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ZX Hard #00
31 августа 1998 |
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Measurements - a very useful shemka for testing printed circuit boards.
Measurements.
(R) VTS'98
(C) an engineer A. Belousov, YUT'1 / 86.
Now I draw a very useful
shemku for testing printed circuit boards from
magazine UT (Junior Technician), 1 / 86 ".
In parentheses are given ratings for the supply of +5 V (the
original - +3 V).
R1 R2 R3 R4 R5 VD2
>
about
\ / R7 +3 (5) v
e e gnd
VT1, 2 R6 / about
<> \>
Probes VD1 e
<
VT3
VT1 ... 3 - KT315, VD1 - D9, VD2 - AL307
R1 - 300 (510), R2, 4 - 5.1k, R3 - 51k,
R5 - 3k (5.1k), R6 - 100, R7 - 100 (300).
Principle: if the resistance
between the probes (Rx) of less than 10 ohms, the LED lights.
This allows you to check the track for an open or a closure.
Because of the low test voltage, limited diode VD1 (about 0.3v),
all the transitions n / n devices on the board will
locked (R>> 10th), also in a thin
equipment no resistor below the 10th (the exception - Coil /
Choke) that can be used to probe
'Stuffed' board, and for repairs, but the circuit should be
deenergized!
When testing large capacitors probe will give a unit impulse and
damped (aka - kondyuk samples).
3lementy R1, Rx, R5, R6 form a measuring bridge, in which the
diagonal includes a comparator for VT1, 2. At VT3 collected for
the indicator buffer (VD2).
Acts, I must say, not bad. Before
I always had to look at the tester. It will be necessary to
attach a sound ;-). (To the next number).
12.08.98 00:01 msk is-dos
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