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G8MNY > TECH 29.01.90 11:30l 45 Lines 2131 Bytes #999 (0) @ WW
BID : 50904_GB7CIP
Subj: Fairy Light Flasher
Path: IZ3LSV<IW8PGT<LU4ECL<LU1DBQ<VK6ZRT<GB7CIP
Sent: 260129/1020Z @:GB7CIP.#32.GBR.EURO #:50904 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Feb 10)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
This is a simple design used to flash a low power mains Christmas tree fairy
light set. The unit is in the shape of a bell & plugs in instead of a lamp.
CIRCUIT
5x 1N4007ÚÄÄÄÂÄÄÄÂÄÄÄÄÄÄÄÂÄÄÄÄÄÄ¿
_³_ _³_ _³_ ³ ³
/_\ /_\ /_\ 100K ³ ÞÝ
³ ³ ³ Disc ³Charge³ _±±_
LÄÄFuse-bulbsÄ<<ÄÄÂÄ100RÄ´ ³ 20K ³ ³ /~ ~\
Bulb === ³ ³ ÃÄÄÄÄÄÄÄ´ ³ Þ Ý
u1 ³ ³ ³ ³ 62K ³ ³ PCB ³
400V³ ³ ³ ³ ³ ³ ³³ ³³
)|| ³ ³ ³ _³_Neon ³ ݳ ³Þ
)||L ³ ³ ³ /_³_\ ³ Þ ³ ³ Ý
)|| ³ ³ ³ (ù___ ) ³ / ÀÄÄÄÄÄÄÙ \
NÄÄÄÄÄÄÄÄÄÄÄÄÄ<<ÄÄÁÄÄÄÄÄÄ)ÄÄÄ´ +³ \_³_/ ³
_³_ _³_ === ³ ³/
/_\ /_\ ³10u ÃÄÄÄÄ´ 2SC106D
³ ³ ³160V 20K ³\e NPN
ÀÄÄÄÁÄÄÄÁÄÄÄÄÄÄÄÁÄÄÄÄÄÄÙ
HOW IT WORKS
This basically a neon and capacitor timebase aided by the transistor. To work on
AC mains there is a bridge rectifier and also 2 mains filter components.
On powering the lamps are off and the 10uF charges up via the 100K (off time).
When it has reached the neon striking voltage (85V) current flows through the
neon to the transistor base. The transistor conducts and shorts out the flasher
supply making the lamps some on. The transistor stays on until the neon goes
out @ about 70V from the 10uF. The on time is determined by the discharge
through the 62K+neon, and also diode and 20K route.
The other 20K ensured the transistor is kept properly off when the neon is out.
See my TECH bul on "Christmas Mains Light Chains" & "Night Light Switch"
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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