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G8MNY > TECH 10.07.26 09:33l 35 Lines 1757 Bytes #999 (0) @ WW
BID : 64573_GB7CIP
Read: OE5RCO DJ6UX GUEST
Subj: LED as a mains NEON
Path: DB0FHN<DB0RKB<DK0WUE<IW2OHX<GB7OSW<GB7BED<N2MH4<N3HYM<K5DAT<VK3AT<
VK7AX
Sent: 260710/0713Z 14039@VK7AX.#ULV.TAS.AUS.AUNZ Linor 850, Terminal Font)
Neon lamps that run too brightly usually don't last long as the glass blackens
with electrode metal. To replace the neon does not cost much if you have a
source of them. But to replace the whole thing for an LED with a bridge
rectifier & a suitable mains capacitor & surge R is far more expensive..
ORIGINAL SIMPLE REPLACEMENT BETTER COMPLEX REPLACEMENT
1mA 20mA 10mA u15 10mA
LÄÄ180KÄÄÄÄ¿ ÄÄ12KÄÄÂÄÄÄ¿ Ä12KÄ´>ÃÂÄÄÄ¿ ÄÄ1KÄÄÄ´ÃÄÄÄÄÂÄÄÄÄÄÄÄÄÄ¿
1/4W ,-³-, 5W ³ ³ 3W ³ ³ 1/4W (X=20k)_³_ _³_
/ ÄÁÄ \ _³_ _³_ _³_ _³_ (@50Hz) /_\ LED \_/
80V | o | LED <-\_/ /_\ <-\_/ /_\ ÃÄÄÄ´<ÃÄÄÄ´
NEON \ ÄÂÄ / 1.5V <- ³ ³ ³ ³ _³_ 10mA _³_
`-³-' 10mA³ ³ 10mA ³ ³ \_/ /_\
NÄÄÄÄÄÄÄÄÄÄÙ ÄÄÄÄÄÄÄÁÄÄÄÙ ÄÄÄÄÄÄÄÄÁÄÄÄÙ ÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÙ
Power = 0.24 W 4.8 W 2.4W 0.4 W
Flicker = 100Hz 50Hz 50Hz 100Hz
The Neon has 80V drop & to give reasoz flicker.
Adding a high voltage series diode in the arrangement halves the power, but
will add DC component to the supply & also it may cause more QRM. 50Hz flicker.
Using a mains AC capacitor as the current dropper, due to it's impedance makes
for a more efficient if complex arrangement, but still a spike current limiting
R is needed as well. Using a bridge rectifier also doubles the current into the
LED, making it more efficient. The C needs to be about 0.15uF @250V AC with a
surge R (fuse type) of say 1K. 100Hz flicker.
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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