| |
G8MNY > TECH 10.07.06 09:10l 65 Lines 2666 Bytes #999 (0) @ WW
BID : 37742_GB7CIP
Read: DL1LCA GUEST
Subj: Volt Indicator Screwdriver
Path: DB0FHN<DB0RGB<DB0SL<DB0FSG<DB0GAP<DB0KFB<DB0CZ<F6KFG<DB0GE<DB0LJ<
DB0RES<DK0WUE<I0TVL<CX2SA<GB7YFS<GB7CIP
Sent: 060709/2342Z @:GB7CIP.#32.GBR.EU #:37742 [Caterham] $:37742_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (NEW Sept 2004)
(8 Bit ASCII Graphics use code page 437 or 850)
This is the circuit of a 1 screwdriver voltage tester...
ROLSTON's ORIGINAL VOLTMETER SCREWDRIVER
______________________________________
³com L C D ³
³ 220V 110V 55V 36V 12V ~ ³
DIRECT Ą-Ā-----Ā-----Ā-----Ā-----Ā-----Ā----Ā-Ł<- Conductive Mats
TEST ³ ³ ³ ³ ³ ³ ³
ŪŪÄ22MÄÄ22MÄĮÄM92ÄĮÄM91ÄĮÄ1M2ÄĮÄ2M7ÄĮÄ10MÄĮÄÄÄÄ)ÄÄÄÄÄĀÄ=======>SCREWDRIVER
³ NEON
ŪŪÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĮÄ2M7ÄŁ
INDUCTIVE
BREAK TEST
DIRECT TEST
If you have not seen one of these, they have a small LCD panel in the
flattened black handle that indicates if the voltage is greater than the
displayed graphics. This occurs when any of the LCD sections sees greater than
about 1V. As the LCD current required for any of the display sections is only
the odd pA very high value resistors can be used to make up the multiplier
chain. This means the return circuit can safely be made though ones finger to
earth.
INDUCTIVE BREAK TEST
A neon is also fitted for a Inductive Break-point Test. (what ever that is)
It lights when voltages are above 80V, above 2V you just see the ~ symbol.
N.B. with this circuit, this test is not too safe, as current COULD flow
through the LCD to you! So I don't recommended you use the neon option as a
mains tester!
G8MNY's MODIFIED VERSION
To open the unit to improve the calibration & modify etc, pop out the back
panel cover & ...
1/ Change one of the 22M to a 10M (100v) to increase the sensitivity on DC.
2/ Then add a 270pF (20v) cap to reduce the sensitivity on AC.
3/ Add a 220K (250v) into the inductive break test circuit.
______________________________________
³com L C D ³
³ 220V 110V 55V 36V 12V ~ ³
DIRECT Ą-Ā-----Ā-----Ā-----Ā-----Ā-----Ā----Ā-Ł<- Conductive Mat
TEST ³ ³ ³ ³ ³ ³ ³
ŪŪÄ22MÄÄ10MÄĀĮÄM92ÄĮÄM91ÄĮÄ1M2ÄĮÄ2M7ÄĮÄ10MÄĮĀÄÄÄ)ÄÄÄÄÄĀÄ=======>SCREWDRIVER
ĄÄÄÄÄÄÄÄÄÄÄÄÄ“ĆÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄŁ ³ NEON
270pF ³ ³
ŪŪÄÄÄÄÄÄÄÄÄ220kÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĮÄ2M7ÄŁ
INDUCTIVE
BREAK TEST
Now test, & you should find the accuracy better & from DC-50Hz. And there is
no danger of electrocution if the neon indicator is used on Mains.
Why Don't U send an interesting bul?
73 De John G8MNY @ GB7CIP
Read previous mail | Read next mail
| |
