB.#MEL.VIC.AUS.OC (Brian)
This circuit appeared in silicon chip mag October 1999 page 75
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ 6 T ÀÄ¿ ³ ÚÄÙ ÚÁ¿
³ feedback Ä´ ³ ÃÄ ÚÅÄÅ¿
³ ÚÄÙ ³ ÃÄ ³ÀÄÙ³
safety ³ ÚÄÄÄÄÄÄÄÄÄÄÙ ³ ÃÄ 960 T ³ ³
resistor ³ ³ ³ ÃÄ secondary ³ ³
+12VÄÄÄÄÄÄÄ´ 3R ÃÄÄÄÂÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ ÃÄ ³ ³
³ ÚÁ¿³ ³ 20 T ÀÄ¿ ³ ÃÄ ³ÚÄ¿³
³ ³ ³³470R ³ primary Ä´ ³ ÃÄ ÀÅÄÅÙ
100æF + ³ ÀÂÙ³ ³ ÚÄÙ ³ ÀÄ¿ ÀÂÙ
16 VW ÄÁÄ ÃÄÙ ³ b ÃÄÙc ÀÄÄÄÄÄÄÄÄÄÄÄÄÙ
ÄÂÄ ³ ÃÄÄÄÄÄÄÄÄ´ 15W or 18W
Ä ³ ÄÁÄ ÄÁÄ Ã>¿e BD681 fluorescent
³ ÄÂÄ ÄÂÄ ³ tube
³ ³0.0012 ³0.022 ³
0VÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÁÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÙ
This fluorescent light inverter uses just one transistor & a transformer wound
on a ferrite rod. The clever component is the transformer, it performs 3
functions. Firstly, it acts as a feedback component for the transistor to
create an oscillator circuit. Secondly, it provides a high voltage (over 2kV)
to strike the fluorescent tube & thirdly it supplies energy to keep the tube
illuminated.
The transformer has 3 windings. The 20 turn primary is switched by the BD681 &
the resulting primary voltage of around 24V peak to peak (plus considerable
spikes) is stepped up in the 960 turn secondary. Positive feedback is applied
from the third winding to the base of the BD681 to ensure that the circuit
oscillates continuously.
The ferrite core of the transformer is an antenna rod from a transistor radio.
You can use a slab antenna but i chose to use an antenna rod 6cm long & 9mm in
diameter.
The primary winding is the first to be wound, on 45mm of the rod, using 20
turns of 0.5mm diameter enamelled copper wire. Use grease-proof paper as the
interlayer insulation. The second winding is the feedback winding & consists of
6 turns of 0.3mm wire wound in a spiral fashion so that it lies over the full
length of the primary winding.
The secondary winding consists of 960 turns of the 0.3mm wire. The feedback
winding must be connected the right way around so that the BD681 gets positive
feedback. When first powered up, connect the 3ê safety resistor in the positive
line & connect the feedback winding. Then turn the circuit on & off very
quickly & if the fluorescent tube does not come on immediately, the feedback
winding is the wrong way around. The safety resistor allows a limited current
to flow through the circuit & the BD681 will not be damaged.
Once the correct feedback connection has been established & the fluorescent
light comes on correctly, remove the 3R resistor & the circuit is ready to
use. However, you must not use the circuit without the fluorescent tube
connected because it provides loading for the transformer & has a damping
SB TECH @ WW
12V RF immune AF Booster Amp
By G8MNY (Updated Mar 08)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
This is a simple AF 5W booster amp for handhelds etc. I built mine into a large
RF PA box & included a 5" LS so it is really loud. It has the advantage of
being fairly RF immune unlike IC Amplifiers. Handhelds & small rigs don't
produce a full power rail LS swing (often on low voltage) so a small 2:1 step
up transformer is used to make sure the double emitter follower current gain
circuit can go into full clipping with low drive swing. Using a low 4ê or 3ê LS
plenty of AF power is available.
ÚÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄoÄÄoÄ<+12V
C1 47uF 1K ³ ³+ 3A
Rig LS>ÄÂÄÄ´ÃÄÄÄÂÄÄÄ¿ 220uF ³ TR2³/ C6 === 470uF
³ + )º(ù ÚÄÄÄ´ÃÄÄÄÄÁÄÄÂÄÄÄ´ NPN ³ 18V
³ 2x )º( ³ C3 + _³_ ³\e + 1000uF ³
³ Step )º( ³ D1 \_/ ÃÄÄÄÄ´ÃÄÄ¿ 10V ³
100ê up ù)º(___³ C4 + ³ ³/e C5 ³ ³
³ T1 ³ ³ ÀÄÄÄ´ÃÄÄÄÄÂÄÄÁÄÄÄ´ PNP ÚÁ¿/³4R ³
³ ³ === 220uF ³ TR1³\ ÀÂÙ\³LS ³
³ ³ C2³SOT 10V 1K Ge ³ ³ 8W ³
ÄÄÄÄÄÁÄÄÄÄÄÄÄÁÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄ-< -ve
INPUT CIRCUIT
The input 100ohm is only there to provide a DC path if the rig needs a DC load
for bootstrap current etc. It can be omitted to save handheld battery life if
this is not required.
The input load on the handheld will be the 1/4x (LS x HFE // 500ohm) which
should be no lower than 15ohm.
T1 is typically a small transistor radio output transformer of 50mW or so
rating, that has 2 identical windings. This ensures the Transistors will be
driven with voltage swings above & below the power rails for max power.
_
+4V_ _ +12V~³ / \ /~\
³/ \ ³³ ³ ³ ³
_³ \_/ ³ ³ ³ ³ ³
-4V 50mW 0V_³ \ / \_/
Input Base ~ Drive Full Swing
> 0 & 12V Output 5W
The value of C1 limits the LF response, & with the inductance of T1 plus the
input load can give a good LF cut off below 300Hz of a rate of 12dB/Octave.
C1 only needs to be low voltage type.
6dB/O LF cut 6dB/O HF cut
Ä´ÃÄÄÂÄÄÄ>to LOAD ÄÄ((()ÄÄÂÄÄ>to Load
C1 )º ==== ³
L )º Another L === Another
)º 6dB/O C2 ³ 6dB/O
ÄÄÄÄÄÁÄÄÄ ÄÄÄÄÄÄÄÄÁÄÄÄ
Gain
0¿ .ÄÄÄÄÄÄÄÄÄÄÄÄÄÄ.
-3dB´ / \
³ / \
-12dB´ / \
ÃÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÄÂÄÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄ¿ Hz
0 80 150 300 700 1k5 3k 6k 12k
The value of C2 is best found on test (SOT), it's effect together with the non
mutual inductance leakage L of T1 provide a sharp HF cut off point above 3kHz &
also gives a slope of 12dB/Octave. Typical C2 Value is 1nF.
BIASING
A single Silicon diode D1 is used with 2x 1k to give the required 0.7V bias @
half power rail point. To maintain the bias over the input current drive cycle
2 large capacitors C3 & 4 are used. These only need to be 10V working.
TRANSISTORS
Use a metal box for the construction & bolt down TR1, a PNP Germanium
transistor like a TO3 OC35, with no insulation kit, & TR2 a Silicon NPN like a
2N3055 with an insulation kit. As these are a double emitter follower output,
then the bias voltage of 0.7V is just about right, so no emitter Rs are needed.
As there is 100% NFB the distortion is low even with non gain matched devices,
but there will be some low level crossover distortion!
OUTPUT
This is fed through a large C5 1000uF to maintain the low output Z & low
losses. Unlike IC amplifiers were the peak LS voltage is typically ñ1V less
than the power rails, in this design it will be very close to full power rails.
So quite a bit more power is available. e.g. on 14V it should give ñ6.8V swing
into 4ê giving about 5.8W RMS 11.6W "USA music rating" (e.g. full square wave
power.)
For stability C6 is included across the power rails.
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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