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G8MNY > TECH 01.03.22 09:15l 51 Lines 2117 Bytes #999 (0) @ WW
BID : 61851_GB7CIP
Read: GUEST
Subj: Thermostatic Soldering Iron LED
Path: IW8PGT<IZ3LSV<IQ2LB<IR2UFV<SK0BO<SM0YOS<GB7CIP
Sent: 220301/0803Z @:GB7CIP.#32.GBR.EURO #:61851 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Mar 11)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
This circuit is suitable "Magnetic Curie Point" temperature switch controlled
mains irons! The LED lights up when the Iron is plugged in & is drawing current
in its heat cycle it goes out when it is up to temperature. It also works on
some internally electronic controlled 24V irons too.
Also shown is a static earth, that keeps the stray tip voltage down to about
12V AC MAX, while still giving an "un earthed iron" for work on live circuits
(~100V) safely.
CIRCUIT
Fuse ON
LÄo-oÄÄÄÄo\oÄÄÄÄÄÄÄÄ¿ Temp
250mA )|| ÚÄÄÄÄÄÂÄÄÄoÄÄÄÄÄÄÄÄÄÄo_oÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
LED )||( 10k Switch Curie ³
ÚÄ´<ÃÄ¿ 230V)||(24V ÚÄ´ :...Magnet Iron 12R Element
³ ³ )||( ³10k Bit 48W
ÃÄ´>ÃÄ´ )|| ÀÄÄÄ)ÄÁÄÄÄoÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
NÄÄÄÄ´ ÃÄÄÄÄÄÄÄÄÙ ³ ³-----------------------------iron earth
ÀÄ33RÄÙ ³ 1M If 3 wire
EÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÙ
Á
The LED is connected to the mains neutral, but even so good insulation is
needed! The bypass diode connected the reverse way is a 1N4001 & stop mains
reverse voltage appearing across the LED. The value of 33R is selected so that
the LED is not lite with just the transformer magnetising current.
If the 50Hz flashing LED is anoying, blows up the LED, or is not bright enough
try this more complex circuit instead...
LED
ÚÄ´<ÃÂÄ´<ÃÄ´<ÃÄ¿
³ ³100u+³ ³ Here the 27R is selected for brightness & unlit LED
ÄÄ´ ÃÄÄ´ÃÄ´ ÃÄÄ when the iron is not on. The 100uF protects the LED
ô>ÃÄ)ÄÄÄÄÄÙ ³ from some of spikes in mains power surges as well as
³ ÀÄÄÄÄÄÄ´>ÃÄ´ reducing the 100Hz LED flicker. Diodes are all 1N4001.
ÀÄ27RÄÄÄÄÄÄÄÄÄÄÄÙ
Also see my Tech Bul on "Soldering Iron Economiser/Boost"
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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