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Continuous feed source of 14VO-68
By YO6QCZ
The confection ideea of this source came from the feeding necessity of some devices (like: clock ,
economic light bulb at 12 V , radio stations) because of the lack of electric stream, on a definite limited
time period (depends on the bettery capacity).
I've chosen the usage of a slug (Pb) battery with 12V ­ 7 Ah tight acid (used in a lot of industrial
schemes, like : alarms, opening door latches, etc).
I've thought for a scheme with the automatic charge possibility of the battery from the 220V network by
the instrumentality of a redressor­transformer and of a 555 tip circuit with the possibility of tuning the
charging lintels (up) and (down) with the help of some semi­adjustable.
The charging I is given by the R4 resistance, which is arround the value of 0,2 A. The pieces are
mounted on a lay with the exception of the transformer, of the fuse on the battery and of the LED diodes
which signalls the state of device.
Diode (LED1) signalls that the device is conectet to the 220V network.
Diode (LED2) signalls the voltage presence to the vent + 13V
Diode (LED3) signalls that the battery is charging ; This diode turns on and off automatically at an
interval of approximate 30 seconds ­ based on the voltage tunings ­ the upper lintel and the lower lintel ­
of the semi­adjustables. The scheme is functioning from the start, but the two lintel semi­adjustable
must be adjusted.
Stuffs list
TR 1 ­ 220/15V ­ 1 A
P1 = B100C1500R
Z1 ­ DZ10V
T1 ­ BC171C
T2 ­ BD238
C.I. ­ NE555
S1,S2 ­ semi­adjustable 0,5W ­ 10K
Sig 1 ­ 1A
Sig 2 ­ 4A
R1 ­ 330Ω 10,5 W
R2 ­ 1K 10,5W
R3 ­ 330Ω 10,5W
R4 ­ 24Ω 2W
R5 ­ 6K ­ 0,5W
R6 ­ 18K ­ 0,5 W
R7 – 220 Ω
R8 – 1K Ω
R9 – 2 K2
Accum = 12V / 7 Ah
S1 ­ it adjusts for U max = 14,2 V
S2 ­ it adjusts for U min = 13,4 V
Once made this two adjustments, the device is functional .
I wish you : Success !
Y06QCZ ­ Dorin
[ HAM­MAG N.14 March 2010 ]