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G8MNY > TECH 06.07.22 09:56l 45 Lines 2119 Bytes #999 (0) @ WW
BID : 25122_GB7CIP
Read: GUEST
Subj: Fairy Light Flasher
Path: IW8PGT<IZ3LSV<IQ2LB<IR2UFV<GB7BEX<GB7CIP
Sent: 220706/0846Z @:GB7CIP.#32.GBR.EURO #:25122 [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 & capacitor timebase aided by the transistor. To work on
AC mains there is a bridge rectifier & also 2 mains filter components.
On powering the lamps are off & 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 & 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, & also diode & 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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